No luck with "crank but no start checklist"

[Hozer 88GTConv]

Gents,
The stang died at idle 6 weeks ago in the driveway. No previous symptoms except a sticky starter solenoid.

I performed the items on the "crank but no start checklist"
1. When I removed the connector from the starter solenoid, ignition on, and jumpered the screw to the bolt, I got a crank but no spark from the coil plug to a good ground.
2. New coil, new solenoid, no spark. Checked 12volts at the coil wires. Checked all fusible links at the solenoid, the eec-iv relay by the computer and the fuel pump relay, all good with 12v where it should be.
3. New TFI module.
4. Plenty of fuel pressure, and I smell and hear it too.
5. Battery is great, sat it on the charger to ensure plenty of juice.

What next? The PIP module in the distro??...I can't think of much more.
No codes, the STO light stays illuminated during KOEO tests.
Some of the injectors buzz too with the ignition on.
Thanks in advance.

 

[HISSIN50]

...............2. New coil, new solenoid, no spark. Checked 12volts at the coil wires. Checked all fusible links at the solenoid, the eec-iv relay by the computer and the fuel pump relay, all good with 12v where it should be...............

When you checked for '12 volts at the coil wires' did you note the test light flashing when placed across the two wires? The ground pulse to the coil comes from the TFI module. So the test light should flash like a pulsar.

A noid light can be helpful in seeing of the injectors are energizing properly.

I'm sure Jrichker and others will be of more assistance.

Good luck.

 

[Hozer 88GTConv]

Thanks, Hissin.
I followed the checklist, meaning I checked for 12 volts at the ignition coil red/lght green wire.

With the key turned on, I should see a "pulse" on my noid light?
"did you note the test light flashing when placed across the two wires"
Not sure what you mean here, but I appreciate your help. Do I need to pierce both wires simultaneously? Or just observe one "pulsing"

Thanks, again.

 

[Hozer 88GTConv]

I just tested the coil wires again. No pulsing at all, just constant 12vdc with the key on.

 

[HISSIN50]

Ok, you got it. Those were two separate items I was talking about. The coil test was putting one leg of the test light on each Coil electrical connector wire. While cranking, the test light would flash on and off pretty fast.

The noid light and injector test was separate. I find it helpful to see if injectors are getting 12 volts and a ground pulse (confirmed with a noid light) because it can rule out a PIP.

It seems to me that if the coil test failed (on the ground pulse side; you had 12 volts to the coil with they key-on), but you have injector pulsing, that suggests a TFI issue or an issue in the wiring from the TFI to the coil.

For a grey TFI module (what you likely have in your '88), I'd see if terminal #2 on the TFI has a ground pulse coming out of it. As I recall, this is where the ground pulse for the coil comes from. This would test the wiring in between the TFI and coil.

Good luck.

 

[jrichker]

When the check list doesn't work, it is usually a lack of understanding of exactly how things work or a critical test step was skipped.

Here's the short version of how it works:
Key on engine cranking:
The PIP sensor inside the distributor provides the signal to fire the injectors and TFI module on computer command. No PIP signal, then no injector pulse nor trigger signal to the TFI. The Noid light placed on any easily accessed injector confirms PIP signal operation.

The computer can fail and the ignition will still fire. The computer uses the PIP signal to create the timing for spark advance. It calculates the spark advance and sends the advance signal to the TFI module via the SPOUT circuit. If the computer does fail, you get spark, but no timing advance. The timing stays at whatever initial timing was set with the timing light and manual adjustment.

PIP signal present as evidenced by a flashing Noid light, then the problem is a failed TFI module, ignition coil, no 12 volts to the red/green wire on the ignition coil, no 12 volts on the red/blue wire on the TFI module or other wiring problem.

 

[Hozer 88GTConv]

Thanks Jrichker and Hissin.

There is no pulsing present on the noid at either the coil or injector number 5while cranking.

No 12volts to red/blue on the TFI either.

PIP sensor.

Thanks, again.

 

[fordman54935]

I would check the voltage on the throttle position sensor. If its dead, the car will never start, regardless of fuel/air/spark. It's happened to me - It did give me an error code as well. Good Luck