Hi all,
I have a 94 buick w/ a 3.1L and a 4t60e trans. I am having a stalling issue as I slow/stop for a light, or turn. It is intermittant: it stalls at about 1 in 10 lights, on average.
When I first checked into this, I assumed it was the torque lock converter solenoid causing the problem. But I've come back and read some more and I see that it could also be the idle air control valve.

Here are the (intermittant) symptoms. It only happens at stops and hard right turns. Sometimes there is no problem at all, when I do I have a problem, I'll see the rpm drop from about 750 to 500, and then it will just drop down into a stall. Lately (I don't know if it's been doing this all along), the rpm will occasionally also shoot up as high as 1500 (but then will not stall). The problem does not seem to occur nearly as often in neutral, but I think I've even stalled at lights after putting the gear into neutral.

This has happened without the "check engine" light coming on. What I'm hoping for is that someone knows the symptoms of a bad IAC vs a bad TCC solenoid. I really don't want to disconnect the solenoid, as it is my understanding that involves draining the transaxle. Is anyone out there familiar with this issue?

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I don't think you have a TCC problem. I've only seen the TCC get stuck on the old 125 3 speed trans. If it is the TCC you would probalby have trouble with it stalling as soon as you put car into gear after restarting at least once in awhile. Also I don't think the TCC apply fluid passage has pressure in First gear so even if the TCC solenoid is stuck on the TCC would release in first gear before you ever come to a stop.


I also don't think that your IAC would be bad either because I've not seen very many of these have problems either. It is hard to say for sure what is causing the problem but it could be a vacuum leak or something like that. Maybe a leaking fuel presure regulator. Regulator is easy to check, just pull the vacuum line off of the regulator and check for fuel in it. There shouldn't be any fuel in the vacuum line. You may need to let it sit for a while because it takes awhile for it to show up sometimes. You might just smell fuel in the vacuum line. Also if the regulator is leaking it would probably cause a hard start after running into a store or something because that gives it time to leak and fill up with fuel and when you start the engine it will be flooded with too much fuel.