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If anyone has been keeping up with me, I have been having quite a bit of trouble with my '90 3.1L lately. New ECU, ICM, tune up, fuel filter, etc (most problem sources eliminated). Here is whats happening:

The car will start and run fine in the morning (cold start). My problem is intermittant (will do this once every 3 times or so), but everytime I try to drive the car, I can get pretty much the same distance from my house before the car goes into "stupid mode". The car will go from normal to wanting to stumble on itself. Once it starts acting up, I can hold the pedal in a steady position (steady speed) and the car will start bogging/sputtering and the RPMs will slowly drop and the car will slow down. If I left off the throttle, the engine levels out, but as soon as I get back on the throttle it starts again. The only way the car seems to want to run normal is either if the throttle isnt being pressed or if it is almost floored. I was reading around about how the 3.1 is prone to EGR problems, but I don't have a check engine light on. If anyone has ever had a similar problem, please help. If I can't fix this, I'm gonna have to sell the car.

Try unplugging the TCC from the trans. It is the square plug on the "front" of the the trans about 12" under the air box/intake.

It could be the problem, It's a common issue on 3t40's.

The other thing is to pull the EGR and clean the crap/carbon out of it.

Or just hit the damn thing with a hammer a couple of times and see if it clears up for a while.

I had a 4.3 I had to beat on a couple times a month 'til I had time to deal with it.

G/L

Asylum has got some great info there. 3X00 is the trans master here, feel free to ask him also. I would hate to see you get rid of your car.

I think I might have something going here with the EGR. I'm gonna take it off and see if it is dirty tomorrow. I know it is not transmission related: 1) The TCC solenoid is new and 2) you can tell that it is definitely an engine problem.

Im gonna try the EGR thing and see what happens. I really dont wanna get rid of my car, so I am hoping I can fix this soon.

Thanks guys...

The EGR should only be working when at cruise. Try to unplug it and see if that does anything. Also try some Heet in the tank to make sure there is no water in there blocking the pick up. I've had that happen to me before on another car. You will have to let it sit overnight for the Heet to mix. Does you fuel pump make a noise? If it doesn't it could be bad.

I think I finally figured this thing out! The car started acting funny again today, and while I was going down the road I put the car in Neutral, and the engine was acting fine. This in my mind points towards a tranny issue. When I put the car back in drive, it starts up again. The car wants to surge forward and slow down under steady throttle and steady speed. The only thing I can think of is that the TCC solenoid has gone bad again. Even at 50mph can the solenoid mess with the car like that?

The only other thing I can think of is that I noticed right below the ignition module on the drivers side I have two exposed (what look like transmission) wires. They are both about 10ga copper wires, that I am pretty sure to be grounds, but they have no insulation covering them.

Any ideas?

Walmart sells some liquid electrical tape. Clean the wires off and brush that stuff on. Are you sure that those wires go to the trans?

At 45mph the converter will lock up.
Are you going up a hill when this happens?

I would have to go look more in depth to see where the wires go, but I'm pretty sure they go to the tranny.

As for the converter, when the car is acting normal it will lock the converter up around 40-45. Whenever the car starts acting odd and wanting to fall on itself, I can be driving on flat ground, a hill, etc. (doesn't matter). It has to be something wrong with the transmission, because when the car starts acting up, and I shift into Neutral, the engine runs fine.

Did you try to unplug the TCC?

Actually I did unplug it right after my previous post. I drove the car to work and it was still acting up. I talked with a mechanic that normally comes to my work and he said that I might want to try replacing the throttle position sensor or the fuel pressure regulator.

The best that I can come up with now is that this is only happening when the car is under a load. You can rev it up fine in neutral when it is happening, but it runs like crap when its in drive.

I am at the point where I am literally gonna have to park the car and just buy something else if I can't fix this.

You can keep throwing parts at it but the best thing to do is try to get a datalogger you can borrow, that way you can watch spark, injector pulses and all that other jazz to see what may be happening. I have an obdi logger but I don't remember where it ended up, my ex's father had it for a while.

Is there a relay for the TCC?

Not that I know of, IIRC its controlled directly from the ECM

Hence why Unplugging the Trans plug is the EASIEST way to debunk that being the issue.

Yes you are very right, no relay. Pulled out the diagrams and the only things that I see are two switches. One for the brake and one for the power steering pressure. The PSP switch is connected to the transaxle position switch. I don't see how that could cause any trouble.

John, I can't remember if you changed the fuel filter, did you? From the way it sounds it could be just that or water in the gas. Did you try some Heet?
I have had a clogged fuel filter and the car acted the same as yours. Water in the gas can act like a clogged filter also. The only way to get fuel to the engine is a low flow or a high flow(idle or WOT). It takes a little time for the water or the dirt in the tank to get to a point where it would block the flow. That is why you can drive for a short time and then you have trouble. Anytime the fuel is blocked in any way that will cause a feeling like a surge. A TPS that is bad will make a high idle(save your money).

The fuel filter is probably about 3 months old. I did try what you said, and I dumped a bottle of heet in the gastank, with no noticeable results. Apparently unplugging the transmission plug has no effect (other than the fact that the converter doesnt lock up).....The car still acts weird whether it is plugged in or not.

The fuel pump is functioning from the sound of it (the pump and sender were installed about a year ago), and the car seems to run totally fine at idle and for the few minutes I drive the car.

I literally switched out the ECM like 4 times with reman A-1 computers, just to make sure I didnt get a bad one. I also re-replaced the ignition control module to make sure it wasn't the problem again.

Is there anyway a coil can be causing the problems I'm having? The coils are pretty much the only thing that havent been changed, but I dont see how a malfunctioning coil can be doing this if the car is running fine at idle or WOT.

I'm planning on picking up a used S-10 here in a few weeks, so if I can't fix the car, I would certainly be willing to sell it at a good price to someone on the board if they are interested.