PO401 Defeated!!

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Ahhhh, now I get it. Tanks tank. That brings back fond memories of Miss Rhodemaker. She handled me ever so gently during my formative years and I have her to thank for my tenacity and appreciation for the scientific method.

-B-
 
Beowulf said:
Or at 300% and 50 degrees higher than design spec?

-B-
Could be but who knows, anything is possible but it might even be well within specs?

Now if we had half as many self taught EGR engineers as we do oversized tire,suspension,bumper,roof rack,induction and electrical experts we just might know the answer. :confused:

Get the point here or do i need to get that third grade teacher everybody likes so much to explain things out?
 
The issue with the EGR codes is that while the system indicates a problem it's not specific enough to pinpoint the failure. So it rests on the mechanic to troubleshoot the system to identify the problem. The system is rather complex but not all that difficult to understand.

The FSM has very good instructions on how to test the individual components to deduce where the problem is. However most just want a quick cure all answer so they can "make it go away".

If I was to attack this problem I'd first start by cleaning all the ports in the system. This would entail removing the rear exhaust manifold, upper intake plenum and the EGR tube from the head to the valve. Clean all these out along with the temp sensor and the passage in the head and replace with new gaskets. Next I'd inspect the modulator for contamination and replace if needed. Once back together I'd start to evaluate the operation of the different items on the control side of the system.

As you can see this is a long process and there is nothing saying that an iexperienced machanic will even see the problem if it presented itself during this proceedure, let alone a back yard one.

Guys have fixed there egr systems but it's been mostly a hunt and pick sort of approach with sonme cleaning and some part replacement.
 
Junk said:
2 weeks <> crap. Give it time. ::
11 months 20,000 miles and counting...........:flipoff2: :flipoff2:


No CEL
No change in power
No change in mileage
No burned up engine from over temp exhaust
No x-tra money in Mr Toyota's hands
No more time wasted trying to figure out a weak trouble prone system


Only problem I have noticed is that my driver side visor no longer holds its self up, coincidence???????????
 
zipastro said:
No x-tra money in Mr Toyota's hands
No more time wasted trying to figure out a weak trouble prone system

Time for Dan to get out the knitting needles. What year & color is/was your truck?

-B-
 
I was just going to pull the one out of the radiator that is plugging the hole..;)
 
.47 ohm, 5 watts, eh? Might have to stumble across one of those. Only as a temporary fix, of course! :D :cheers:
 
Bear80 said:
LOL!!!

Great, I replaced my modulator to the updated blue top and still my cel kicks on every now and then. I just plug the resistor in and no worries. I think the temp sensor is next in line to be changed. But so far 1-1/2 years and the resistor keeps the cel off. :cheers:

Did you ever change the VSV for EGR? The modulator is pretty cheap and so easy to change that it's normally the first on everybodies list, but it rarely seems to fix the problem. The VSV seems to be the culprit more times than not (as in my case... 1 1/2 years and no CEL!!)

Seems like if you're smart enough to rig-a-ma-gig the system and trick it into no CEL, you're smart enough to diagnose and pinpoint the problem.

:beer:
Rookie2
 
Bear80 said:
well I don't see how the vsv could go bad.

Trust us Bear, the VSV for EGR can go bad. I have one on the work bench and will be happy to meter it and take pics if you are unconvinced. My guess is that carbon can get inside and short out something. I have considered opening it up and see how it works (or doesn't work) but my motivation is fairly low.

-B-
 
Bear80 said:
So if the vsv, modulator and egr can hold up on the mini, why would the one on my 80 fail?

Sorry, Bear, but I agree with Rick on this. How you can leap to this conclusion when comparing 2 very different vehicles with very different engines, EGR equipment, etc. is beyond me. Your solution is one step away from removing the bulb from the check engine light. You may not see any immediate problems, or even a year from now, but have you considered the possibility that you are reducing the longevity of your engine this way?

You talk about posts in which people have tried throwing parts at the problem to no end or just to have the problem return, but this is not the norm. If you follow the threads, you'll find many who systematically approahced the problem, replaced the appropriate parts, and have not had the problem return.
 
Bear80 said:
...I have 20 years and 335k miles on my mini truck and it has never had a egr problem...
The entire function of the EGR temp sensor is to enable the ECU to ascertain if the EGR is functioning in accordance to the ECU's commands.

Your 20 year old mini truck ECU does not have such feedback from the EGR in order to determine whether it is functioning according to ECU commands.
 
Bear80 said:
well I don't see how the vsv could go bad. The only thing that would cause a vsv failure would be carbon, which my system had none of. Plus I have 20 years and 335k miles on my mini truck and it has never had a egr problem. So if the vsv, modulator and egr can hold up on the mini, why would the one on my 80 fail?

The VSV can and does go bad. Mine did. Replacing it fixed the CEL problem.
 
Bear80 said:
I was only making a simple compairison with the truck. I really could give 2 s***s about all the posts telling me to find the "problem". And it seems everyone here thinks they have some great 2 cents to add. If it bothers you so much why don't one of you guys come show me how to work on my trucks since I'm such a novice.

It's a poor comparison for two systems that are built to meet totally different standards. It's obvious you've got a bone to pick with the 80's emisions system, and it's obvious you could give two s***s about fixing the real problem. I'm not sure why you've gotten pissed about folks pointing out the fact that your approach really haven't fixed anything. You haven't re-engineered anything either, you just changed it, and you can't support anything you've done either for yourself or anyone else that it's an exceptable long term fix. You don't have to, want to and can't, so it's pointless to argue or get pissed about it. Woody should close this thread, cause it's not accomplishing anything at this point.
 
Rookie2 said:
Woody should close this thread, cause it's not accomplishing anything at this point.

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.

Bear brought his ingenious idea to this board on how to get the EFI system back into closed loop mode. This is -simply- done by bypassing the EGR temp sensor, with the resistor you are telling the computer that the EGR temp is always at the magic number it is looking for. In my opinion this is a 100 times better then driving with the CEL on wit the system in open loop ignoring ALL sensor input.

So far every rejection\objection I have observed seem to come from the type of people who are scared to put anything other than a Toyota bolt on their vehicle.

EGR for dummies
http://www.fordscorpio.co.uk/egr.htm
 
zipastro said:
So far every rejection\objection I have observed seem to come from the type of people who are scared to put anything other than a Toyota bolt on their vehicle.

Hmmm. I know a little about most of those that have expressed an opinion on this kludge of a fix and my observation is that the objections are coming from the type of people that would prefer that something be fixed rather than faked out.

If this was some major expensive subsystem comprised of unobtainium parts then this idea might make sense. But the EGR system is really simple guys. There are only 4 parts plus the ECU and a few hoses and I've never heard of a defective ECU being the cause of a P040x.

You've let a simple system (that you won't take the time to understand) spook you into doing a silly mod that won't pass muster anywhere that has visual inspections of the emissions system.

As for being scared to put anything other than a Toyota bolt.... I only use Toyota bolts because the Cadillac bolts don't fit. However, the Cadillac fluid level sensor is going in the cooling system RSN. :D (Thanks Photoman!) And 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-
 
I don't understand, what's with all this EGR, VSV, blah, blah, blah stuff. Real L/C don't have all that stuff. Oh, wait a second, you guys don't get diesels over there do you. Carry on, don't mind me.:flipoff2:
 

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