Blown, while reading your forum issue, I recognized those exact same symptoms and conditions that I experienced in my 1990 SC 35th back in August 2007 when it reached 157,235 miles. After the violent episodes occurred two days in a row, according to my records I took my car to the Ford dealer on 8/3/2007 and they changed the camshaft position sensor and said I was good to go. After driving 15-20 minutes the next morning on my way to work, the engine started the same wild bucking, tachometer bouncing from 0-6,000 rpm, coughing, etc. as before the repair. I took it back to Ford on 8/7/2007 and they replaced the crankshaft position sensor, ECM unit, and stator at 157,251 miles. Apparently, that was the fix because I haven't had the problem again up to this date at 210,832 miles. Hope this helps and good luck with your SC because you definitely have the right members helping you now.
Electrical issues ??
- Thread starter blown
- Start date
No, at this point I am throwing parts at it. As far as I can tell this (the ECU) is the last in line.
Thank you for your insights. I had not considered the stator.The company I got the ECU from is going to exchange the one I just got (that ran worse) with another.
Here's hoping !
So the harness that connects the crank, cam sensor,spout connector & DIS to each other passed the wiggle test or you took it off & checked it for continuity on all circuits? Not sure what nj2251 means by stator? The trigger wheel on the harmonic balancer for the crank sensor possibly? It is a stamped piece of metal that tempeture or 20 minutes of running would not effect. It either works or it doesn't. Maybe the crank sensor wasn't gapped properly & the wheel is striking/damaging the new sensor.
I never understood why the stator was replaced either, since I thought that was part of the alternator. However, to further check I retrieved the Colonial Ford service advisor sheet from my very thick Tbird Repairs file and found the technician repair report attached. Along with the crank sensor and PCM, the stator assembly is also listed as a part changed. The stator assembly part# was E9SZ-12A112-A. Also, it looks like it took them 13 days of inspecting, cleaning, testing and repairing activities to finally solve the problem. Again, good luck; you'll find the problem soon.
Here is where I am at today.
I have replaced the the cam sensor and DIS unit first. runs the same. Starts smooth then 20-30 minutes it bucks and tach goes to zero.
I then replaced the crank sensor ,same old issue. Ran in my driveway for 30 minutes then started same old stuff. (it starts the same after every thing I have done.)
The next time I ran it I tugged ,shook the wiring in the front of the engine and that had no effect.
The reason I ordered a replacement PCM/ECM is the fact I am out of good ideas.
The first one I got made the car beltch smoke and would not run with out me pumping the gas pedal.
I then plugged the original unit in and it ran smooth like always at start up.
One point worth making is after a couple of the bucking ,tach to zero episodes the tach recovered and the engine started running smooth and I continued driving for more than 30 minutes with no issues.
I hope to have a replacement ecm/pcm next week some time.
I plan to get some brighter lights and magnafying glass to further inspect the wiring.
Thank you all for your ideas !
I have replaced the the cam sensor and DIS unit first. runs the same. Starts smooth then 20-30 minutes it bucks and tach goes to zero.
I then replaced the crank sensor ,same old issue. Ran in my driveway for 30 minutes then started same old stuff. (it starts the same after every thing I have done.)
The next time I ran it I tugged ,shook the wiring in the front of the engine and that had no effect.
The reason I ordered a replacement PCM/ECM is the fact I am out of good ideas.
The first one I got made the car beltch smoke and would not run with out me pumping the gas pedal.
I then plugged the original unit in and it ran smooth like always at start up.
One point worth making is after a couple of the bucking ,tach to zero episodes the tach recovered and the engine started running smooth and I continued driving for more than 30 minutes with no issues.
I hope to have a replacement ecm/pcm next week some time.
I plan to get some brighter lights and magnafying glass to further inspect the wiring.
Thank you all for your ideas !
Yes, I replaced the DIS a third time a few weeks ago. Cleaned both surfaces and coated both part and mount with new paste
David Neibert
SCCoA Admin
The stator is another name for the Cam Position Sensor. See attached link from google search.
E9SZ12A112A Motorcraft | Auto Value
David Neibert
SCCoA Admin
Aftermarket DIS or a Motorcraft unit ? Asking because my car won't even run on an aftermarket DIS. I've tried 2 from Orielly's auto parts and car would barely stay running. Installed an old used spare and it fired right up and ran smooth.
Aftermarket ... I did buy another pre owned DIS Iwill try that one this weekend
Update:
Tested then replaced the battery, still the same old stuff 20 minutes of driving and it bucks and coughs . Then if I can keep it running within many seconds the tach recovers and starts running smoothly again.
In a conversation with a former ford mechanic he reccomended replacing the engine coolant temp sensor so I plan to grab one today and see if I can get it installed this week.
Tested then replaced the battery, still the same old stuff 20 minutes of driving and it bucks and coughs . Then if I can keep it running within many seconds the tach recovers and starts running smoothly again.
In a conversation with a former ford mechanic he reccomended replacing the engine coolant temp sensor so I plan to grab one today and see if I can get it installed this week.
I have no idea if it's remotely related or not but I just fought a long battle with a cam sensor issue and figured I'd share.
Have you hooked up a oscilloscope to the cam sensor? I found that in my case the signal was out of spec, almost twice the peak to peak voltage, along with 'noise' between the signal pulses. Turns out the cam sensor spacing was the cause? Once I spaced the sensor out approximately 2mm, the signal was in spec and the 'noise' was still there but with far less amplitude. All was finally well once again.
Have you hooked up a oscilloscope to the cam sensor? I found that in my case the signal was out of spec, almost twice the peak to peak voltage, along with 'noise' between the signal pulses. Turns out the cam sensor spacing was the cause? Once I spaced the sensor out approximately 2mm, the signal was in spec and the 'noise' was still there but with far less amplitude. All was finally well once again.
Update :
After talking to a friend and former Ford dealer mechanic ,he suggested I look at the engine coolant temp sensor. As he predicted it was all corroded. I swapped it out with a new ford sender and have driven the car two days in a row to work and back with no issues.
Not quite ready to calim victory but hopefull this is the end of it.
Thank you to all that took the time to reach out !
Blue skies !
Dave
After talking to a friend and former Ford dealer mechanic ,he suggested I look at the engine coolant temp sensor. As he predicted it was all corroded. I swapped it out with a new ford sender and have driven the car two days in a row to work and back with no issues.
Not quite ready to calim victory but hopefull this is the end of it.
Thank you to all that took the time to reach out !
Blue skies !
Dave
I tried several ECU's and we are not sure what is unique about this car,but it would only run with the original.
The Ebay seller I bought them from was great.
You could have diagnosed this very easily with a moates quarterhorse to live stream the actual ecu inputs.
If something goes out of wack its value turns red so its pretty straight forward. For the ECT to make the tach drop off it had to be killing the engine by reading full cold and flooding her out.
I have 2 issues similar to this over the years.
The first was my black 90 I got from Jersey back in 08. The coil pack was weak and made the car buck violently and cut out under throttle.
The other was 91 titanium that would just spew black smoke out the exhaust randomly after driving. That was a faulty ignition switch.
If something goes out of wack its value turns red so its pretty straight forward. For the ECT to make the tach drop off it had to be killing the engine by reading full cold and flooding her out.
I have 2 issues similar to this over the years.
The first was my black 90 I got from Jersey back in 08. The coil pack was weak and made the car buck violently and cut out under throttle.
The other was 91 titanium that would just spew black smoke out the exhaust randomly after driving. That was a faulty ignition switch.