Nasty Electrical Grimlin

[luigisho]

I've undo the bolt that holds everything plugged it, but I don't see the other thing you were referring to. When I jump into the dash, I'll see everything.

Is there anything special or procedural I need to do before I plug the new PCM in so I don't ruin it?

I don't understand this reply.

There is an integrated bolt in the wiring harness plug itself on the engine side. It also came from the factory with a small plastic bracket behind the glove box that held the computer level and prevented it from hanging in place by only the harness plug. Those are the only 2 things that physically prevent the computer from being removed from the wiring harness.

 

[SHO no GO]

I've undone both of those things, but it seems the bracket bolted to the firewall that the pcm sets in feels "attached" and will not allow me to pull the pcm out.

 

[luigisho]

It can be very tight, but as long as the bolt is fully retracted from the computer housing (it is long), it should come free.

 

[BaySHO Performance]

The 10mm bolt that holds the connector to the PCM goes into a threaded knurled nut buried into the plate at the back of the PCM. You can see the end of that nut, having removed the connector. The nut doesn't turn of course. Just the bolt.

 

[zoomlater]

I have pulled ones that seem to be stuck as well and it took a lot of pulling/pushing to get it out. The last one I pulled came out pretty easy.

 

[SHO no GO]

I don't want to break anything, so I'm not going to pull on it too much.

I ran the replacement PCM and it runs the same. It's safe to say that isn't the problem. Aside from wiring, I'm not sure what else to do. I've never rewired anything.

 

[zoomlater]

Might be a wiring issue that you would need to ohm out as Rubydist mentioned previously

Since the codes are in the wrong order, maybe you can clear all the codes and then see what comes up again

The chance of having two bad cam sensors is low, but the car will run without the cam sensor connected, but it will take several tries to start it. Why don't you try disconnecting it and see if it has the same problem with it disconnected. If it's doing the same thing, then I would think you could eliminate that portion of the wiring.

 

[SHO no GO]

I'll try clearing the codes in a few days. I don't want to touch due to pretty extreme frustration with it at the moment. I'll also go and collect wiring diagrams that I can find...

It runs horrible started without the cam sensor plugged it. A few times, I have experimented with giving it some throttle and unhooking the cam sensor then letting it fall to idle, then plugging it back in. A couple of times it resulted in the car idling smooth and normal how it's supposed to. It would idle fine until given any throttle input, then it revert back to its problematic state.

 

[zoomlater]

I know the feeling of frustration, I almost junked my 92 and several tries at fixing it. Ended up being that extra orange seal. Step back and take a breather, and let others here think over what else could be the issue.

Can you tell us more about he car, when was the last major 60K service, how many miles are on it now, any maintenance background you have on the car, etc.

 

[luigisho]

I don't want to break anything, so I'm not going to pull on it too much.

I ran the replacement PCM and it runs the same. It's safe to say that isn't the problem. Aside from wiring, I'm not sure what else to do. I've never rewired anything.

How did you run a replacement PCM without removing the wiring harness? Just turn the harness plug bolt an ungodly amount of times until it must be unthreaded all the way then wrestle with it.

I have seen a few instances where the threaded hole in the computer had detached from whatever anchors it inside (shap/compression fit? solder?) and the hole itself spun inside the computer.

You have a picture of this bracket? Maybe I'm missing something

 

[zoomlater]

Rerun your codes with the replacement ECU and let us know what you get

 

[mikeyp66xxx]

I'm pretty baffled and have tried to search around the forums for this problem, but I could have missed something.
Now for some basic information, I have a 95 MTX that ran well up until this issue occurred. When I was on my home, pulled into my neighborhood, then all of a sudden its running rough and the tach is either sitting at idle or jumping around. After reading around, things seemed to point toward the crank or cam sensor. Since I had replaced the cam sensor due to a failed cam seal, I went for the crank sensor. The problem persisted without getting better or worse. I next purchased a scan tool and ran multiple tests. KOEO was clean while KOER had codes that only pointed to O2 sensors which I replaced(code 136 and 172.) I also noticed at the beginning of the tests when cyl is displayed, it shows 4 instead of 6 on every test. Recently, I have replaced the cam sensor just in case it had problems. The old one was clean of oil and the new one made no difference. I'm now lost on what it could be and I think the old girl has grown tired of the scanner since it no longer finishes tests and hangs on code 136.
Some additional notes, the DIS is grounded and has been replaced as well. She idles with a miss and the tach reads normal when idling I believe until you rev it which makes the miss worse and the tach erratic. She also starts up easy and normal like she usually does.

If you havnt fixed it yet, you are describing what my 94 did a week ago, i changed the voltage regulator on the alt, and its cured!!!

 

[SHO no GO]

I haven't fixed it yet. I accidentally snapped the dash trying to fix the blend door last week, so I have to replace the whole thing now. I found it to be way more delicate than my foxbody dash strangely. I will try the regulator fix once I have it back together. Thanks so much for the suggestion!

It still does the same thing after clearing the codes.

I could get the cable off the PCM. That was easy, I couldn't physically remove the PCM from the car.

Most of the 60k was done when I got the car 2kish miles ago, it did set for a long awhile, so it only made sense for preventable maintenance to be done. It has 206k miles.