Nasty Electrical Grimlin

[SHO no GO]

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.

 

[zoomlater]

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.

Did you try pulling codes by counting the flashes on the check engine light. How old are your spark plug wires?

 

[SHO no GO]

Did you try pulling codes by counting the flashes on the check engine light. How old are your spark plug wires?

Plugs and wires have less than 500 miles on them. And I didn't do the jumper method since I figured a normal scanner would be better.

 

[zoomlater]

Try pulling the codes with the jumper wire and let us know what you get. I had a car that had no codes, but a miss around 2500rpm, my fuel pressure gage was double what it should have been. Replace that and wires, it was almost back to normal. It started and idled normally

 

[luigisho]

My first guess is wiring or computer. Maybe idle air control or another failed cam sensor. But I am thinking you can not get sensor and driver data to synch up.

AS above any fuel, spark, air thing is suspect at this age. as can wiring

 

[zoomlater]

Since you changed the cam sensor a couple of times, make sure there is only one orange seal inside the cam sensor connector. They sometimes get stuck in there when you are swapping them and you end up with two of them in there. It will connect, but makes an intermittent connection. I almost gave up on one of my cars until I read that on this forum and checked.

 

[rubydist]

Your symptoms point to the cam sensor. I agree with the above advice to make sure there are not two seals in the connector, but other than that it would most likely be a wiring harness issue or a pcm issue. I have seen both of those. Can you find a known good pcm to swap in for a test?

 

[SHO no GO]

I've caught the cam sensor connector rubber hiding before. There's only one in there.
I do not have access to a spare PCM and it might be awhile before I can grab one.
Also I used the jumper method and it shows more codes. In order for me not to leave this up to chance, is it possible I link the videos to what the car gave me? It seems to be a lot.

 

[luigisho]

you should invest in an obdI code reader for this vehicle. It is easy to lose count and such things. and chasing codes can be time consuming

https://www.amazon.com/INNOVA-3145-Ford-Digital-Reader/dp/B000EW0KHW?th=1

These are available locally at parts stores for about the same price.

 

[SHO no GO]

I have one. I've used it. Someone recommended I use jumper method anyway.

 

[zoomlater]

There is a way to link a YouTube video and post the link here

 

[SHO no GO]

KOEO

KOER

I haven't looked up or broken these codes down yet. She's not happy.

 

[luigisho]

I have one. I've used it. Someone recommended I use jumper method anyway.

I haven't had issues with that particular item. There are others that may have issues but that model has been fairly reliable.

 

[zoomlater]

KOEO

KOER

I haven't looked up or broken these codes down yet. She's not happy.

So for the KOEO, your stored codes are 212 and 217, Loss of ignition signal/spout and DIS coil #3 failure. These are the second set of codes, I didn't see any current codes as they were 111 111. Did you ever clear all the previous codes before you started having issues?

For the KOER, the codes I see are 172, 136, 538, 536, and 521. Did your code reader see these codes. I have the same Innova code reader and so far its been working for me, but I thought you mentioned it stopped working at code 136. That is why I suggested you count the lights. Several of the codes are saying things were not done during the test. The last one is Power steering pressure switch circuit fault.

 

[rubydist]

First thing, this is very strange because the codes are supposed to be presented from lowest number to highest number and then repeated. While they are repeated, they are not displayed in order from lowest number to highest number. This makes the pcm suspect in my mind.

If we assume that the codes are correctly displayed (just not in the correct order) then:

212 tach signal erratic - this will always make the engine run crappy and must be fixed. Since you have changed the cam sensor multiple times, as we said earlier there is either a wiring issue to the cam sensor or the pcm is bad. The engine will never run correctly while this code exists. Nothing else after this particularly matters until you fix this one.

217 coil 3 circuit failure - I have seen this multiple times and it has never been a coil problem, it has always been a DIS problem. If you check the connections to the coil and the DIS and they are all good, then the DIS should be replaced.

136 lean front oxy sensor not switching - this could be due to a vacuum leak or a bad oxy sensor. If they are not pretty new, I would replace the sensor.

172 lean rear oxy sensor not switching - same as above. Since they are both reading lean, that increases the chances that there is a vacuum leak causing the codes.

521 - is not on my list of codes - it appears to be related to the signal from the oil pressure switch on the engine. This could be a sensor issue, but more likely a wiring or pcm issue.

536 brake on/off switch open or shorted - iirc, this shows up if you did not step on the brake pedal at the correct point of the test, so as long as your brake lights work I would ignore this.

538 no goose test - this means you didn't mash on the gas pedal at the proper point in the test, so you can ignore this one.

So your first order of business is to get rid of the 212 code. Either get a wiring diagram and ohm out the circuits from the pcm to the cam sensor, or else replace the pcm. In my experience, your odds are about even as to a pcm issue or a wiring harness issue.

 

[SHOZ123]

On my '93 I had the coil connector orange rubber seal interfered and sometimes it only ran on 4 cylinders. I took it out completely.

 

[BaySHO Performance]

521 is Power Steering Pressure Switch did not change states in KOER. The steering wheel wasn't moved from lock to lock during the test.

 

[SHO no GO]

Sorry for the long absence, but now I'm tearing back into this. The reader works fine on the other cars I've used it on. This car seems to fight it for some reason. I haven't cleared any codes since this issue presented itself. As for the Power steering and Break test, those can be ignored. I couldn't distinguish the flashed that prompted me to do those.

I have a PCM on the way. As for the DIS, both of the ones I have do the same thing. I also ran the car with and without the orange rubber seal on the cam sensor, same result.

When I tried to remove the old PCM, it wouldn't come straight off after removing the hanger that was suspending the back of it. I feel it's stuck on the bracket up front some kind of way. I'm going to pull the whole dash anyway to replace the blend door since that's already dead. Found it a little strange it wouldn't come out like I've read on the forums.

Thank you guys for all the help, advice and code breaking. Hopefully this PCM next week does the job. Yall will be the first to know.

 

[luigisho]

The wiring harness plug that goes into the computer from the engine side of the firewall has an integrated bolt in the middle that screws into a threaded hole on the computer to maintain contact with the pins during the jostling and vibrations that are normal for a car. There is a knurled roung thing that you turn in the middle of the harness plug on the engine side of the firewall.

 

[SHO no GO]

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?