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I am at my wits end so I wanted to come to you guys for suggestions. I have a 1990 Oldsmobile Ninety Eight that I’ve owned for years. It’s been a great car overall and I really enjoy the vehicle but if this problem can’t be resolved soon I’ll be forced to buy a newer vehicle.
A few weeks ago, I was driving the vehicle at low speed in town when it suddenly shut off without any warning. The car was running fine before it suddenly stalled. When I attempted to restart the vehicle, it failed to do so. I them tower the vehicle to my mechanic and without doing anything to the vehicle, I attempted to start it out of curiosity. What do you know, it started and ran perfectly! I decided to leave it with the mechanic and they determined it was the PCM (computer). They then replaced it and I picked the vehicle up this past Thursday.
After picking up the vehicle from the mechanic and a $350 Bill for the rebuilt computer, the vehicle ran fine. However, not after 15 minutes of driving, it stalled AGAIN and failed to restart. I them took it back to the mechanic where it is currently being diagnosed.
I wanted to see what you thought could be the cause of this issue. I feel that it’s either a fuel pump, some sort of sensor or maybe a vacuum line issue? I’m at a loss.
Let me know what you guys believe could be the cause of this issue. Any input is appreciated!
Thanks in advance,
Mike
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I had a faulty torque converter lockup solenoid on a similar GM vehicle that caused the car to stall abruptively, and it would not restart until it had a short (15 min) rest, although it only occurred after leaving the freeway as the car shifted out of OD. It’s something worth checking.
That sounds like it would be the cause of the issue! How would one go about replacing this solenoid? Is it a hard job? I’m assuming it’s in the transaxle.
Put a scope on the crank sensor and check it out. Also check the grounds on the ECM at position A12, D1, and D6/7 (black connector).
I’m doubtful about the converter solenoid. You can rule it out by unplugging the 4-pin connector at the transmission and then road test. Keep in mind that the overdrive won’t work while this is unplugged.
Thanks for the suggestion! The converter solenoid seems like a likely culprit to me however considering that the ECM/PCM is brand new and the crank position sensor has been replaced within the last year. However, considering the history I have with O’Rielly Chinese parts, the sensor could be found bad even though it’s only roughly a year old.
Never discount the fact that any part can be bad out of the box or fail prematurely. The ECM can be bad too. The majority of repair work I did as a young mechanic was on 1990s GM 2.8L and 3.8L vehicles. I once went through 4 replacement ECMs for a 1992 Buick before I got one that worked properly. ECMs from this generation 3.8L vehicles are extremely failure prone. An interesting trick that we used to do in the shop was take a small hammer and tap on the ECM while the engine was running. If the ECM is bad, the engine will buck, sputter, or stall. If we could tap on the ECM with no effect on the engine, then we assumed it was good and moved on to the next most likely culprits which were the crank sensor and ignition module (The crank sensor signal goes straight to the ignition module, not to the ECM, by the way).
Thanks for the response! I’ve been warned about the failure of the 3.8 but ive never heard about the PCM issues. Considering it’s such a primitive computer controlled module, I can see where it would be bad. I love this car but I am at the point to where of it can’t be fixed I would be forced to but some German or Asian car which I don’t want to do.
Just went through this last spring with a 1990 cutlass with only 30k original miles! Saw same symptoms, stalling after running. swapped cranks sensors and everything. What the culprit was? Worn fuel injectors. Free cheap test: Pull each of them and test for resistance with a multi meter. We had 2 of them giving infinite readings! All injectors should have the same reading. If they can’t get the signal to fire, car no run. And it seems the resistance got worse when the engine would heat up.
Check this video out from youtube for how to check the resistance – Readings should be 12-16 olms. Any less or more, try swapping. Here in Canada, they actually have a returnable core on them :). To see how to test, see the video below at about minute 2:20
It was my dads car and we spent 3 days sorting this out, throwing sensor parts at it. When we put 2 new injectors in for the bad ones he drove it cross country after that. It works great.
Also, did you check to see if any obd1 codes were present? Just need a jumper wire to read them. In our case there were no codes which made it all the worse for troubleshooting.
Hope this helps. Good luck! 🙂
UPDATE 9/1/17: So I picked the car up from my mechanic yesterday. He was kinda vague with me but told me that he had found a bad/unhooked ground wire that was causing the intermittent stalling problem. However, he told me that a new issue arose. Apparently the AC compressor is “drawing too many amps” and causing fuses to blow repeatedly? I’ve heard of blower fans going bad and blowing fuses but not a compressor. I’ve had multiple compressor issues in multiple cars over the years and typically the clutch goes bad or it disintegrates from within, but ive never heard of an electrical issue affecting a compressor. Anyway, just wanted to update you guys and get your take on this.
Thanks,
MikeThere are 2 kinds of compressor activation. The less common kind uses a solenoid to change a swash plate’s angle. The much more common kind, which you almost certainly have, uses an electromagnetic clutch. In both cases, the compressor itself is mechanically operated by the engine and cannot itself draw current.
A compressor clutch going bad can draw excessive current, though it’s more common for them just to seize up or stop engaging.
I would verify this yourself or get a second opinion. If the clutch is the problem, you may or may not be able to buy one without the compressor. If not, get a compressor from a junkyard and take the clutch from that.So just to clarify, was the ground indeed the issue? It does sound strange to me, since the problem you have (had?), sounds very similar to one my Dad had, and during my feverish checks on the web, a bad ground was never mentioned as a cause.
For the heck of it though OP, I do have access to every TSB for these GM cars here so I can check into this more if you are still having the issue. Just putting that out there!
Not to discount the possibility of an injector shutting down a PCM, but I can say for sure a ground fault can cause all kinds of problems with any car. I recall a 96 Nissan Altima that had a no start once just because a battery ground was just bolted to the wrong place on the block. I diagnosed a 98 Dodge once that had a wiring harness burnt onto the exhaust manifold. It burned away the loom and the PCM ground wire within. The wire slowly rubbed away at the same time on the exhaust manifold allowing the PCM wire to use the manifold as a new ground until the wire eventually broke. I showed my customer by grounding that burnt wire on the exhaust to get it running again. I had a bad ground once on an 02 Buick LeSabre cause a hand full of codes after I changed the engine in it. I didn’t see that most of the strands were broke at the ring terminal and that was enough to affect a lot of sensor inputs and give me one unhappy customer that was sure we sold him a junk engine.
I know Scanner Danner has a good video on his YouTube channel that shows early GM fuel injectors being chronic failure parts. I think it was for a 1st generation 3.1 litre engine but I remember all of GM’s early fuel injectors were failure prone. Find it and watch it if you can. You might be onto something yet.
@ the OP, when your mechanic said it’s blowing fuses, did he mean that it’s repeatedly blowing the fuse for the AC compressor circuit or is it blowing fuses that power other circuits as well? If it’s blowing fuses that power other circuits, then I’d consider a short to ground in the circuit somewhere before the compressor. Otherwise, the coil in the compressor itself could very well have shorted out too. What I saw of the wiring diagram showed that the AC compressor circuit also powers the rear defrost and the electronic ride control which means there’s more than one way for this circuit to possibly be shorted out. I think a real easy thing to do for yourself is to do a visual inspection of the wiring harness. Most of the short circuits I’ve diagnosed lately have been due to a harness getting burnt on exhaust components. Even if I’m wrong, looking is free. If you’re in a rural area, look for evidence of rodents eating on wires too.
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