How to diagnose a stalling problem?
 

Hi everyone!

I own an 87 Buick Lesabre Limited Coupe ( http://www.cardomain.com/ride/242436...-buick-lesabre ). I have driven it for the past 6 years with no major problems, but just now it has begun to have a stalling problem. The engine just shuts off at random times. Doesn't matter if you're at a red light or driving in traffic. She will stall, then after 5 minutes will start up again, and stall again. So, I took to it to my mechanic & he changed the ignition module & mass air sensor. I picked it up, and the 'Service Engine Soon' light went on, and then she stalled a few minutes later. So, I drove her back to the shop (stalling several times on the way), and my mechanic changed the crank position sensor, and she still died. He read the trouble code 42, so he changed the ignition module again. I picked her up yesterday, and she made it home without stalling, but the 'Service Engine Soon' light still goes on after 5 minutes of idling, which leads me to believe that the problem lies somewhere else. Could it be an electrical problem (wiring, fuses, computer) that is causing the 'service engine soon' light to go on & the car to shut off? What else could it be? Any insight you can provide would be appreciated. Thanks!

Code 42 means you have a problem in the EST (Electronic Spark Timing) circuit. An open or ground in the EST circuit will stall the engine and set a code 42. The engine can be restarted, but will not run on module timing.
A thorough check for an open wire or a possible pinched wire in the EST circuit system is most likely the cause. Nice pix and agree car is in beautiful shape.

Thanks for the reply & for your kind words! My mechanic basically did everything that he thought it would be. He said that if the problem is not solved, he suspects that it could be a wiring problem, so I'm gonna take her to an auto electrical systems specialist tomorrow. Hopefully, they will be able to check something like that..

If they can't help you maybe I can supply some info that would make the checkout of the two wires involved a little easier.

Thanks! Whatever info you can provide is most appreciated. I personally don't know a lot about cars (as far as doing the work myself goes), but I do like to do the research and find out what I can about these kinds of things. I just let her run for about 20 minutes and the SES light goes on and off regularly while idling, although she didn't stall.. Still I am kinda nervous to drive her very far until I can get the problem solved. :O