2000 Deville Stalling Problem-Need help with diagnosis

[Gwitman]

Hello, I'm new to the forum and I am hoping someone can help diagnose an unusual issue. I searched the forums but can't find an identical problem. My 2000 Deville currently has 109K miles, and started having a stalling problem about a year ago at about 85K miles. Here is what is going on:

1. Car starts up normally and idles fine

2. About 4-7 minutes after starting the car, the engine will abruptly stall. This can happen at any engine speed and load condition. If it happens while at idle or decelerating, the engine has to be restarted and sometimes takes more than 5 seconds of cranking to restart. If it stalls while accelerating hard, it restarts on its own but there is a severe jolt as the car abruptly loses power and then regains power.

3. When the engine is re-started after a stall, the car will never stall again for the duration of the trip.

4. After the car is parked for a while, the stalling problem does not recur if the engine is still hot when it is restarted, but it does occur if the engine is allowed to cool before restarting.

I pulled the DTC codes using the procedure in this forum. Current codes are B0429 (rear climate control), P1621 (Control Module Long Term Memory Performance) and B0077 (Driver side airbag). Several modules are showing historical codes U1000 and U1164.

I saw in the forums that stalling problems are often caused by the crankshaft position sensors, but it seems like those problems should be more random in nature. My car's stalling is very predictable and seems to be strongly related to the engine temperature. I am suspicious of the EGR system since it presumably opens the EGR valve at a specific temperature. With that in mind, I have a few questions.

1. If I want to test the EGR theory, is it safe to just unplug the connector? Will this leave the valve open or closed on this particular car?

2. Are there any other engine computer functions that might be related to engine temperature? Does it change the fuel or ignition parameters after the engine heats up?

3. Anybody have any other ideas what it might be, or what further steps can be taken to diagnose the problem?

If I can't diagnose it successfully I will probably change the crankshaft sensors, but I don't want to spend money/time on that if it can be diagnosed as some other problem.

[KHE]

_{Does the car have the original crank sensors made in Mexico? If so, they are bad. It is not "IF" but "WHEN" they fail.}

[rockfangd]

I second that.

[JimD]

_{Does the car have the original crank sensors made in Mexico? If so, they are bad. It is not "IF" but "WHEN" they fail.}

Too true.

GM's original parts supplier had a quality assurance problem for a few years starting in 2000; the factory installed crankshaft position sensors CAN fail in a way that might not set a diagnostic trouble code.

While nobody here would recommend 'throwing parts at a problem', replacing crankshaft position sensors falls in the 'preventive maintence' category for a 2000 engine.

Purchase the parts from a GM dealer.

[BodybyFisher]

I agree with the crank sensors after checking the fuel pressure. Your problem is not setting a code which the crank sensor will do, but low fuel pressure related to a bad pump or relay also can cause a stall without a code.