PO401 Defeated!!

[zipastro]

I had 3 Caddy horns for a while but they sounded goofy and I had 2 Caddy air compressors for a while but they burned up with moderate use.

-B-

OMG, I cant believe you would do something like this. The Toyota gods made a perfectly designed horn for your truck to begin with. Why didn’t you just trouble shoot and fix the very simple horn system your vehicle was designed with? It is a quite simple system as there are only 4 parts to work with, you have a switch, relay, wires and the horn. Work with it and maybe after 10-20 hours of labor and a horn wiring upgrade harness you could be beeping like the big guys

Come on....... this is ridiculous

Beowulf, Just take it for what its worth and move on. I am amazed when I read this post as to how you and other board members would attack someone for creating a viable work around to a -known- problematic weak spot on our fjz's.

 

[Beowulf]

Why didn’t you just trouble shoot and fix the very simple horn system your vehicle was designed with?

Good question Zipper. I didn't trouble shoot and fix the horn system because it wasn't broken.

-B-

 

[Rookie2]

Wrong, this is a very important thread. Many of our fjz's are pushing the 200K mark and are destined to soon have the po401\EGR temp out of range problems.

My recommendation was to close the thread, not delete it. Both sides of the issue have been presented so that anyone can make their own decision. There was no point in letting it degrade any further into a nonconstructive piss'n match.

Bear brought his ingenious idea

That's a bit of an overstatement... wouldn't you say?

High schoolers have been cutting faulty EGR valves (literally taking them out and bolting a plate over the hole) out of their ricers for years and plugging a resistor in place of the sensor to eliminate the CEL..., opting to spend their money on clear lense covers and bigger scoops rather than fix the problem.


Rookie2

 

[CJF]

I get this all the time in the shop. One thing that I keep finding is that the temp sensor will test out fine but does not work correctly causing the problem. Unless I see an obvious issue or a non testing out part the temp sensor is the first to be replaced.

For some reason I just took the time to read through this whole thread.

Seems like David's post got lost in the shuffle. Any thoughts on this?

Curtis

 

[zipastro]

Good question Zipper. I didn't trouble shoot and fix the horn system because it wasn't broken.

-B-

Beowupt, I am confused So why would anyone want to mess with a perfectly engineered Toyota honker? In my area the only people that mess with their horns are punk kids in ricers trying to scare little old ladies at cross walks.

This should not have ended up a pissin match but it did as most disagreements on this board tend to for some reason?

Never the less I feel its necessary to stay in this -match- because of how a couple -big- posters handled their objections and went on the offensive for bear. Know one ever said you had to agree but geez lets not be pricks about it.

If a mod wants to clean the -piss- out of this post and consolidate the info so we can move forward I am all for it.

 

[zipastro]

For some reason I just took the time to read through this whole thread.

Seems like David's post got lost in the shuffle. Any thoughts on this?

Curtis

Back on subject

That’s a good question, My EGR\CEL (egr temp out of range) probs started right around 100K. Back on the 80's cool site I found another guy with the egr probs who got it fixed by simply pulling the egr temp sensor and cleaning the carbon build up off.

It seemed perfectly logical as the carbon build up would insulate the sensor and give inaccurate data.

This worked great for about 10K miles but it came back and cleaning it did not fix the problem again. I have resistance tested it and all seems well. I have a hard time buying a rpl sensor for $100 that’s the size if my pinky and test out OK.

 

[Beowulf]

This worked great for about 10K miles but it came back and cleaning it did not fix the problem again. I have resistance tested it and all seems well. I have a hard time buying a rpl sensor for $100 that’s the size if my pinky and test out OK.

Zipastro,
There are 3 other components in the EGR system in addition to the temp sensor which appears from your post to be the only one you have tested.

There is the EGR modulator which can be replaced with no tools if it tests bad. Testing is easy; see your FSM.

There is the EGR valve which can be tested easily; replacing is a bit harder but still only a 1 job.

There is the VSV for EGR which is more difficult to test because you have to remove it to test it. Removal is a 1 job if you do it the easy way and don't remove the intake.

You also have some hoses connecting this stuff together which should be tested first (as suggested by Rick a LONG time ago.) Checking and/or cleaning the hoses is another 1 job.

Hope this helps.

-B-

 

[zipastro]

Beowulf,
Back about year ago I read this board from top to bottom and with the help of the manual I tested and cleaned all of the parts and found nothing out of spec.
The carbon build up on the EGR temp sensor was really the only thing that seemed suspect. The next step for me would be to start RPL ing parts that
-may- be defective.

One thing you need to remember is that the EGR system is only on a vehicle to reduce emissions. It does nothing to help with performance or mileage. The best analogy for the EGR system is "a brick in the toilet" Does it flush better with it inside? Nope but it does save a tiny bit of water.

My truck is 13 years old and has 150K miles on the clock, I am perfectly content
tricking it into thinking the EGR temp is within spec.

 

[Beowulf]

... with the help of the manual I tested and cleaned all of the parts and found nothing out of spec.

I'm sorry Zipper, I thought you said that you had not tested the VSV for EGR. I now understand that you have removed it, tested it, and it Ohm'd out OK. My mistake.

-B-

 

[Bear80]

Please re-read my FIRST POST -- This was in no way a permanent "fix" -- and OBVIOUSLY it "fixes" nothing as I STATED. My intention of this thread was to share with others a little "trick" I came up with.

The resistor only takes the place of the EGR temp sensor. In which case, it prevents the sensor from sending the computer an error of INSUFFICIENT EGR FLOW. The computer only looks for the temp sensor under certian conditions, NOT a consatant monitoring. If the problem is with the EGR, the computer only cares about it under the conditions it's monitoring.

With the resistor in place the computer will never get ANY readings of the EGR gas temps. So the computer will never see the problem and NEVER display an EGR temp error code. PERIOD. OBVIOUSL NOT A FIX TO THE PROBLEM

As I previously posted, just by keeping the computer clear of error codes it will operate in CLOSED loop which is far better than running in OPEN loop, even if the EGR problem is still there.

 

[Gumby]

I also beleive that this problem is as much software as hardware. I can't keep my light off. The components test fine. Based on DDs extensive experience, I think it might very well be the sensor, but then again it might be the VSV. I've cleaned all the parts with no result.

I like the resistor fix. It allows the system to function, which it will not do for me currently.

The EGR feedback system is a US federally mandated OBDII system. With OBDII the government required that certain systems proved they were working. Many manufacturers have had problems with this monitoring. Honda has a problems with the Accords EVAP system, for instance. In many, many cases the systems worked fine, but the monitoring systems fail. Downstream O2s are a fine example of this. I have little problem with letting the EGR system function as designed, but without the monitoring system working. Much like I would have little problem putting in a downstream O2 simulator if I couldn't feasably run a downstream O2.

I'm a die hard Toyota fan, but if a system doesn't work, I find a better one. I'd be happy to throw the EGR feedback sensor in the bushes with my stock horns, stock head unit, stock fuseable links, and stock running boards.

 

[Gumby]

I will also add that my constantly lit CEL has disguised other problems. I would like to have it back off again.

Currently, my EGR isn't working at all because of the P0401. If I can get it back to working by emulating the monitoring sensor, I would like that even though scan tool analysis has shown no spark knock or the attendant spark retard.

I also have no excessive NOX problems without my EGR, according to IDOT anyway.

 

[landtank]

I'll admit that if I was up against this problem and it was time for a sticker I'd probably defeat the sensor for the inspection. But I'm not sure that I could leave it that way, especially is there was some reason to sell the vehicle.

Not having or ever had this problem I can't say how formidable the diagnosis is but if your done, then your done.

This thread seems to have gone the same way that so many caster threads have, problem or not, if the owner isn't interested in pursuing the issue or recognizing one you're not going to make him over the internet.

Personally if I were to get this code tomorrow, the first thing I'd do is clean the system the best I could. Pull the rear exhaust manifold, egr pipe, egr valve and temp sensor and clean everything the best I could including the passage in the rear of the head.

If by chance you do revisit this problem and figure out what is not happening lets us know please.

And the "thinking like a girl" smart ass jab probably wasn't done at the best of times, sorry.

 

[zipastro]

I love this thread........
2 years 6 months 40K miles and no CEL

 

[Bear80]

Good to hear. However, since you brought it back up I should note that the resistor value is INCORRECT.

I've know this for some time but since so much flack was tossed about when I first started this thread I decided to wait and see if anyone trying this ever ran into problems.

I'll try and update this latter today but the short of it is that the computer is looking for a 1k ohm range NOT a 1 ohm. There is a discrepencey between the Toyota EWD and FSM -- turns out the EWD is WRONG and the FSM is correct, not what I would have thought.

 

[zipastro]

Interesting,
How do you think the wrong value affects the egr activation? Is the wrong value seen as the temp out of range to activate the egr system? I am perfectly satisfied if the computer is simply tricked into just not using the egr system.

Its been awhile but I think there are 4-5 things that have to fall into place for the sytem to activate.

Engine warm at x temp
Outside air temp at x
Exhaust gas at x temp
Vehicle speed between x and x
RPM's between x and x

Maybe the 1 ohm is accpeted as a possible temp reading by the computer but just out of range enough to not activate the system??????

 

[BrettinSanAntonio]

According to the FSM the ranges are:

122 (F) - 64K -97K Ohms
212 (F) - 11K - 16K Ohms
302 (F) - 2K - 4K Ohms

As I posted on a different thread, I am reading an open across the terminals on mine so it looks like mine is bad. CDan has one on the way. For kicks, I'll measure the resistance out of the box.

If you're going to attempt to "trick" your computer, I would guess that something in the middle range based off an exhaust gas temp of 212 degrees would be a good starting point. At 1 ohm of resistance, I think you've effectivly created a "short" as far as you ECM is concerned.

Good to hear. However, since you brought it back up I should note that the resistor value is INCORRECT.

I've know this for some time but since so much flack was tossed about when I first started this thread I decided to wait and see if anyone trying this ever ran into problems.

I'll try and update this latter today but the short of it is that the computer is looking for a 1k ohm range NOT a 1 ohm. There is a discrepencey between the Toyota EWD and FSM -- turns out the EWD is WRONG and the FSM is correct, not what I would have thought.

 

[zipastro]

So 1 ohm should be out of range???????????
still no CEL for me?
I will keep rolling with the 1 ohm, no brains no headaches

 

[BrettinSanAntonio]

So 1 ohm should be out of range???????????
still no CEL for me?
I will keep rolling with the 1 ohm, no brains no headaches

Hey, if it works for you, go with it.

The "range" starts around 1000 ohms and only goes up from there. If you want a funtioning EGR temp sensor, I've got a buddy that changed his out and later found his was good. He might still have it sitting in his garage taking up space.

 

[scoop]

Where can I get a 1k ohm resistor? I give up on fixing egr.