EGR Delete Questions... YES, I used search! (1 Viewer)

[Pin_Head]

Hi

1. It appears (if its legal in your area or if your rig is off-road-use only) that you can simply block off the EGR system with block-off plates and plugging/removal of vacuum control lines without affecting any engine functions. Correct?
2. It appears that you can simply short out the sensor line going to the EGR temp sensor on BOTH OBD1 and OBD2 vehicles and the Engine Controller will be none the wiser (It will simply see "high" temperature on the EGR all the time, and that apparently isn't a problem). Correct?

Are #1 and #2 above correct? If not, where am I wrong?

Thanks,

Muddy1

1. No reason to go to the trouble of removing it or a block off plate. As long as the valve is closed, just remove the vacuum line to the EGR and it will accomplish the same thing for a lot less work. It is easier to restore back to normal if you need to sell it or register it in another state.

2. No. Most people use a 5K to 10K resistor to "fool" the ECU. It is controversial whether it is a good idea to fool the system into thinking the EGR is working. Normally the ECU leans the mixture out during low load, high speed cruising when the EGR is open to lower combustion temperatures and increase fuel economy. With the EGR not functioning, the mixture will be lean and the ECU will need to rely of the O2 sensors to keep the AFR in the stoichiometric range by adding more fuel via adjustment of the long term fuel trim. The potential problems are that there may not be enough range in the trim table to fully compensate. Clearly, adding fuel is not good for your fuel economy. The EGR is also claimed to increase fuel economy by several % by reducing pumping losses at high speed partial throttle operation. The other potential problem is that the increased combustion chamber temperatures increase pinging, relying on the knock sensors to pull timing to prevent knock. This is widely discussed on the net, so Google it. It seems unwise to risk these problems for no gain and a loss of fuel economy.

 

[MisipLC]

bahamasair, what kind of filter did you install on the fuel tank vent line? Did you remove the TVV and install a plug? My engine is out to the surgeon and do not plan on reinstalling the EVAP when it returns. I'm lazy and a polluter. (1FE-FZ ODB II)

 

[mct75]

The debate about smog equipment is a heated one (pun intended) and for a long time I assumed it was required for a truck to run properly.

On my 22R truck, here's the vacuum lines as it shipped. 1988 22R (US49 "Federal" emissions)

Here's the vacuum lines for a 1988 Canadian 4x4 22R:

Same exact engine. Mr T. doesn't think you need EGR, PAIR pumps, or even a charcoal canister VSV for their 22R to function properly. Of course, the 22R is not a 3FE or 1FZ, but these two diagrams show just how non-essential all these emissions devices are to proper engine function.

A pic and the part number of the OEM resistor plug that came wih a brand new harness I bought for my 1994 last year.

82824-35020 Hope this helps.

This.... this is very interesting. The implications are that some 1fz motors didn't have factory EGR, correct?

EDIT- Actually, it sounds like non-California 1fz's don't care if EGR is working or not.
However, if the truck doesn't know if EGR is operational, then it shouldn't be messing with engine parameters such as leaning out the mixture when EGR is active.

 

[baldilocks]

The debate about smog equipment is a heated one (pun intended) and for a long time I assumed it was required for a truck to run properly.

On my 22R truck, here's the vacuum lines as it shipped. 1988 22R (US49 "Federal" emissions)

Here's the vacuum lines for a 1988 Canadian 4x4 22R:

Same exact engine. Mr T. doesn't think you need EGR, PAIR pumps, or even a charcoal canister VSV for their 22R to function properly. Of course, the 22R is not a 3FE or 1FZ, but these two diagrams show just how non-essential all these emissions devices are to proper engine function.



This.... this is very interesting. The implications are that some 1fz motors didn't have factory EGR, correct?

EDIT- Actually, it sounds like non-California 1fz's don't care if EGR is working or not.
However, if the truck doesn't know if EGR is operational, then it shouldn't be messing with engine parameters such as leaning out the mixture when EGR is active.

My 93 came out of Oregon. It has egr but no temp sensor. My 94 is a CA rig and I disabled the egr system by rearranging vacuum lines and disconnecting the temp sensor and I never got a CEL so maybe you are onto something.

 

[theish]

So just to add more fuel to the fire. Pun intended. When you block off the EGR system wouldn't the end result be a rich mixture? If the EGR is adding air that the mass air flow isnt seeing wouldnt the ECU compensate by adding fuel to get the mix right, if the egr isnt adding that air wouldnt the end result be a richer mixture?

[QUOTE="2. No. Most people use a 5K to 10K resistor to "fool" the ECU. It is controversial whether it is a good idea to fool the system into thinking the EGR is working. Normally the ECU leans the mixture out during low load, high speed cruising when the EGR is open to lower combustion temperatures and increase fuel economy. With the EGR not functioning, the mixture will be lean and the ECU will need to rely of the O2 sensors to keep the AFR in the stoichiometric range by adding more fuel via adjustment of the long term fuel trim. [/QUOTE]

I see why it would hurt fuel economy but why would it run lean with no EGR if it thinks its working? Also I thought lean mean higher temps, rich is lower temps from fuel cooling. That plus no egr re-circulation must result in lower temps no? Am I crazy?

Side note I have the 10k resistor on my 96 right now and it seems to be running fine.

 

[mct75]

I have a 92 California model with a disabled EGR (from the PO) and I do get code 71 on the CEL.

From what it sounds like, the logic is as follows:

EGR temp sensor has high resistance when cold, low resistance when hot. If the engine is up to temperature for so many minutes and the resistance is too high on that sensor == set CEL. If the resistance is low when this check is performed, no CEL.

Thus, shorting out the connector causes the ECU to say "EGR is fine because I detect heat in the pipe" and it goes on its merry way.

I have the sensor, and since the resistance is high (saying "low temperature in the pipe") I get the CEL.

I think it's a pretty binary test (Heat in pipe? Yes or no) so any resistance below the magic value should work. Considering Toyota does this from the factory (short the sensor) I think this is pretty much confirmed.

So just to add more fuel to the fire. Pun intended. When you block off the EGR system wouldn't the end result be a rich mixture? If the EGR is adding air that the mass air flow isnt seeing wouldnt the ECU compensate by adding fuel to get the mix right, if the egr isnt adding that air wouldnt the end result be a richer mixture?

[QUOTE="2. No. Most people use a 5K to 10K resistor to "fool" the ECU. It is controversial whether it is a good idea to fool the system into thinking the EGR is working. Normally the ECU leans the mixture out during low load, high speed cruising when the EGR is open to lower combustion temperatures and increase fuel economy. With the EGR not functioning, the mixture will be lean and the ECU will need to rely of the O2 sensors to keep the AFR in the stoichiometric range by adding more fuel via adjustment of the long term fuel trim.

I see why it would hurt fuel economy but why would it run lean with no EGR if it thinks its working? Also I thought lean mean higher temps, rich is lower temps from fuel cooling. That plus no egr re-circulation must result in lower temps no? Am I crazy?

Side note I have the 10k resistor on my 96 right now and it seems to be running fine.

EGR is tricky. Exhaust in your chambers means less propulsion because there's a smaller quantity of fresh air and fuel, so you have to press the throttle down farther to get the same charge of fuel/air. With no EGR, you should theoretically be able to use less throttle, however the engine now has to do extra work sucking air through a more restricted throttle opening. It's a dynamic situation with a lot of variables, manifold vacuum vs power output with and without EGR added in being the most complicated to think about for me.

However, my research above "proves" that Toyota doesn't think EGR is a required component for the 22R, and the 3FE/1FZ were in production at the same time. Thus, it is pretty safe to say that EGR isn't essential for those motors.

Can anyone here produce a vacuum diagram for a 1FZ-F? From what I can see online, those had no EGR.

EDIT- Boom, no EGR on 1FZ-F:

 

[Pin_Head]

The EGR gas has no oxygen and when it is added to the intake air, it displaces the oxygen in the incoming air making it less lean. With the EGR on, the ECU can lower the fuel delivery to maintain stoichiometry under high speed cruise conditions to improve fuel economy. The EGR also lowers the intake vacuum to reduce pumping losses to improve fuel economy.

When you block off the EGR and fool the ECU into thinking it is still working, I don't really know what happens. I imagine that the ECU will still try to reduce fuel, but will be opposed by the O2 sensors what will try to maintain stoichiometry via the LTFT. I don't know if the LTFT has the range to compensate fully or not. Combustion temperatures will increase, so you will be blowing more NOx.

I don't see any benefit to blocking it off or removing it and it has a down side in reducing fuel economy and increasing combustion temperatures. Performance is not enhanced because the EGR shuts off in high demand situations. EGRs have a historical bad reputation with respect to performance and reliability because when they first came out in the early 70s, they did decrease performance and they were unreliable. The situation is very different now with EFI engines.

 

[MisipLC]

Here are drawings for the 1FE EGR system.

 

[fj80rodngun]

I tried the egr disconnect, put a 10k res in plug looped vac connections and idle went very low and very rich exhaust. Reconnected everything and gonna roll with it. From now on if it ain't broke I ain't fixing it.

 

[Pin_Head]

I tried the egr disconnect, put a 10k res in plug looped vac connections and idle went very low and very rich exhaust. Reconnected everything and gonna roll with it. From now on if it ain't broke I ain't fixing it.

How do you know it is rich at idle? The only reliable way is a tail pipe sniffer test. Rich mixture produces carbon monoxide, which is colorless and odorless and if you notice the anoxia, you may be dead soon. If you smell gasoline, it is misfiring and at idle this is often due to a lean mixture.

 

[mct75]

I tried the egr disconnect, put a 10k res in plug looped vac connections and idle went very low and very rich exhaust. Reconnected everything and gonna roll with it. From now on if it ain't broke I ain't fixing it.

EGR isn't active at idle, so either yours was not operating correctly or you did not disable it correctly.

 

[fj80rodngun]

What is the proper way?

It went from normal smell smooth idle when connected to heavy benzene smell and low surging idle when disconnected.

 

[mct75]

I can't speak as to what the proper way is since the PO of mine smashed the valve in with a hammer.

But, I suspect that you may have introduced a vacuum leak or somehow your EGR was opening up at idle when it shouldn't have been.

 

[p0opstlnksal0t]

you had a vacuum leak it sounds like. the plumbing wasnt sealed up properly

 

[Payara Offroad]

View attachment 1277058 View attachment 1277061
A pic and the part number of the OEM resistor plug that came wih a brand new harness I bought for my 1994 last year.

82824-35020 Hope this helps.

Just an update. Just came from Toyota and this part is discontinued

 

[mct75]

Just an update. Just came from Toyota and this part is discontinued

Fortunately, it just shorts the wires together from what I can tell.

 

[Payara Offroad]

Just for general knowledge and to make it easier to anyone looking to make this.

I got the 4.7K ohm resistor, but they have in 1/4 watt or 1/2 watt. Which is the best way to go?

 

[mct75]

Just for general knowledge and to make it easier to anyone looking to make this.

I got the 4.7K ohm resistor, but they have in 1/4 watt or 1/2 watt. Which is the best way to go?

Assuming the ECU puts a full 12 volts across the terminals, 12 volts / 4700 ohms = 0.0025 amps. 0.0025 amps * 12 volts is 0.03 watts, so I would loosely assume a 0.25 watt resistor is plenty.



That said, if the OEM plug just shorts them together there's probably a massive input impedance and it won't matter anyway.

 

[kybishop]

I just finished the EGR delete on my 94 Land Cruiser.

Mine started running pretty bad, barely would idle and would die here and there if I didn't hold my foot on the gas. It was throwing a P071 code for the EGR system. Also I was getting a bit of chatter/rattling or knocking in the valves it sounded like. Like bad gas under a load...

I removed the EGR modulator and the EGR valve. Took the upper intake plenum off to clean it out. The tube in the plenum going from the EGR valve to the throttle body was clogged almost completely. Rest was pretty clean. I got new intake manifold gaskets and put it back together. Got some copper gasket sealer and sprayed the EGR valve gasket and put a block on that. Had a local machine shop make the block.

Cut off the end of the EGR valve at the tube and tapped a thread in it for a 3/8" plug. This way I didn't have to remove the tube, just capped it.

Turns out my wiring to the EGR temp sensor had the insulator sleeve on the wiring worn through to bare wires. This may have been part of my problem. I cut the plug off of the EGR temp sensor and just wired the two wires together, sealed it up and plugged it back in. I don't know what these wires to the sensor are made of but they are very stiff and would not twist together whatsoever. I tried to solder them together and could not get it to take. I put a crimp electrical connector on it and electric tape for now. I will put the liquid electric tape on it when I find mine or buy some new.

For the vacuum lines I just ran the one from the throttle body back into the throttle body as suggested in this thread. The only other one I had to deal with was the vacuum tube that ran from the EGR valve to the intake plenum. I just pulled the line and capped the plenum.

It now runs great! I was relieved once I got it together and started it back up. I also took this opportunity to change the fuel filter as I could see it better with the top plenum removed. It spit and sputtered for a bit then went into a nice idle. It improves idling and running the more I drive it. No chatter or rattle and idles wonderfully. Power is better. So far no code but I have only driven it about 30 miles.

Thanks for this thread and all the knowledge here. This helped me immensely in making decisions and working on this issue. It is what ultimately made me decide to do the EGR delete.

I love this forum.

 

[dcx13]

Not to re-open a can of worms, but would a dramatic increase in altitude have an effect resulting in Code 71 popping up repeatedly? I ask this only because my 94 FZJ has been throwing 71's almost every 150-175 miles since I started driving up into the Tetons & Rockies. Each time it comes up, I check the code and if it's nothing new, I just pull the 15A EFI and reset the ECU memory.

If this is somehow related to the elevation... I normally operate at sea level to 4000'... I'll just keep resetting. Otherwise, I guess the redneck bypass is in order until I get back home.