In late July I had both the ignition switch and the mass air flow sensor replaced on my car. Coincidental I guess that both started to cause issues at the same time. ??
I got my car back and drove it for almost 2 weeks without issue. Then one afternoon I felt what I describe as a pulse or a slight surge. When the MAF was going bad, the RPMs would drop and then recover. This was a little different feeling though. A few minutes later, it happened again and the TRACTION OFF light came on. I had a low tire so that light was on and I just thought it was maybe related to the tire somehow. Then the SERVICE TRACTION light came on.

I continue driving, now out of the city and on country roads. The engine starts running rough, almost dying, then recovering. The LOW FUEL light came on and then goes off (was not low on fuel). The CRUISE CONTROL light flashes on then off (cruise was not on). The Battery light flashes on and then off. The Service Engine Soon light came on .... I think that one stayed on.

I get to my destination and turn off the ignition, wait a minute and start it again. It dies. I try again and maybe once more after that. The last time, it was fine, only light on was my LOW TIRE light. Later that evening, I drive home and the car is perfectly fine, not a problem.

Several days later we try to get the car to the mechanic's shop, but I can't get it started or can't keep it running. Hubby has some better luck. He got running once, no gauges working, engine very rough, it died. Started it again and it was fine, all gauges working. Mechanic has issues too getting it started/keeping it running. Sees the old MAF in the backseat and puts it back in. Car runs fine. Puts the new one back in, car has issues. He's convinced that's the issue so we get a replacement MAF and I think I'm good to go again.

But I'm driving it home that night and I swear I felt that little pulse again. The next morning I start it and it promptly dies in the driveway. Totally frustrated, I didn't even try to start it again and instead just took the old truck.

I was supposed to take it back to the shop but we decided to delay it. I've been afraid to drive it to work but we keep starting it and letting it idle or drive it around the block, or very short distances. No issues for me, but hubby started it once and had no gauges working at all. The Low Fuel light came on because the gas gauge wasn't registering. He said the engine ran fine though. He drove it around the block without problem, except for lack of gauges (all of them, I think). He started it again, and they all came back.

So any clue what's going on here? I googled stuff and found info about the PCM. Sounds like that might be going bad? I'm sure my mechanic and his guy (the one who really does the work, lol) can figure it out, but I'd like some opinions. Sorry for the long post but wanted to include any details that might be helpful. Oh, I got the AC recharged at the same time as the ignition switch and MAF. It's now NOT blowing cold. I think that might be a leak rather than a sensor/thermostat issue though.

2001 SS with 111,000 miles. Thank you for any input!

 

May be way off but check this first. PCM or BCM could be going out or could be another ground, but I don't have any experience with your multitude of issues. They sound like an intermittent ground failure.

This one is an easy first step that has helped several: https://montecarloforum.com/forum/mo...problem-60012/

The PCM is under the air filter box, there's a ground down there to check/clean up. At this point, clean up any grounds that you can find. As I recall, the switch harness has a latch, so that wouldn't likely be a loose connection.

Hook up a scanner; hopefully, with your fleet, you have one that reads live data. With all those issues, it should have some codes stored.

 

Thank you Glen for your response. I called my mechanic last Thursday and let him know I was still having issues. He thought it might be a PCM or BCM issue but was going to look into the symptoms more for me. Said the PCM shouldn't affect the driveability of the car...then he corrected himself and said well the PCM could affect the BCM. Ugh. Sounds expensive. Still hoping for a ground issue.

Didn't really drive the car this weekend like I said I would. Husband moved it once - took multiple tries to get it started/running properly. I had the same problem two more times. Since I was tired of playing musical cars in our driveway, I decided to just take it to the mechanics shop again. So he has it again - told him to get to it whenever. I love this car but this is very frustrating.

 

What was fixed?

 

My mechanic was never able to 100% pinpoint the cause of the trouble. Sometime it started and ran just fine, other times not -- running rough, barely able to keep it going, he said you could just smell the raw gas coming from it. They tried banging and tapping on various things (he explained why) while running badly with no change. He said even when it was messed up, it wasn't throwing any codes. He was leaning towards PCM or the new ignition switch. I still had the original ignition switch, so we decided to swap it back. Then it started and ran for him without issue, tried it several times. I picked it up Friday morning and drove it several places. I think it was fine. A couple of times it seemed like the battery light may have stayed on a second longer than usual or it had a very slight hiccup while starting .... or maybe I was imagining it all.

So I'm not sure what to think now. My husband asked if I was going to start driving it again, and I said yes. Buying diesel fuel for a 25yo truck is killing my weekly budget. I guess if it dies again while driving it (like while going over RR tracks), I need to put it in/out of gear, jiggle the key, rock the car, whatever and see if it starts again. I still think the ignition switch is going bad but obviously the computer does NOT like the one we put in it.

Still stumped.