Good morning all - I finally received my code scanner for an issue that's been driving me up the wall. KOEO self-test pass then a continuous 212 / "Loss of ignition diagnostic monitor signal/SPOUT circuit grounded." I find these systems super aggravating and ended up carb swapping one years ago -- I am very committed to NOT doing that here but gee I am frustrated. Doesn't help I am supposed to be driving a whole group of people to the mountains in 4 days and the vehicle is letting me down.

Vehicle:
1994 Club Wagon Chateau - 351 / E4OD / 4.10s - ~120k miles. Overall in good shape, POs perhaps a bit behind on fixing little leaks and such but not tampered with. All the harnesses look untouched. PO added an aftermarket head unit & light bars lol. GVWR a tad below what I have found for the e350 and well above the e250 so I think it's the bigger version of the Chateau but not the HD.

THE ISSUE:
I have had an intermittent misfire / loss of ignition. Especially notable when cold. At idle you can hear little audible hiccups like it's misfiring. Under load it can be particularly notable -- shocks to the driveline as it goes from working hard to 'nada' & back again. Previous owner threw a lot of parts at it - not idea how much diagnostic was done overall.

PO replaced: TFI (black / Transpo brand), TPS, MAP, coil, distributor (with cap n rotor), maybe wires, in-tank fuel pump, who knows what else. Autozone quality parts at best.
I have replaced: Copper plugs w/ Motorcraft wires (I went back and separated them based on the service bulletin), new Motorcraft coil. Oil change and some tidying up. I popped open the PCM and replaced the 3 typical troublesome capacitors (no visible leakage evident) for good measure. None of the work I have done has had effects on the issue. I've also thoroughly cleaned the ground from battery to chassis at drive front rad support. PCM connector pins 20/40/60 all have good ground. Read at 0ohm to 0.1ohm - my meter doesn't go any more sensitive to get more decimal points on that.

So with the 212 code -- I jumped in just now and after pulling the battery ohm'd out the TFI to PCM pink wire # 929 / 18. No short to ground. No excessive resistance. I had test probes connected to the TFI and PCM connectors and wiggled the harness - a little float in readings but nothing out of range. Pulled the spout - it's clean and the circuit passed the testing from those points outward too.

So... What the heck??? I'm gonna try and see if I can manually trace circuits to see if I should have a black or gray TFI I guess. I hate to throw parts at issues but other than full replacement of the PCM or the TFI with a Motorcraft I'm low on ideas with this one. Thanks in advance - I appreciate the experience / wisdom anyone has to offer!

 

I traced the white w/ pink tracer circuit 648 from the TFI connector to pin 4 of the PCM -- so that confirms the vehicle matches my 1994 CCD diagrams & I believe confirms the black is the correct TFI. The 'push start' gray TFIs have a start voltage signal to that pin from what I have read.

I went ahead and ordered (nothing local - even with the 45% markup the local shops have IF in stock) a Motorcraft DY1077 black remote module to replace the existing black Transpo. Years ago I got a Mopar voltage regulator from Transpo where the truck wasn't staying stable. Didn't solve my issue so I thought 'hey could be one bad one' and got another with the same result... after a lot more effort on grounding and other checks, I finally bought a Mopar brand and *poof* the issue was fixed. I've come to dislike Transpo from that experience.

Fingers crossed!

 

Sad but true - the fairly new Transpo unit was bad. As soon as I got the Motorcraft in place she hasn't hiccup'd since. After about 450 miles in the mountains this weekend my confidence that she is fixed is pretty high.

Never put too much trust in new parts - especially aftermarket. =P