94 LeSabre stalling/won't start

g_man420

I have a 94 LeSabre, 200,000 mi. I've had it for a little over a year now. Motor still runs strong...... when its running. When I bought it I had to replace the crank sensor and it then started right up. While I was at it I replaced the starter, MAS, TPS, O2 sensor, plugs, plug wires and the ECM. And for all my efforts..... it stalls randomly at any speed, idle temp whenever. Then suddenly won't start. Sometimes it will eventually start but is presently not starting and appears to have no spark. I've heard that the prob may be with the computer, but idk and can't read the codes without taking it to the dealer. Oh.... also replaced the fuel pump and filter. Its no longer a $300 car! Wich is what I paid for it. But when running, it runs great and I've never had a better car inbthe snow, so I hate having to thinknabout getting rid of it. Anyone have any constructive suggestions?

imidazol97

Was the crankshaft position sensor one that required setting to a specific air gap (like spark plugs)? IIRC there was a switch from one that required that set when installing to one that was predetermined by the bolt in layout.

What you need to do is use a voltmeter to look for voltage from the CPS when the engine is cranking to be sure it's working. Your symptoms sound like that or a bad connection at the ignition switch (not the key cylinder/lock cylinder) the actual switch on top of the steering column below the fascia that hides it. It is operated by a rod from the ignition cylinder. The contacts inside wear from the constant making and breaking as key is turned along with the corrosion due to the spark when making/breaking contact. I recall some would lose connection. The symptom often included engine shutting off due to vibration causing the poor contact to break when hitting sharp bumps on road. Did yours do that?

Another place is the ignition spark module. Not sure of the name. It's the flat metal box below the 3 coils. The connector on the front can lose contact--it's in a bad environment. Try removing it and reconnecting it after inspecting the contacts. One of the contacts that gave trouble from posters reports long ago was the ground connection lost good contact there shutting down the ISC or whatever the acronym is.

The signal from the CPS goes there as a couple of timing feeds, IIRC, and the module uses that to process the spark commands going to the computer. This item is cheap to replace from a pick n pull just as a way of checking. I believe the module is moderately expensive to buy new. Check rockauto.com for yours, and then click on the blue part number to see all the other GM cars that have the same module. Makes it easy to find one in a pick and pull.

There used to a be a thorough diagnosis for the spark control module on the net. It requires facile ability with a voltmeter to determine if the inputs are correct from the CPS IIRC. If I can find it in my old browser, I'll add the link to it.

Good luck if you're still working on this as it's been a few days since you posted the question.