Killing my PIP

[67686977]

Driving the bronco Saturday, pulled up to a stop light, and noticed the afr was reading really lean. Then it would show really rich. I knew what it was by the way the tach and afr was acting. This is my third distributor, two previous we're auto zones and the current is a Mallory. I got a code 14 in all the cases. PIP circuit failure. My question is.. Is it a wiring issue? Heat related? TFI or the actual part inside the distributor. In all the cases it has happened within 200 miles of driving. Hoping someone will point me in the right direction to start diagnosing the problem. Thanks

 

[Viperwolf1]

I doubt it's a heat issue or it would be happening in a lot more Broncos also. I would test the PIP wire between the TFI and ECM connector (pin 56). Should have less than 0.2 ohms of resistance from end to end and more than 70K ohms between it and ECM pins 20, 16 and 36 with the TFI connector off.

Have you replaced the TFI with these failures? PIP signal goes through the TFI to get to the computer.

 

[67686977]

Not on the first two, autozone warranties the entire distributor. Going to pick up another TFI and check the readings on my wires. Just curious as to why I am going thru so many this quick.

 

[DirtDonk]

What about having a manual computer hooked up like an automatic, or vice versa? Would that do anything like this? Normally the result is a burned trace in the computer itself, rather than a sacrificed TFI, but it was just something that popped into my head.

How does it rev up to higher rpms? This wouldn't have anything to do with that one wire on the TFI having a voltage signal all the time that's only supposed to get one under start would it?
I'm thinking not, but figured I'd ask anyway.

Good luck.

Paul