SHINE RUNNER

egr isn't going to cause that or anything like it.these things rarely go bad if at all. what you are describing clearly point to the air flow sensor.if it goes bad and they do more so than the egr it cant tell how much fuel to throw causing the symptoms you describe.its very easy to find a spare just to try.

Flash319

Do a leak down test. I had the same thing when my head gasket was going. 2 cylinders were leaking into each other.

Co_94_PU

iTrader: (-1)

If it was TPS or AFM wearout it would have been gradual not an instant change.

I stand by my recommendation, clear the air chamber to modulator port and disconnect the battery to clear the old codes. anything else is just a waste of time and cash untill you take care of the problems you know exist.

j2the-e

If pulling the fuse doesn't clear the code, neither will disconnecting the battery. Not on an 89. It won't clear because there is probably a short or an open on a circuit that is constantly monitored by the ecu and has a 1 trip logic. NOT the EGR system. He doesn't even know if their is an EGR problem. And I guarantee if there is it won't cause the symptoms being described. Here is something you can try if you dont believe me. Disable your EGR valve and go drive your truck

Co_94_PU

iTrader: (-1)

You sir fail at reading comprehension for some reason, worse than my forgetting his model year.
A disabled EGR is not what he has, he has a malfunction and HE knows it. And there are plenty of threads about the EGR I'm not going to argue with you about it. You want to believe what you believe go right ahead and I'll continue to rely on the toyota engineers.

Also the light not latching on is an indication these are just eeprom errors, 31 should latch the light but isn't so thus it's an error.

To answer the OP's question as to how it still has codes stored.

There is a multitude of power paths and it doesn't take much to keep the memory, this is why the books say to disconnect the battery when pulling the fuse doesn't work. It could be a minor current flow thru an alternate path, across the open fuse junction due to moisture or carbonised plastic insulators,or even condensation. It's also very tempurature dependent, if you live in alaska for instance it'll take much long than say arizona or anywhere in the south. Or it was simply an eeprom error, didn't fully clear the memory correctly.

j2the-e

My reading comprehension is just fine. I can even understand your misspelled words, poor grammar, run-on sentences and lack of punctuation and capital letters.
The truck obviously has an egr issue. But again, like I stated earlier, that won't cause the described symptoms.
Eeprom errors? Light latching? Huh?

Co_94_PU

iTrader: (-1)

Please explain how a malfunctioning vacuum modulator wouldn't cause this problem.

j2the-e

Egr does not lower the combustion temp enough to prevent severe pinging. Trust me. I had an 87 that failed emissions due to high nox. I replaced my egr modulator because it was plugged. My EGR was not working at all for who knows how long. Maybe 2 years since the last test. Anyway, this was in July with temps of 115, and I do a lot of driving at 70mph, uphill, heavily loaded and with a big trailer. Yes my 22re could go 70 uphill with a trailer and the A/C cranking. I never knew the difference in the way it ran. And I owned that truck for over 100k miles

Forrun4fun

I want to personally thank every member that took the time to respond to my request for help. It is much appreciated, and well in excess of what I expected.

After carefully reading everyones input, and analyzing my own results, I am now convinced that the EGR is not the culprit- especially since I removed the valve and only found very minor fouling (thin powder of carbon). I was intially very concerned that I was unable to clear the tiny passage I referred to earlier. The only description I have found of this particular tube has it listed as 'exhaust reference'. (Its the tiny stainlees steel tube that exits the EGR about midway up the neck, and has a vacuum line connected to the bottom port of the vacuum modulator.)

Regardless, I decided to move my area of concentraion elsewhere.

After spending an hour or so doing my normal problem solving technique (which consists of standing in front of an open hood and staring blankly at the engine, lol) I took a trip around the whole bay just wiggling and jiggling conncetions on everything i could reach.

The GOOD NEWS is that the problem has now disappeared completely. The bad news is that I messed with so many things, I have no idea which one was effective in solving my dilema.

Again, using the input from the plethora of knowledgeable individuals on this forum, I am leaning toward a problem in MAF. The boot that covers the wires on the connector was moderately deteriorated (cracked to the point that if you flexed it in either direction, you could plainly see all the wires inside).

I am almost sure the problem will reappear, and this time I will address it one wiggle at a time.

Now I find myself wondering (and dreading) that if the connection to the MAF is faulty, how will I repair the harness without having to create a bird's nest of spliced wiring.....

j2the-e

The stainless tube you are referring to sends exhaust pressure to the modulator. It has something to do with the way the modulator works. I think exhaust comes out if you disconnect it while running.
Broken wires are rare in Toyotas. It happens, but its rare. One thing you can try, is buy some electrical cleaner and di-electric grease. Disconnect the battery first. Disconnect and clean the suspect connector. You can tweak the pins just a little bit to tighten them up. Let it dry. Add some grease and plug it back in.

Co_94_PU

iTrader: (-1)

The EGR vacuum modulator regulates the EGR valve based on engine load(exhaust pressure), when it is not functioning(clogged) the system relies only on the position of the throttle plate(position between the E and R ports).

They key to a visually appealing electrical splice in a harness is to stagger the connection/splices, eg don't cut them all at the same spot to avoid a large bulge.

You can use a large diameter high shrink self sealing shrink tubing to seal the area, or just fill the boot with a silicone type sealer or dielectric grease(available at autoparts stores).

j2the-e

Wrong again! If the modulator is plugged, the egr valve will not operate. Stop giving out bad advice. It doesn't do anyone any good.

Co_94_PU

iTrader: (-1)

FUD! Seriously man call a proctologist or something, you might have something lodged wrong.


http://www.autoshop101.com/forms/h61.pdf
Page three even has pictures for ya. since you are too lazy to read it.

j2the-e

Try to help someone and you get crapped on. Your just upset because I called you out on your BS.

BamaYota1

What is your problem man? You are wrong. Just admit it and move on.

To OP: I am bothered by the fact you can't clear the reference port on the egr. There shouldn't be any problem doing this, as it should be a small tube leading to the larger opening of the egr pipe itself. It almost sounds like the entire egr pipe is blocked between the head and the reference pipe. Have you verified you are getting any flow at the intake?

If you egr is blocked, you can either remove the egr, clean it of all obstructions and replace, or delete the egr system in its entirety. I personally don't recommend this route, but I am not as knowledgable as a whole lot of people who have deleted and swear by it. You might want to search for an egr delete thread. I do know then when guys delete, they have to advance timing and run higher octane fuel to avoid the problems you are having.

Cbar

First off, I am new to the forum in terms of posting. I am a strong supporter of this amazing site.

I have been searching these threads forever, and it seems that this is the closest thread relating to my issue. I need some expert help identifying my idle issue.

I have a 1994 Toyota 4x4 pickup DLX 22RE. It has a new engine, only 35K+ on it thus far. It runs great throwing no check engine lights. However, recently I have noticed my idle "missing" while at a stop light. I will look at my shifter, and it will shudder every 15-20 seconds. Is this a miss? I am puzzled on where to start looking at this issue.

Also, I have no clue if this relates, but when shifting into neutral while coming to a stop, my idle will drop low (400-500 rpm) and then quickly recover to 750 rpm. Is that bounce normal when shifting into neutral. I suspect an EGR problem from reading the threads but I need some help. Expert help. Could this be related to my miss?

I have limited experience with these engines, so please, any thoughts, experiences, and testing methods are greatly appreciated.

Forrun4fun

The problem you describe sounds like a vacuum leak to me - which is common when an engine has been replaced. $10 worth of hose from O'reilly's and you can redo the entire engine compartment.

I am almost positive that my issue was MAF related, even though I originally suspected the EGR system. After lots of research, trial and error, and logical thought, I determined that a plugged/malfunctioning EGR valve could not create the mayhem I was experiencing when some folks remove theirs altogether without issue (if you think about it, a plugged EGR is basically the same as a non-existent EGR).

Were I you, I would zero in on vacuum leaks, TPS, or MAF.