Help the old guy with his Electrical ECM issues

[dmkberger]

Hey guys, I'm the guy who put a '95 Mark VIII engine and trans into my 1957 Ranchero, now it's a '57 Lincoln RanchCustom... I'm having dificulties because of swapping in '98 intake, coil over plugs and I'm not sure what's causing my issues.
If I unplug the Mass Air Flow Sensor the car starts right up and runs really good, when I plug it in it backfires and will not stay running. I'm using the OEM wiring harness from the Mark VIII and have all of the stuff wired as close as I can get it so the power windows work fine, The A/C works normally, The Power Locks work and the Fuel Pump runs as it should.
But the wiring diagram of the Ignition switch has two Gray and Yellow wires circuit 687 that are making me crazy. theres a couple of others that are causing me issues as well. I have a 1994 Mark VIII wiring manual FPS-12136-94F and a Factory Service Manual for the '95 Mark VIII as well as the same Factory wiring Manuals for the '98 Mark VIII. I come from a shop in the Chicago area, I was shop foreman in a Cadillac, Rolls Royce and Bentley Dealership for years. I finally switched to Ford products and have come a long way towards doing what I used to do at that dealership, but I'm still not a pro with Ford. HELP ME PLEASE

 

[driller]

Hey guys, I'm the guy who put a '95 Mark VIII engine and trans into my 1957 Ranchero, now it's a '57 Lincoln RanchCustom... I'm having dificulties because of swapping in '98 intake, coil over plugs and I'm not sure what's causing my issues.
...HELP ME PLEASE

From reading your post, I'm not sure I understand everything with your setup.

What PCM (computer) and wiring harness are you using?

What MAF sensor are you using?

You swapped over to the " '98 intake, coil over plugs"... which specific intake? The '98 Mark VIII intake manifold or a '98 Cobra intake manifold?

Was the setup running before the intake swap and COP swap?

When you swapped over to the coil on plugs, how exactly did you modify the wiring? Did you buy a 'plug-and-play' kit or modify the wiring yourself?

What brand coil on plugs are you using? What spark plugs are you using?

A lot of questions, I know, but there are important specifics relative for each answer.

As far as Ignition switch circuit 687 (GY/Y), there are two pins (A2 and A3) which should be hot in the run position. What is the specific problem/question?

 

[dmkberger]

The ECM I am using is the OEM '95 Mark VIII which is a rebuilt ECM if you want to call it that. The '98 intake and coil over plug set up is from a Factory Mark VIII. I did not have the engine running with the OEM '95 ECM, The Throttle Body was too low and WAY to close to the '57 Ranchero firewall. I bought a cross over kit for the coil on plugs wiring which was plug and play, the coils are OEM and the Plugs are brand new and are the ones listed for that motor. I used MotorCraft Plugs and EVERYTHING I use is FORD/ LINCOLN. I'm not sure what's happening other than putting those on with those on the Ignition Switch for the '57 Ford the Fuel pump relay and another relay under the dash will not shut off when I turn the ignition switch off. The engine stops but the two relays stay alive and make a buzzing noise until I disconnect them and they are quiet till I restart the engine. And the Mass Air Flow Sensor will not work and causes the engine to backfire and shut down. I have to get back out there but I can't for a couple of days. I appreciate you taking the time to respond and hope you'll be willing to help as this goes on. I want to DRIVE THIS CAR!!!!

 

[driller]

I'm not sure what's happening other than putting those on with those on the Ignition Switch for the '57 Ford the Fuel pump relay and another relay under the dash will not shut off when I turn the ignition switch off. The engine stops but the two relays stay alive and make a buzzing noise until I disconnect them and they are quiet till I restart the engine.

Okay, so apparently the engine will start and run, so let's skip over the intake/COP swap and examine the ignition switch wiring and/or possibly the MAF sensor.

You're using the Ranchero ignition switch? I recall the old school Ford ignition switches were rather basic. Just a battery terminal, starter solenoid power and run/accessory circuit. I remember jumping across the ignition switch harness plug using a simple Y section of wiring. Basically just putting battery power to the run/accessory circuit and temporarily jumping across the starter solenoid circuit to crank the engine.

The ignition switch and wiring for the Mark VIII run/accessory circuits are significantly more complicated. The ignition switch has multiple battery feeds and segregated circuits. My question is how did you integrate the Mark VIII circuits to the Ranchero ignition switch? I ask this because it sounds as though you have a back feed issue between circuits which causes some circuits to be energized despite the ignition being turned off?

If you refer to the factory manual for the '95 Mark VIII you will find component tests for the ignition switch and associated circuits. It sounds like you have the majority of it sorted out, we just need to drill down to what the specific issue may be. Most of the diagnostics are simple enough and involve testing at the power distribution box under the hood.

It may not sound like much help, but the symptoms of the fuel pump and other circuits not turning off with the ignition switch off is where the answer is in my opinion. Ignore the MAF, intake swap and COP swap for now. Search for the circuit or circuits that have power after the ignition has been switched off.

One last thought, do you have a breakout box for the ECC-IV PCM? I have found them to be particularly useful for circuit diagnostics.

 

[dmkberger]

I wired the '57 Ignition switch using the wiring diagram from the '95 Mark and I guess it's too much for that switch to handle... I will go out today and look at the componant tests for the ignition and associated componants. I do have the Factory I think it's called the EVTM Manual as well. and will go over the tests for the ignition componants. I do not have a break out box for the ECC-IV PCM. Might be a good idea to do that but.... That would take a LOT of work to take the dash out and get to the wiring and the ECM... I might consider changing over the ignition switch to the OEM Ignition switch somehow.... Lemme look into that. Thank you so VERY much driller, El Presidente. Vaya Con Dios mi Amigo

 

[driller]

Here is the pin-out for the ignition switch and the corresponding circuits and circuit functions:



These were from screenshots from the '96 service manual, but I believe it should be the same for a '95.

Note the separate battery inputs (B1, B2, B3...) and circuit outputs (A1, A2, A3...). The EVTM will show greater detail as to the circuits for each.

 

[billcu]

You say when you unplug the Mass Air Flow Sensor the car starts right up and runs really good. Does it stay running when the car warms up? I had a bad power wire to my MAF once, the car only ran when I let the car cool down and left the MAF connector unplugged, it ran long enough to get me home. Maybe check the power to the MAF?

 

[dmkberger]

I'm going to pick up an ignition switch and wiring harness this coming Tuesday or Wednesday. There is a VERY nice Junk Yard that has several Mark VIII's and the owner is a friend who will sell me one for almost nothing. I have the ignition switch wiring shot you've done the screenshot of and I've been following wire by wire to see what the heck I might have done wrong. I found one wire that goes from the Mass Air Flow Sensor to the unit that mounts in front of the Radiator that controls cooling fans and other stuff, I've had two strokes and my memory fails me on the term that Ford uses for that unit and it then goes from that unit to a 16 wire connector that then goes to the ECM and other stuff. But the wire I had hooked to that wire I thought went to the CCRM, (I just looked it up) and found that I hooked it to another wire I was sure it went to and was REALLY wrong. So, I corrected that mess and will see if it makes the Difference that I hope it will, I'll let you know later today. But I'm gonna get the correct ignition switch and will figure out how to hook it to the ignition switch I have, But I might have to switch out the steering column for a column with the Key in it linked to the correct ignition switch.... This is kinda how this build has been since I started it 13 years ago... Too many times I've been called away to fix this car or that car or repair big stuff on grandma's house and so on. I hope to have it running and driveable before the heat hits this May or June.... We'll see. Thanks again!

 

[driller]

It sounds like you may have found the issue with the MAF sensor? Let's hope so.

As far as the ignition switch, I hope you can figure out how to keep the Ranchero switch.