Caprice mystery engine skip

[kevm14]

1) Plug wire(s) shorting on steering shaft, causing intermittent misfires. Symptoms presented mainly when hitting bumps. [fixed, new wires, loom, hasn't returned]

I think I know why this appeared to fix the total engine power failure issue. It DID fix a real misfire I was having, but I think the reason it seemed to fix the other problem is because when I installed the plug wires, I probably had to pull on that MAP harness to route the wires.

After messing with the harness this morning, I drove home this evening and there were zero symptoms. It even seemed to run better. Also, I think I can do a simple test to find out if it is MAP wiring or something else in the harness. I will unplug the MAP harness from the sensor and the car should run in alpha-N mode (TPS and RPM only). It won't run well but it will run. Then I will physically manipulate the harness and see what happens. If it doesn't have any issues, then I will probably run new MAP wires. If it does, I can try to probe the signal wire and see if a voltage is present (that's what happened to the TPS sensor harness). Or look at my scan tool.

So I have a plan I guess.

At the risk of being repetitive, almost everything that has gone wrong with this car has been my fault.

[kevm14]

As predicted, this one is rearing its ugly head again in a more serious way. Certain bumps are doing it. Pulling Gs to the right is doing it. It was bad enough this morning that AFTER I went around a corner quickly at about 65-70mph, it was dead to the throttle even after I straightened out for a few seconds. That's as bad as it's ever been.

At work I spent a few minutes in the parking lot to dig into this. A few weeks back, I did a very aggressive maneuver where I turned hard to the right and then to the left (pulling in a parking lot to turn around). I actually got the SES light. It was Code 34, MAP sensor low. Ah, that's something.

At the very same corner mentioned in the first paragraph above, the code mentioned in the second paragraph above happened, again. The light went off after probably a 1/4 mile. I wonder when I will look at this. The good news is, I think the worst thing I will have to do is re-run all MAP sensor wires. I think there are 3 so not the end of the world.

[kevm14]

The SES light came on and went off again. Code 34, same.

[Adam]

Did you re-run the MAP sensor wires yet?

[kevm14]

Turns out the MAP sensor harness looked pretty nasty. So I cut it off and cut the spare off my old engine harness. I also re-ran a new MAP signal wire to the ECM just in case.

I taped everything up and it runs (of course) so time will tell if this happens again.

[kevm14]

This problem has not come back. Almost 303k now.

[bill25]

That is 3K past donuts with no donuts in sight...

[Bob]

Also, we know the only way to fully cure this issue is with an engine swap.

[kevm14]

They say if you live long enough, you'll get cancer. This engine will die of something. Maybe not this engine skip. And maybe not from being driven on the road...

[bill25]

But definitely not from donuts videotaped by a drone???