1fz-fe EGR disable ?

[tblume]

7shulz- your '93 may not have one, and may have the factory jumper in it's place like mine.

Also being OBD 1 the operating parameters are different on our trucks; I posted a thread with the details, but IIRC the EGR only operates on closed throttle and engine speed increasing (downhill?) I'll look for the thread to link here.

https://forum.ih8mud.com/80-series-tech/292362-burning-egr-question.html post 17 has the '93 FSM picture

 

[7schulz]

Thanks, I appreciate it.

 

[Ebag333]

If you disabled the EGR and left the EGR temperature sensor in place, I would guess that you were only getting the P0401 code, true? Since (as I'm sure you know) the ECU can only set that code when you go over 50 mph for at least 3-5 minutes and the EGR temps don't exceed 100F above ambient temperatures (measured from the MAF), if you were doing strictly in-town driving it could take weeks or months for that code to appear. Obviously I wasn't there, but I would guess that the ECU wasn't reading the EGR temperatures as correct, but that it had not yet managed to do a check on the system, as you had not exceed 50 mph for 3-5 minutes. If the previous check was good (before you disabled the EGR), is it possible that it was showing that result as it was the last known condition of the EGR system?

I was only getting the P0401 code. It'd be rather disturbing if I was getting P0402 with the EGR disabled!

I reset the ECU at least 3 times to see what happened. While my daily drive is fairly short (about 15 minutes) most of it is on the freeway (over 10). Usually the way it works out is by the time I hit the freeway the engine is warmed up. From what I've read in the FSM my daily drive is pretty much the exact way to test the EGR system.

I understand that if I was driving in stop and go traffic that it would not even test the EGR system, in that situation it would stay yellow (if I had reset the ECU) as it would never test it.

I'm not sure what you're saying here, as I'm getting confused when you are referring to "temps". Are we talking exhaust temps as read by the EGR temp sender, or coolant/engine temps as read by the coolant temp sender, or both?

Temps as read by the EGR temp sensor.

To rephrase, if the EGR system is flagged yet the ECU doesn't throw a CEL code, or even flags the EGR system as green (from a yellow status after being reset), isn't that an indication that the temps as read by the EGR temp sensor are in the correct range despite the EGR system not operating?

Combustion temps, yes. It sounded earlier like you were saying the EGR helped control the engine/coolant temps.

Sorry if there was confusion. I did reference the engine running cool (engine temps) merely to point out that the situation when the EGR system was running was a situation of little stress on the engine.

The EGR system doesn't control the engine/coolant temps. It might have a very slight effect on it as lowering/raising combustion temps will effect the engine temp, but it's small enough that it's not a significant factor.

Ale, bitter, stout, or lager?

My basic point is that it is well known that combustion temperature increases with increasingly lean air fuel mixture. This should not be confused with the engine heat that the cooling system has to deal with. If you run a really lean mixture for long enough it can lead to melting a piston, so the higher the combustion temperature, the more likely that this might happen. I didn't claim that it will always result in catastropic failure; just that it might increase the risk of it. Modern EFI engines in the US have been engineered to take advantage of the fact that the EGR cools the combustion temperature to run a leaner mixture than would otherwise burn at a safe temperature during light load cruise conditions to improve gas mileage and help meet CAFE standards. So what would happen if the engine did run lean without the EGR? We don't know and we don't know that it does run lean. It seems likely that the ECU will detect the excess O2 and enrich the mixture but this would result in worse fuel economy.

After reading the emissions section of the FSM, I don't know enough how the ECU responds a non functioning EGR to conclude that there is no potential problem. I feel reasonably confident that Toyota engineered it so as to protect the engine, but if you fool the ECU into thinking that the EGR is working rather than detecting the fault and setting the MIL, then maybe it might not work as Toyota intended. A lot of engineering went into this and it seems like an unnecessary risk to fool with it without knowing the details of how it works and how the ECU is programmed to respond under these conditions if you don't gain anything significant.

That's all great in theory, not so much in application.

The 1FZ tends to run rich rather than lean. The 1FZ has a fairly advanced knock/timing system in it to prevent a lean situation, which is why it's capable of running--and even running well--various types of fuel ranging from fuel contaminated with water and oil to premium that we find at the pumps here in the States. There are multiple people pushing 1k HP on 1FZ's with a surprisingly large amount of the engine left stock. While adding a blower isn't quite plug and play, the ECU is more than capable of handling it.

The point is that if the ECU can handle all of that, if it couldn't handle disabling the EGR system....well....that'd be a problem then, wouldn't it?

Add all that into the fact that many 1FZ's are running around without the EGR system from the factory, and I'm convinced that there are no major problems with disabling it.

I've been running without the EGR system for several thousand miles, and many people have been running without it for tens of thousands of miles. Zero pinging or any other indications that the engine is running too lean.

I challange you to show me a thread on here that describes engine failure of any sort that was attributed to the EGR system not functioning. Just one single example of it.

 

[96r50]

I was only getting the P0401 code. It'd be rather disturbing if I was getting P0402 with the EGR disabled!

I reset the ECU at least 3 times to see what happened. While my daily drive is fairly short (about 15 minutes) most of it is on the freeway (over 10). Usually the way it works out is by the time I hit the freeway the engine is warmed up. From what I've read in the FSM my daily drive is pretty much the exact way to test the EGR system.

I understand that if I was driving in stop and go traffic that it would not even test the EGR system, in that situation it would stay yellow (if I had reset the ECU) as it would never test it.

Hmm, that seems odd that it would flag green then if the EGR had been disabled. How did you disable it? Is it possible that your EGR valve is letting exhaust into the intake somehow (leak/not completely disabled)?

Temps as read by the EGR temp sensor.

To rephrase, if the EGR system is flagged yet the ECU doesn't throw a CEL code, or even flags the EGR system as green (from a yellow status after being reset), isn't that an indication that the temps as read by the EGR temp sensor are in the correct range despite the EGR system not operating?

It seems that way, but the question is why? I would think either the EGR temp sensor is reading funny or the EGR valve is leaking. What else could cause it?

Ale, bitter, stout, or lager?

Whatever is local or plentiful

Add all that into the fact that many 1FZ's are running around without the EGR system from the factory, and I'm convinced that there are no major problems with disabling it.

The only difference from that is the "from the factory" angle. Do we know if they are using different ECU programming? Maybe our EGR-programmed ECU has to compensate for the unexplained extra ratio of oxygen to fuel (due to the lack of inert exhaust gases normally introduced by the EGR) by changing timing or injector duration.


I dunno about you guys, but I'm enjoying this discussion since it's too damn cold to work on my truck!

 

[Pin_Head]

The point is that if the ECU can handle all of that, if it couldn't handle disabling the EGR system....well....that'd be a problem then, wouldn't it?

I challange you to show me a thread on here that describes engine failure of any sort that was attributed to the EGR system not functioning. Just one single example of it.

I don't doubt that the ECU can handle a non-functioning EGR. What I doubt is whether The ECU can handle it if you fool it into thinking that the EGR is actually working normally. If you are going to disable the EGR, I think it would be better not to fool the ECU and let it set the MIL and DTC. Live with the check engine light on.

Here is an example of a 1FZ with a melted piston. It isn't clear why it melted or whether it melted because of a non-functioning EGR, but it is a reasonable possibility because the function of the EGR is to lower the combustion temperature.

https://forum.ih8mud.com/hardcore-corner/341445-project-effjjay-eighty-2uz-powered.html#post5049601

 

[Ebag333]

Hmm, that seems odd that it would flag green then if the EGR had been disabled. How did you disable it? Is it possible that your EGR valve is letting exhaust into the intake somehow (leak/not completely disabled)?

It seems that way, but the question is why? I would think either the EGR temp sensor is reading funny or the EGR valve is leaking. What else could cause it?

Oh trust me, it's not leaking. The EGR modulator is completely blocked (and by completely, I do mean completely! ) which means no exhaust gas is getting through at all.

Whatever is local or plentiful

Can't fault you there.

The only difference from that is the "from the factory" angle. Do we know if they are using different ECU programming? Maybe our EGR-programmed ECU has to compensate for the unexplained extra ratio of oxygen to fuel (due to the lack of inert exhaust gases normally introduced by the EGR) by changing timing or injector duration.

I would agree except that I've seen nothing in the FSM to indicate such behaviour, nor have I seen anything in the way that the ECU handles the engine to indicate it (in real life).

There isn't any way for the ECU to tell if gasses are really getting dumped in there or not as they get dumped in post the MAF sensor, and there is no sensor to tell how much is being dumped in. All the ECU cares about is if the temp is in the correct range (which is extremely wide). It would make little sense to engineer the ECU to change the way the engine runs based on an effect that you have no way of measuring...especially since the change made would be to run the engine closer to the edge rather than running it in a safer mode.

Think about it this way...we know that the 1FZ tends to run on the rich side (and rather heavily). If Mr. T designed the 1FZ to run it rich, why would he then do a 180 and design it to run on the lean side (and have less margin for engine failure) based on a situation where he doesn't actually know how the engine is being effected?

Think about this too...I'd be willing to bet that if you took your average 80 (IE: not anal-retentively maintained) at least 30% of them would fail the EGR tests. But most of them probably aren't throwing a CEL. So the EGR is failed, yet no CEL is thrown. Mr. T is good at accounting for situations like that (think of the limp home mode that the ECU can go into), I'd have a hard time believing that a failed EGR (which you are replicating by disabling it) would be missed. IMHO it's more likely that it's simply a non-issue.

I dunno about you guys, but I'm enjoying this discussion since it's too damn cold to work on my truck!

Not too cold temp wise here, but up to 50 MPH gusts gives you a nice chill factor!

I don't doubt that the ECU can handle a non-functioning EGR. What I doubt is whether The ECU can handle it if you fool it into thinking that the EGR is actually working normally. If you are going to disable the EGR, I think it would be better not to fool the ECU and let it set the MIL and DTC. Live with the check engine light on.

Except for the small problem that much of the time the ECU thinks a non-functioning EGR is working normally.

Why else would the ECU flag a disabled EGR system green (after being reset) if it didn't think it was working properly?

By doing the resistor (for OBD-II) or the OEM solution (for OBD-I) you are simply eliminating the relatively small amount of time when the EGR temps fall below what they should be, and the ECU happens to catch it.

Here is an example of a 1FZ with a melted piston. It isn't clear why it melted or whether it melted because of a non-functioning EGR, but it is a reasonable possibility because the function of the EGR is to lower the combustion temperature.

https://forum.ih8mud.com/hardcore-corner/341445-project-effjjay-eighty-2uz-powered.html#post5049601

There's zero evidence that is due to a non-functioning EGR.

The guy said the rig was running rough for a while but continued to drive it to its untimly roadside demise pouring its lifeblood on the hwy. Consiting of mixed oil and coolant.

The EGR system can fail one of two ways:

1) Fail open (exhaust injected all the time).
2) Fail closed (exhaust never injected).

If the rig was running rough and it was due to to the EGR system, then that would mean that it was failure #1, because gas injected into the engine all the time could result in a rough idle. Type 2 failure would not result in the engine running rough.

So based your statement, and assuming it was an EGR failure, the piston meltdown must have been due to the combustion temp being too low!

That piston meltdown is as likely a result of a failed EGR system as my brakes siezing after a wheeling run being a result of me blocking off my EGR.

The fact is that you cannot point me to a single post where there was catastrophic engine failure due to the EGR system. It's simply not possible.

 

[7schulz]

I just took the vacuum lines and routed them back on each other to create two dead end loops. I looked high and low on my 93 and I don't think I have a temp sensor. I guess we will find out next time I take it for a longer drive. I did drive it around the neighborhood and no CEL.

 

[Ebag333]

I just took the vacuum lines and routed them back on each other to create two dead end loops. I looked high and low on my 93 and I don't think I have a temp sensor. I guess we will find out next time I take it for a longer drive. I did drive it around the neighborhood and no CEL.

Did you look at the EGR valve? Not the modulator (the one where you looped the vacuum lines) but the one that is attached to that.

 

[7schulz]

Yes I looked for a temp probe all over the place.
I looked for it like in this thread that Tblume sent me to and the other threads.
https://forum.ih8mud.com/80-series-tech/292362-burning-egr-question.html
I don't know.

 

[Ebag333]

Here's a pic of it. You can see the bolt head where Tblumes was removed. It is just up and to the right of the wiring harness plug (which is for the temp sensor). Note that the EGR modulator has been removed.

And the FSM pic.

 

[7schulz]

Is it only me or are the pics you just posed not showing up all the way?

 

[Ebag333]

Shows fine for me.

 

[Pin_Head]

The fact is that you cannot point me to a single post where there was catastrophic engine failure due to the EGR system. It's simply not possible.

Try Googling:

"Melted piston + EGR" or "disable EGR problems"

The results might change your opinion.

 

[Ebag333]

Try Googling:

"Melted piston + EGR" or "disable EGR problems"

The results might change your opinion.

Nope, didn't change my opinion. Either of the 1FZ able to handle disabling the EGR, or how poorly built and designed certain manufacturers engines are.

Let me rephrase slightly....

The fact is that you cannot point me to a single post for a 1FZ where there was catastrophic engine failure due to the EGR system. It's simply not possible.

 

[alaskacruiser]

Think about it this way...we know that the 1FZ tends to run on the rich side (and rather heavily). If Mr. T designed the 1FZ to run it rich, why would he then do a 180 and design it to run on the lean side (and have less margin for engine failure) based on a situation where he doesn't actually know how the engine is being effected?

He knows the EGR temperature is within one of 3 ranges. Though the ranges are wide, nobody knows the margins involved with leaning the fuel mixture under those ranges (except the Toyota engineers).

Except for the small problem that much of the time the ECU thinks a non-functioning EGR is working normally. Why else would the ECU flag a disabled EGR system green (after being reset) if it didn't think it was working properly?
By doing the resistor (for OBD-II) or the OEM solution (for OBD-I) you are simply eliminating the relatively small amount of time when the EGR temps fall below what they should be, and the ECU happens to catch it.

It flags it as green because the EGR temperature sensor reading happens to fall into the proper range, whether it is bypassed with a resistor, or not working, or whether the EGR is blocked off. However, this is one sample point out of hundreds of combinations of environmental/driving conditions. I don't think the fact that the ECU flags a disabled system as green is significant, as it does nothing to disprove other possibly harmful effects.

Add all that into the fact that many 1FZ's are running around without the EGR system from the factory, and I'm convinced that there are no major problems with disabling it.

I've been running without the EGR system for several thousand miles, and many people have been running without it for tens of thousands of miles. Zero pinging or any other indications that the engine is running too lean.

I think the point Pinhead and 96r50 are trying to make is that those 80s that came from the factory without EGR, or with it easily jumpered/disabled are probably fine. However, we all know the ECUs changed between the 93-94 models and the 95-97 models, so it may well be that there are conditions when the 95-97 ECU MAY lean out the fuel mixture IF it is being fooled by a resistor and blocked EGR. Nobody has yet proven if this happens, and if so what the resulting combustion temperature difference is. And no amount of hand-waving about 1000hp cruisers, or 3-5 sample points of mudders running a few k without any noticeable problems changes that. Only cold, hard fuel mixture data on 95-97 US models with this modification will tell us something.

The fact is that you cannot point me to a single post where there was catastrophic engine failure due to the EGR system. It's simply not possible.

The failure of a melted piston or whatever the failure mode may be may not be sudden and catastrophic in nature. It could simply reduce the lifetime of the engine before a rebuild is required- or perhaps it is a slow process and you may see a melted piston at 300K when you wouldn't have had one otherwise.

In the case of modifying a stock vehicle, the onus is not on one to show that the modification has caused problems. The onus is to show that the modification will not reduce the lifetime of the vehicle. Many people believe in running a K&N filter on their vehicles and can say the same thing "show me one instance of a failure". But it has been shown empirically that the K&N filter does not filter as well as the stock Toyota air filter (will have to find link). This may not cause a problem in 100k mi., but who knows if it may keep you from seeing 300k without a rebuild? Perhaps we'll start seeing the K&N guys rebuilding earlier, but either way we likely won't see catastrophic failures, and your "show me one case" logic doesn't work there, either.

Can a Scanguage help determine what's happening with the fuel mixture? I'd like to find a way to get some real data on this. Anything else is just a guess.

 

[Ebag333]

He knows the EGR temperature is within one of 3 ranges. Though the ranges are wide, nobody knows the margins involved with leaning the fuel mixture under those ranges (except the Toyota engineers).

It flags it as green because the EGR temperature sensor reading happens to fall into the proper range, whether it is bypassed with a resistor, or not working, or whether the EGR is blocked off. However, this is one sample point out of hundreds of combinations of environmental/driving conditions. I don't think the fact that the ECU flags a disabled system as green is significant, as it does nothing to disprove other possibly harmful effects.

Think about what you just said.

System 100% failed closed (no exhaust flow). Flagged as green by the ECU. ECU leans out mixutre because it see's the EGR as functioning. Boom, engine failure.

This is not an abnormal scenario (except the last part). Many cruisers are driving around with their EGR system plugged up and no CEL's.

Please explain how having the EGR system not working and the ECU thinking it is is any different than the EGR system not working (disabled) and the ECU thinking it is (resistor).

Why would Mr. T build an engine that is designed to fail under normal use?

And no amount of hand-waving about 1000hp cruisers, or 3-5 sample points of mudders running a few k without any noticeable problems changes that. Only cold, hard fuel mixture data on 95-97 US models with this modification will tell us something.

Even taking 1k HP cruisers out of it, you're honestly trying to suggest that I can slap a blower on my truck and run it just as reliably but disable my EGR system and it'll kersplode?

A blower will have a bigger effect on the EGR system. As for people running with disabled EGR systems, Bear80 has been running his for 5 years. That's plenty long enough for me.

In the case of modifying a stock vehicle, the onus is not on one to show that the modification has caused problems. The onus is to show that the modification will not reduce the lifetime of the vehicle.

Except I'm not claiming it won't reduce the lifetime of the vehicle.

I can claim the following:

1) You won't toast your main engine wiring harness.
2) You won't be dumping crap back down your engine. (You can decide for yourself what dumping carbon into the combustion chamber will do for the lifetime of the vehicle, seems to me that's probably as bad or worse than a K&N filter).

If I were claiming that disabling the EGR system will extend the life of the vehicle, I would. So there's no onus there on me.

Heck, most of the mods you see here are not about extending (or even maintaining) the lifetime of the vehicle. You think that a heavily wheel built 80 that's been driving through Rubicon multiple times will last as long as a pristinely maintained mall cruiser? If the onus was to prove that mods wouldn't reduce the lifetime of the vehicle Slee, MAF, and many others would be in some serious trouble.

Besides, I'm not the one claiming that it will destroy the engine. All I'm asking Pin Head to do is backup his claim that disabling the EGR system on a 1FZ will cause catastrophic engine failure.....which he can't. So the onus is on him to prove his ludicrous claim.

Many people believe in running a K&N filter on their vehicles and can say the same thing "show me one instance of a failure". But it has been shown empirically that the K&N filter does not filter as well as the stock Toyota air filter (will have to find link). This may not cause a problem in 100k mi., but who knows if it may keep you from seeing 300k without a rebuild? Perhaps we'll start seeing the K&N guys rebuilding earlier, but either way we likely won't see catastrophic failures, and your "show me one case" logic doesn't work there, either.

Difference is that as a K&N naysayer I can point to tests that show that a K&N doesn't filter much (if any) better than our OEM filter does, filters more poorly, and is a smaller surface area.

So if I'm going to claim that a K&N is bad for our rigs, the onus is on me to backup my claim. Which I can.

If you want to continue to claim that disabling the EGR system is bad, then the onus is on you to prove it.

Can a Scanguage help determine what's happening with the fuel mixture? I'd like to find a way to get some real data on this. Anything else is just a guess.

IIRC the scangauge does have some visibility into fuel usage. Not sure how much.

 

[alaskacruiser]

Think about what you just said.

System 100% failed closed (no exhaust flow). Flagged as green by the ECU. ECU leans out mixutre because it see's the EGR as functioning. Boom, engine failure.

Straw man argument, anyone? I don't think anyone is saying "boom, engine failure", not even Pinhead, as he's clearly stated in a previous post. In fact, he put it best so I'll just paste it in right here:

My basic point is that it is well known that combustion temperature increases with increasingly lean air fuel mixture.[...] If you run a really lean mixture for long enough it can lead to melting a piston, so the higher the combustion temperature, the more likely that this might happen. I didn't claim that it will always result in catastropic failure; just that it might increase the risk of it. Modern EFI engines in the US have been engineered to take advantage of the fact that the EGR cools the combustion temperature to run a leaner mixture than would otherwise burn at a safe temperature during light load cruise conditions to improve gas mileage and help meet CAFE standards. So what would happen if the engine did run lean without the EGR? We don't know and we don't know that it does run lean.

And I'll add to that that this is a specific concern on the 95-97 models because there may have been changes to the ECUs in these models to lean out the fuel mixture. We know the ECUs are different in the 95-97 models. We even know the EGR trip logic is different. Is it such a leap to consider the possibility that the ECU's programming may have been modified to lean the fuel mixture w/rt EGR? I don't think so. However, on the 93-94 models, your conclusion seems reasonable, esp. with the factory disable option.

Please explain how having the EGR system not working and the ECU thinking it is is any different than the EGR system not working (disabled) and the ECU thinking it is (resistor).

Why would Mr. T build an engine that is designed to fail under normal use?

Now, the fact that your truck produced a P0401 once a week or so while the EGR was blocked is interesting. It is also a single data point. Can you tell us exactly how you blocked the EGR during this test? I was getting a code about 2-3x a week when I initially had a P0401 and before I made any modifications, but I was also driving a lot more then, and mostly freeway. How do you explain that? Especially if you consider that it is 2 trip detection logic, it was really detecting it 2x as much as was indicated by the CELs you and I got. The CELs we were getting may have put the ECU into a failsafe mode as far as leaning the fuel mixture, hence preventing potential damage, contrary to your "designed to fail" statement. Maybe it didn't trip the CEL immediately, but again, you are going off the straw man of "engine go boom" the minute the fuel mixture is leaned. I am talking about long-term, cumulative damage caused by running lean that could show up tens of thousands of miles, maybe hundreds of thousand of miles, or years later. Yet you repeatedly pick at low hanging fruit instead of addressing this possibility.

This is not an abnormal scenario (except the last part). Many cruisers are driving around with their EGR system plugged up and no CEL's.

This may apply to the 93-94 cruisers, but I do not think it applies to a majority of 95-97 cruisers. Can you show me some examples?

Even taking 1k HP cruisers out of it, you're honestly trying to suggest that I can slap a blower on my truck and run it just as reliably but disable my EGR system and it'll kersplode?

That deserves a by itself since you again bring up the "engine go boom" straw man without addressing the potential long term effects. As for adding a blower to the truck, I would guess you would be making your engine less reliable over the long term (more points of failure) and possibly reducing its lifetime, but with the benefit being performance. With the EGR mod, you have no performance benefit, and any advantages related to HG failure or a cleaner intake are meaningless if engine lifetime is reduced.

Except I'm not claiming it won't reduce the lifetime of the vehicle.

I can claim the following:

1) You won't toast your main engine wiring harness.
2) You won't be dumping crap back down your engine. (You can decide for yourself what dumping carbon into the combustion chamber will do for the lifetime of the vehicle, seems to me that's probably as bad or worse than a K&N filter).

If I were claiming that disabling the EGR system will extend the life of the vehicle, I would. So there's no onus there on me.

C'mon Ebag333- in your previous thread where you listed the potential benefits of this mod, you brought up the possibility of preventing HG failure, the wiring harness, and of course the carbon. And you don't think all of that implies something about whether you think it's good for your engine or bad for your engine, and hence whether your engine will live a longer or shorter life? The implication is obvious, and your not admitting it now is only a technicality for the sake of argument. For what good are ANY of those advantages you listed if you are potentially reducing the lifetime of your engine? What good is keeping your original HG if your engine needs a rebuild at 200K, while unmodified vehicles may be getting 300K, for example? So engine lifetime is an integral part of performing this mod. Because, unlike a turbo, with this EGR mod you aren't gaining performance, and nobody is doing this just to keep a CEL off, or just to put off changing out parts, I would guess most would do it because they believe it is good for their motor- possibly preventing headgasket failure, protecting the wiring harness, and reducing sludge in the intake- all things people might want if they want their engine to last as long as possible. See the link? And you're telling me someone doing the mod for all the reasons you listed shouldn't also be concerned about its possible effect on engine lifetime? Perhaps we should do a poll. Nobody's holding you liable for anything here, but to write out a list of advantages of the mod, all good for the longevity of the motor, and then claim you never specifically said you think it will extend engine lifetime when a possible concern suddenly comes up makes it sound like you're protecting a product. How about we look at this as a mod without getting caught up in semantics like that? Everyone sees right through that stuff, anyway.

Difference is that as a K&N naysayer I can point to tests that show that a K&N doesn't filter much (if any) better than our OEM filter does, filters more poorly, and is a smaller surface area.

So if I'm going to claim that a K&N is bad for our rigs, the onus is on me to backup my claim. Which I can.

If you want to continue to claim that disabling the EGR system is bad, then the onus is on you to prove it.

Someone who's thinking of doing this mod may ask "Hey Ebag333- I have a 95-97 cruiser. I'd like to do this EGR mod, but I don't know if the ECU in these vehicles will lean out the fuel mixture if I blockoff the EGR and bypass the EGR temp sensor with a resistor. We all know running long term in a lean condition, over time, can cause engine damage and effectively reduce the lifetime of your engine, so I want to make sure this is safe. Can you tell me if the ECU is leaning out the fuel mixture when it is faked like this?"

My answer, Pin-head's answer, and your answer are effectively the same: I don't have the data to answer that question. Your answer might also include your one sample point of your CEL coming on only once a week when you disabled your EGR, that you can't hear any pinging, Bear80's years using this mod (have you talked with him about how long he's been running it, BTW?), blown 80s, 93-94 models which had a factory disable, that the lack of short-term catastrophic failure implies it's safe long-term, and your guess as to the margins involved in leaning the fuel mixture under temperature ranges which (based on...no calculations?) you consider "too wide" to do so, but none of that proves anything, and in the end, you are really saying you don't know.

Heck, most of the mods you see here are not about extending (or even maintaining) the lifetime of the vehicle. You think that a heavily wheel built 80 that's been driving through Rubicon multiple times will last as long as a pristinely maintained mall cruiser? If the onus was to prove that mods wouldn't reduce the lifetime of the vehicle Slee, MAF, and many others would be in some serious trouble.

Trail damage and engine damage are very different creatures. I think you will agree that many, if not most, who wheel their rigs are anal about maintenance, hence yes they do care about reliability and engine lifetime. Your argument makes no sense because Slee's and others' mods are to protect your vehicle offroad when you choose to take it offroad- it is your choice to take your vehicle offroad, and not their mods, that may reduce vehicle lifetime, if anything, and we're talking trail damage and not engine damage. On the other hand, with the EGR mod, it is the mod itself that may cause the damage, and it is engine damage, not trail damage. The benefit you get from Slee's mods is vehicle protection offroad. The benefit you get from the EGR mod is potential reduction in HG failure, less sludge in intake, and a possible long-term lean-running condition that may reduce the lifetime of your engine, which would make the other benefits totally pointless. The comparison is laughable.

Besides, I'm not the one claiming that it will destroy the engine. All I'm asking Pin Head to do is backup his claim that disabling the EGR system on a 1FZ will cause catastrophic engine failure.....which he can't. So the onus is on him to prove his ludicrous claim.

Ebag333- no need to be so defensive about this mod, especially since Bear80 did it before any of us. Pin_head's claim is not ludicrous since neither of you (nor I) have the data to prove or disprove it. And again, the concern isn't with "lean...kaboom", but more with the potential for long term damage caused by running lean over an extended period (years and 10s or 100s of k mi.) Moreover, go ahead and do the google search Pin-head suggested and you'll find a lot of problems potentially caused by EGR-delete and running lean. You say this doesn't apply to the 80 because EGR was an afterthought, and you may be right about the 93-94 models, but you cannot say that about US 95-97 models ECU without data to back it up. Nobody has the data to show whether the ECU leaning out the mixture w/ EGR modded is happening, but burying your head in the sand and claiming this risk does not exist unless Pin_head or I "prove it" because we happened to "call you out" on it isn't helping anybody. The fact is, we aren't "calling you out" on anything- this isn't personal, this isn't really even your mod to get personal about since, as far as we know, Bear80 did it first. We are trying to discuss the potential pros and cons of a mod in a thorough manner, which means exploring all the possible effects and impacts- positive and negative. The fact remains that this mod may cause a '95-97 truck to run lean over time, which would be a potential risk, and it should be considered as such until proven otherwise. Instead of pointing the finger at Pin_head or myself, I hope we can work together with the forum to find a way to obtain data on this.

IIRC the scangauge does have some visibility into fuel usage. Not sure how much.

Will have to look into this...

 

[yoopercharged]

Well written alaska. We need some Toyota Engineers on MUD. Lots of good theory here, but no real data.

 

[Ebag333]

Straw man argument, anyone?

And I'll add to that that this is a specific concern on the 95-97 models because there may have been changes to the ECUs in these models to lean out the fuel mixture. We know the ECUs are different in the 95-97 models. We even know the EGR trip logic is different. Is it such a leap to consider the possibility that the ECU's programming may have been modified to lean the fuel mixture w/rt EGR? I don't think so. However, on the 93-94 models, your conclusion seems reasonable, esp. with the factory disable option.

If you're going to call someone out on a straw man arguement, it's probably a good idea to not turn around and make one the next paragraph.

The ECU may lean out the mixture. The programming may be different.

You have zero evidence of a lean condition being caused by the EGR system being disabled. Yet you continue to through out that it may happen.

Running 15w-40 oil could cause damage to your engine. Some other engines which are nothing like the 1FZ are damaged when you run 15w-40 as it's too heavy for them, so you shouldn't run 15w-40 oil.

That's about how relevant Pin Head's (and yours) claims are. Some engines lean out the fuel mixture when the EGR system is active, but there's zero evidence that that 1FZ's ECU does so.

The CELs we were getting may have put the ECU into a failsafe mode as far as leaning the fuel mixture, hence preventing potential damage, contrary to your "designed to fail" statement.

This may apply to the 93-94 cruisers, but I do not think it applies to a majority of 95-97 cruisers. Can you show me some examples?

Both these statements show a basic misunderstanding of the way the EGR system operates and is setup.

First of all, the only visibility the ECU has into the EGR system is that single temp sensor. Which means when the EGR system is flagged greeen, that temp sensor is in the correct range.

So it makes no sense for the engine to be in a failsafe mode right after it flags the EGR system as green. That would be a level of visibility into the EGR system that simply doesn't exist.

Secondly, the "designed to fail" statement means that the EGR system will plug up. That's a simple fact. With components of that sort it's the nature of the beast. The O2 sensors will die eventually because in order to measure the exhaust they have to be in it (and exposed to carbon, unburnt fuel, etc). The EGR system pipes exhaust back into the engine, so it will get plugged up over time.

My point (which you've either completely missed or ignored) is that the EGR system will disable itself over time. It will get blocked and no longer push as much (or any) exhaust into the plenum.

So explain to me why the EGR system being plugged up over time is okay, but mimicing this by disabling the EGR modulator is bad?

If disabling the EGR modulator is bad, then any non-functioning EGR system is equally bad. Capiche?

The problem with that idea goes back to point one, the engine's visibility into the system is only the temp sensor. Which anyone with a plugged (or disabled) EGR system can tell you the ECU thinks is fine quite often.

Which goes back to the "designed to fail" statement. EGR system is blocked (disabled or over time), ECU think's it's fine, leans out the engine.....and you have a problem. Whether that's "engine goes boom" or just knocking a few thousand miles off the life of the engine, that's up to you.

I have a hard time believing that Mr. T would design the 1FZ in a way that it's going to fail in such a manner.


As for your "show me some examples," again you have a misunderstanding of the way the EGR system works.

The EGR system between OBD-I and OBD-II vehicles is nearly identicle. The only difference is the location of the temp sensor, which is closer to the combustion chamber in the OBD-II vehicles. The EGR pipe, modulator, valve, and vacuum lines are the same. Which means that the EGR system can (and will) fail in the same manner as the OBD-I trucks.

Go search for P0401 and you'll find plenty of examples of OBD-II trucks that have this code from the EGR being blocked.

But perhaps you can explain why two nearly identicle systems would behave entirely differently?

With the EGR mod, you have no performance benefit, and any advantages related to HG failure or a cleaner intake are meaningless if engine lifetime is reduced.

I'd say that dumping less crap into the engine will increase the engine lifetime. I'd say that not blowing a headgasket is a performance benefit (ever seen how well an engine runs with a blown HG?). I'd even say that not melting your main engine wiring harness might be important for performance (and possible the life of all sorts of stuff, including the ECU).

Someone who's thinking of doing this mod may ask "Hey Ebag333- I have a 95-97 cruiser. I'd like to do this EGR mod, but I don't know if the ECU in these vehicles will lean out the fuel mixture if I blockoff the EGR and bypass the EGR temp sensor with a resistor. We all know running long term in a lean condition, over time, can cause engine damage and effectively reduce the lifetime of your engine, so I want to make sure this is safe. Can you tell me if the ECU is leaning out the fuel mixture when it is faked like this?"

My answer would be:

1) There is zero evidence of a lean condition. There is zero evidence of this causing problems, despite some people running it for 5+ years.

2) Do your own research and make your own decision on whether you are comfortable with the mod or not.

My answer, Pin-head's answer, and your answer are effectively the same: I don't have the data to answer that question. Your answer might also include your one sample point of your CEL coming on only once a week when you disabled your EGR, that you can't hear any pinging, Bear80's years using this mod (have you talked with him about how long he's been running it, BTW?), blown 80s, 93-94 models which had a factory disable, that the lack of short-term catastrophic failure implies it's safe long-term, and your guess as to the margins involved in leaning the fuel mixture under temperature ranges which (based on...no calculations?) you consider "too wide" to do so, but none of that proves anything, and in the end, you are really saying you don't know.

That's all nice in theory but the problem is that you cannot prove a negative.

"Prove that this won't harm my engine."

Sorry, I can't prove that any more than I could prove that the 7 pin mod won't damage something else. After all, what if there is some hidden logic in the TCU that is based off that wire and subtly changes the operation of the engine or tranny that would shave life off the motor or tranny? There could be and there's no way to tell until you've ran hundreds of rigs with that configuration for 300k+ miles. And even then someone could point out "Well you just haven't waiting long enough."

I can provide evidence that it does no harm. I can point to the fact that by disabling the EGR system you're doing nothing more than what will naturally happen over time (if you don't replace components). I can point to the fact that I've seen zero evidence of a lean (or fuel rich) situation. I can point to the fact that quite a few people are running with their EGR disabled for both OBD-I and OBD-II trucks for years without an issue.

The fact remains that this mod may cause a '95-97 truck to run lean over time, which would be a potential risk, and it should be considered as such until proven otherwise. Instead of pointing the finger at Pin_head or myself, I hope we can work together with the forum to find a way to obtain data on this.

The WAG is that this may cause a '95-'97 truck to run lean over time. It's not a "fact" until it's been proven.

What I am pointing at you is your continued blasting me for "straw man" arguements then stating the lean condition as if it were a fact, or acting as if the onus is on me to prove your statement.

It'd be like if I asked you to prove that you were not using diesel in your 80. Think about how you could prove that to me. No matter what evidence you gave, it's impossible to prove. Photo? Photoshopped! Chemical analysis of the fuel in the tank? Faked, or you just put it in there for the test. Show it to me in person? Staged.

It's not much different from the conspiracy theorists. Why do you think people still believe the moon landing was staged?



To make it simple.....show me any evidence of a lean condition. Not "well Toyota MIGHT have changed the way the ECU worked" but actual fact. Show me something from the FSM. From the technical documents. Show me spark plugs that are toasted after running in a rig with a disabled EGR system (which, BTW, mine are absolutely fine).

You show me one single shred of evidence for this lean condition and I'll eat my hat (figuratively, of course. I like my hat.). Until then your statement that there may be a lean condition holds about as much water as the statement that there may be a Loch Ness monster.

 

[alaskacruiser]

Ebag333- I think my last post speaks for itself, and your response does, as well. You completely missed my point (and Pin_head's before that) about why the EGR plugging itself up is ok, but not with the mod. You also missed a major point about this not being personal as in "he has to prove this and I have to prove that", but rather exploring the pros and cons of a mod thoroughly and as a group. In fact, I'm beginning to think you missed my post altogether, as it addresses almost all the questions you brought up. I'll just kindly ask that you to reread my post so I don't keep retyping the same things. No, we don't know that the ECU leans the fuel mixture, and you don't know that it doesn't. That's the point- figuring it out, not some pissing contest you seem to want to initiate for some unknown reason.

Proving this negative should be possible, and myself and several others think it is important to do as a precautionary measure- it would mean either finding the appropriate documentation, and/or monitoring the fuel mixture (via OBD2?) with and without EGR mod under similar conditions. Hopefully others will be more helpful than yourself in looking into the possibility of a lean condition (nobody is stating this as a fact, but as a possibility to look into as a precaution, but there was a helluva lot more of my post you ignored, as well, so I'll stop here).

I'd appreciate your input on figuring this out, as you've been a valuable resource on this in the past. Your sudden change in tone when it comes to exploring the possibility of a potential problem of this mod is truly curious- I don't understand why this is so personal for you when it is just a mod on a truck, and it's Bear80's mod at that, but anyway I hope you can help move this forward instead of defending some imaginary turf.