Random cutting out, no EEC codes??

[Laredo]

Will a sporadic TFI module set a DTC in EEC 4? I have a random cutting out / stalling occasionally a few seconds after a hot restart, usually light/med throttle. Fuel pressure never falters (checked w/manual gauge) while it's stumbling. KOEO test - 11, CM - 11, KOER - 25 (knock sensor). Seems like ignition but my TFI is less than a year old.

[Patrick]

I had one do that which turned out to be old plug wires." Less than a year old TFI" is meaningless if the PIP did not get replaced at the same time. The PIP may be the culprit. When my last dizzy died, codes led me to "No Tach Signal" reply from the scanner. I forgot which code number that was. I replaced the whole dizzy rather than just the easy part. The rebuilt dizzy comes with TFI, PIP, bushings, and a new gear as well. It was $95 before core replacement rebate.

[Laredo]

" Less than a year old TFI" is meaningless if the PIP did not get replaced at the same time. The PIP may be the culprit. .

Nope - not the Pickup sensor. Replaced module, PIP, and plug wires. Still cutting out. Seems like something going on in ignition primary - now that it's getting worse and more frequent, I can see the tach snapping down to 0 as its cutting out. Got too dark outside to continue searching tonight (and too late after a long work week.) Tomorrow I'll throw a volt meter on the coil + and - and try it again.

[MikeFleming]

Things to verify: TFI wiring harness, coil & associated harness, ignition switch and wiring.

[brsvo]

Sounds like a coil to me.

[in2fords]

same thing happened to me after I replaced the distributor just couple days ago. turned out to be the blue wire on the TFI connector, it was broken in the plastic at the sealed connector. It would die everytime I tried to turn the distributer while doing the timing thinking that was why it was running rough. The wire looked still connected but it stretched when pulled.
check wiring, start it up and wiggle the wires.

[Laredo]

Had a few minutes tonight to check a few more things out. Steady battery voltage to coil +, but while cutting out voltage on the ground side of the coil fluctuates - same as the tach. Also, timing light flash cuts out as stumble / misfires happens. Confirmed steady battery power to TFI, also jumpered DG/Y wire from TFI to coil, still cutting out (part throttle, light load) http://s216.photobucket.com/user/WALaredo/media/MVI_2726_zps7a7716a3.mp4.html (http://s216.photobucket.com/user/WALaredo/media/MVI_2726_zps7a7716a3.mp4.htmlhttp://s216.photobucket.com/user/WALaredo/media/MVI_2729_zps153b8ed6.mp4.html) http://s216.photobucket.com/user/WALaredo/media/MVI_2726_zps7a7716a3.mp4.html

[Laredo]

Sounds like a coil to me. Nope, tried that...

[MikeFleming]

How does the wiring to/from the TFI harness stub look? Those wires have a tendency to have the wiring insulation fall off, with predicable intermittent results due to engine vibrations.

[Laredo]

How does the wiring to/from the TFI harness stub look? Those wires have a tendency to have the wiring insulation fall off, with predicable intermittent results due to engine vibrations. Thanks Mike. They actually look really good, and I "wiggle tested" the heck out of them with no effect. But just to confirm I jumped battery power to the "run" TFI terminal and a also jumper overlay wire from TFI coil output directly to the coil ground side. No change. Also measured the voltage directly at the TFI coil output terminal, it does the exact same jumping/fluctuating as at the coil. And when measuring across the two wire ends of this circuit while the misfire happens, I get 0 voltage drop. Pulled out the SPOUT, no change. So...I'm thinking this must be a TFI input issue. According to the EVTM, the engine will run without the IDM signal back to the ECM but will have "limp in" base timing. I don't have that problem, timing advances normally (until it stumbles, then the spark just shuts off, as indicated by the timing light flash). Next I was thinking of confirming a good ECM ground and then overlaying the PIP wire from ECM to TFI. Looking at the wiring diagram, pins 40 and 60 ground at G122, but location is listed as "frame" (??). Anyone know where this is?

[MikeFleming]

Looking at the wiring diagram, pins 40 and 60 ground at G122, but location is listed as "frame" (??). Anyone know where this is? If you have ever removed an EEC in a Fox, you're noticed a small gauge black wire with a round loop lug on it just forward of the bottom of the metal opening where the EEC slips into. And one of the 7mm Hex-head (iirc) green bolts that holds that black wire lug to the chassis. THAT will be the droids you are looking for.

Personally I would change the PIP and TFI first - at least pull the dist cap and rotor and inspect the PIP wiring and molding goop.

But it never hurts to verify wiring also. It's good practice for old cars.

[Laredo]

Nope - not the Pickup sensor. Replaced module, PIP, and plug wires. Still cutting out.


Personally I would change the PIP and TFI first - at least pull the dist cap and rotor and inspect the PIP wiring and molding goop.

Already replaced both w/brand new, first knee jerk reaction replacement...and just cuz' they were 27 yrs old, - no change. Also swapped out coil and plugged in a different ECM that I had sittin' on a shelf (easy swap and didn't cost me anything). Not much left other than wiring / connections. Is there perhaps some other ECM input signal that would cause spark to shut down?

[svopony]

did anyone suggest the column switch........?

Bar

[Laredo]

did anyone suggest the column switch........?

Bar
Yes, and I have one of those on the shelf too. Haven't tried that yet because all of my battery "run" voltages are steady everywhere I check, even when it's acting up.

[MikeFleming]

Have you checked for steady power to the EEC and fuel pump(s)? The EEC relay is in the far, upper right behind the dash. A test light should give quick results.

[Laredo]

Have you checked for steady power to the EEC and fuel pump(s)? The EEC relay is in the far, upper right behind the dash. A test light should give quick results.
No, not directly. But I figured all that was OK since fuel pressure is steady/normal when it's cutting out. Haven't had a chance to get back to it for a few days. It's been miserably hot/humid, temps in the mid 80s. Can't work in those conditions. S'posed to cool off tomorrow.

[MikeFleming]

Fuel pump(s) would need to be off for a second or more at that low a power level to affect fuel pressure. If I understand your desciption, the "interruptions" are partial second events?

[Laredo]

Checked all the ground wires, dizzy ground, EEC relay, overlayed PIP wire from ECM to TFI - all OK, still cuts out. Even though the PIP and TFI are brand new, grabbed the whole distributor out of my 100K Turbo Coupe, dropped it in the SVO - runs perfect now. WTF!!! :confused:. Now I'm just pissed. What the hell is left in the dizzy other than the PIP and TFI? All the wires came new with the new PIP.

[MikeFleming]

Get six candles and a bag of salt ...

Is the vane thingie in the dist loose??

[dagenham]

It's been miserably hot/humid, temps in the mid 80s. Can't work in those conditions. S'posed to cool off tomorrow.

I'll trade your mid 80's temps for the "feels like 104 with the humidity":cool:

[MikeFleming]

115 here today. Supposed to rain some later in the day. Then it'll drop to maybe 90-100, with 80% humidity. Good time to be driving with the AC on.

[Desert Patina]

If it makes you feel better, it did this to me even with a new distributor. But it's pain enough getting someone to machine out the cog on the shaft.

[brsvo]

Is it just me or are the parts coming out of part houses now days bad a high percentage of the time? You got a brand new TFI/PIP and it wasn't good? I bought a brand new IAC this spring and it was bad returned it and the replacement didn't work one more time and then I got my money back. 3 tries and 3 bad units. Ironicly all I wanted was one that looked cleaner as my old one still worked!

[stockman1]

Is it just me or are the parts coming out of part houses now days bad a high percentage of the time? You got a brand new TFI/PIP and it wasn't good? I bought a brand new IAC this spring and it was bad returned it and the replacement didn't work one more time and then I got my money back. 3 tries and 3 bad units. Ironicly all I wanted was one that looked cleaner as my old one still worked!the quality has certainly gone down hill