1996 Buick LeSabre 3.8L randomly dies when cold

This is the the temporary POS that I found for my in-laws to drive two years ago. I told them it would last for two years, but they are pushing it now. For the last few months it will just die. We have replaced the ignition module twice now. Now here's the weird part: it usually dies BEFORE it can warm up. If it doesn't die within the first five minutes of a trip, then you are good to go.

Their mechanic (a good guy, but kind of a hack) wants to try changing the fuel pump. I don't think that's it. All my armchair Google-fu is pointing to the MAF or the crank position sensor. And there are no codes, so whatever is happening isn't making it to the computer.

I know the logical solution is to set fire to the car and buy a Camry, but they just spent $2,800 buying a '95 Roadmaster, so they need to wring the LeSabre out a little longer.

There's a test procedure on the GMForum you can try to check the ICM circuits to see if the Crank Position Sensor is communicating with the ICM. ICM test Armchair quarterback would say crank or cam position sensor as those will intermittently fail without throwing a code. Might also be a good idea to check the harmonic balancer, I had one slowly come apart and cause some weird issues along with hard/no starting, random misfire, random stalling and eventually total shutdown. But my money is on the Crank Position Sensor.

I own a 95 vintage of the same POS. It might just need a new ECM. Check the codes, if there are a lot of codes, then it's probably the ECM.

Mine would fail to start when hot, then sometimes quit when driving. The fuel pump was relatively new. Changing the crank position sensor did not help, but it must be checked. As 06HHR said, check the crank position sensor first.

never had a 3.8 do it, but i've put a few crank sensors in 2.8 and 3.1 powered GM vehicles with the exact same symptoms and it fixed it in all of them.

just for kicks, check all the wiring going to sensors- they can either rub against something, get pinched when someone bolts something back on the engine, or have some rodent decide that the insulation looks like a tasty treat.

I had the MAF go out on my 99 and it didn't act like what you are describing. It would hunt at idle and sometime stall, but it kept doing that regardless of engine temp.

My 2003 impala 9C1 with the 3.8 did the same thing. The IAC (idle air control) valve gets gunked up and sticks. Easy to check and change. It was a cheap easy fix, and still works great 2yrs later! Good luck.