94GT 3100 stalling out trouble restarting!!!

My 94GT 3100 V6 is having issues:

First it wouldn't want to shift out of overdrive. Sourced it to a bad TCC. Disconnected it and fixed the shifting problem temporarily until I can replace the TCC.

Secondly, it started this fun little adventure....

When the engine and trans are cold, all runs just peachy. However, once the vehicle reaches operating temperature, it starts to hesitate/miss, acting like it is starved for fuel. No matter what I do this cannot seem to be avoided. If I shift into neutral and feather the gas, sometimes is prolongs the stall, but only briefly.

Now when it stalls out, I have one heck of a time getting it restarted. It will turn over and fire immediately, but stall right back out. If I keep at it it will eventually start and run, but it runs like crap...sputters, has a really hard time staying running, stalling in the end.

I keep this up for about 10 minutes (god help my starter) and it will smooth out for a while, usually enough to get home. I'm wondering if my cat is blocked up?

It hasn't thrown any codes the entire time, I got rid of the +4 plugs and went back to the ac delco, changed my fuel filter, cleaned my TPS, IAC, etc...changed a cracked coil pack.

The car doesn't miss, it just sputters really hard. This is why I am thinking cat. When the car stalls, I can hear the fuel pump running for a second or 2 before I retry to start it again.

Anyone, have any ideas?

I need help with this issue. I've read some stuff on the 3100, and seen mention of a MAF sensor on the engine, but everything I've read says that the 3100 doesn't have one.

Any and all help is greatly appreciated, as I have a 30 mile commute through heavy traffic to work and home both ways, and am growing tired of the stalling out when I can't get off the damn road...also its made me late for work a bunch of times and I don't have any other means of transportation.

so again, HELP, PLEASE!!!

There are several things I would look at replacing. First, how many miles on the car? You may have bad fuel injectors. I had a 2.8 that did exactly the same thing. I replaced the injectors and the problem went away. Rather expensive but cured the problem. It appears that the injectors, when they wear develop an increase in resistance and will start to stick especially when the engine is warm. It never did throw a CEL the entire time although I eventially changed the computer anyway. The other item I would check is the Crank Position Sensor. Although it does not give the symptoms you describe it could be a part of the entire issue. Finally, if you have not done so you may want to change the plug wires, they can go bad and cause problems, they are cheap insurance against misfires. Hope this helps!

I have 150K on the car.

I changed the plugs and wires out yesterday (lost the platinum +4s) and still the problem described earlier. It stalls when I put it in reverse now...though not every time.

How do I check the crank sensor? I am fairly adept as working on cars, but that one I know NOTHING about, so any and all help would be great.

Also, I'm not sure what injectors to get if I replace them. What flow rate are the stockers at? I'm not interested in anything but getting it back to stock.

Someone suggested to me unplugging my O2 sensor and seeing if the car does it when it warms up and enters "closed-loop" mode. If not then the sensor is most likely bad. However, I thought that a faulty O2 sensor would throw a SES light?

The stalling only happens in reverse once I get it restarted. When the car initially acts up, I can't get it running for anything, but when it does smooth itself out, it stalls when I go into reverse only.

Could the problem be the Catalytic Converter? If so, is there a way to check it?

Thanks for the advice so far...I'm going to see if I can find a way to test the crank sensor fairly easily, if one such way exists.

May be the ignition control module. I was told that when the engine gets to normal temp and the module is bad it may stop working. replaced it on mine and it wasnt it. was the crank position sensor. but mine did it when the engine was cold too. so maybe the cps. hope this helps some.

Try replacing the ICM first to see if that is where the problem is. Due to the fact that you replaced a cracked coil the ICM may be bad too. It is easy to replace.

As for the CPS there is no way to check it just replace it without a Tech 1 scan tool. The 3.1 is located on the side of the block and usually takes a special tool to pull it out. If you are not familiar with removing this I would have a mechanic do it for you.

When I took it to my mechanic yesterday afternoon, he put it on the computer and it had a soft code 34 (MAP SENSOR) stored. He cleared the code, and we took it for a ride with the computer hooked up...of course, it acted just fine...no problems, everything returned normal readings as far as the sensors went.

He told me to take it home and let it cool down completely, then take it for a ride...he thought it might be a problem switching into closed loop on its warm up cycle, because it only happens when I've been driving for a while (maybe 10 miles) at highway speed, 55 or up.

Last night I took it out to see what it would do, and it ran perfect, except for the left rear brake hung up (another story, got that fixed along the road) until I was almost home and disengaged cruise control. Once I stepped on the brake to kill cruise, it took about 30 seconds before it stumbled and stalled. (speed was still 45 mph, so the TCC being engaged should have no bearing...if that is the probelm, but it can't be since I have it temp. disconnected during this troubleshooting period). I pulled off the road and it started right back up and idled fine...as soon as I put it in reverse, it stalled. If I went straight to drive, it ran fine.

If I went from P to D to R, it stalled too...after a little of this (I needed R to get back on the road to get the rest of the way home) it finally stayed running when I went into R. After that, it got me home without too much grief (it stumbled a little bit pulling out from a light, but I gave it a little more throttle and it cleared itself up.

I have no choice but to make an attempt to get to work today (can't afford another day off) but I will be checking back here throughout the day from work.

I still am looking for any and all suggestions. I'm kinda hoping it stored the soft code again (stopping at the mech. after work), which tells us that the MAP sensor is bad (I'm hoping that's all it is, though I somehow doubt it)

I'm also going to change the ICM tonight hopefully, AAP has one in stock here for $80, unless that would turn out to be a junk one, in which case I don't have the $300 for a new ICM (could I get one from a scrapyard or is that not recommended?)

Thanks for all the advise so far.

One more question, how hard it is to change the CPS?

Was told to consider changing the Crank sensor, so how tough a job is this?

Thanks!!

You are better off buying a new ICM. It should only be $80 for a new one.

UPDATE!!

The car quit on me again going to work this morning. Wouldn't restart this time. I called AAA and then called my mechanic...had it towed there.

When we got it there off the roll back, of course, it started right up and ran like a friggin' top. Took it for a 30 mile ride, no problems...got it back to the garage, popped the hood. He touched the harness that feeds the injectors and BAM, it died.

Started it back up, he moved the wires again, and once again BAM, it died.

We took the intake plenum off to see if we could find a short or broken wire and what we found was that the feed wire (the pink one that feeds into the 6-into-1 injector power connection was corroded and only together by 2 strands. As soon as he moved it, the wire broke. We cleaned up the wires and re-did the connection (w/solder and heatshrink), and put everything back together.

It started up immediately and ran perfectly. It was stalling when I would shift into reverse before we took it apart, and afterwards, it didn't even skip a beat. Even when we did the "wiggle test" on the wires again.

He rechecked the computer for me and no codes were present, hard or soft. Tried to clear the codes anyway to be sure.

Since then, so far so good. It ran around all day no problems...to work, home from work and on some errands I had to run.

He thinks (my mechanic) that the connectoin was weak enough that when it would heat up it was too much for it to handle and would arc and send a signal back to the computer, shutting down the motor as a safety precaution. (don't know if such a safety is programmed into a computer, but knowing what I know about electrical, it makes sense to have such a safety, spark and fuel...not good outside the combustion chamber...and being that near the fuel rail...you never know)

Irregardless, the car is running perfectly thus far...the test will be the next couple of days to see if it acts up.

Thanks for all the other tips and advice...I'll be sure to keep it in mind if the car acts up again.!!!