ok so yeah as per the title, the truck is messed up, ok so it has a rough almost eratic idle, changed the pipes caused they were blown out, thats what started it, goin down interstate, rolled out of the throttle, egr was locked up from carbon so i guess pressure built up and when i let out, BOOM!! then i got to a stoplight and it died, got home barely and me and my dad have scratched his head bald to try to figure it out, but me and him dont know much about the 5.0 EFI engine on an 86 F-150, weird thing is, its sounds ok i guess when you rev it but when it idles its like running rich or something, the only bright side to this is i got some glasspacks, and i cant even tell if they sound good cause i cant drive ol' red, so yeah ANY help would be appreciated,

p.s Manifold Absolute pressure sensor?

Anthony

 

Put a code reader on it and see what you get.

 

code reader said it was somethin to do with the ignition system, that cant be right?

 

Yes it could.

Could be fuel pressure regulator, ignition control module, etc, etc. Trust the code reader. What specifically did it indicate was wrong?

 

Also pull the vac line off the FPR and make sure it's dry. They rupture the diaphragms and puke fuel through the vac line into the motor...

 

do believe it said ignition circuit system malfunction and (FPR?)

 

Anyone smell a TFI module? The FPR has no actual sensor on it, and there is no fuel rail pressure sensor on it either. So you wont get any FPR codes. BUT you will know if it is bad because all you have to do is pull the vacuum line off of it. If it is wet, then you have a leaky FPR, if not, then its good.

 

it said profile ignition sensor circuit malfunction

 

PIP sensor? Thats the sensor in the dizzy right? Sounds like you have some dizzy problems! I would suspect the pickup coil in the dizzy along with the ignition module. If you have enough cash I would buy them both (even if the ignition module is not bad) because the ignition module WILL go out, and you could either save the new one for when the old one fails, or you could put the new one in and save the old one as a backup. Also be sure to get the tool to remove the module. It takes a special socket. The wall on a regular socket is too thick to fit into the holes on the module

I believe (but maybe not) that the TFI module reads the PIP sensor signal, or the signal travels through the TFI module one way or another. So I guess I would just work on the TFI for now, and if that doesnt do anything, then worry about the pip sensor. Dont feel bad just trying a TFI module, because it will be the worst time when it goes out. Mine went out at about 1:00 am on my way home from my GF's house. She lives 20 miles out in the country, and it went out about 8 blocks from my house in town. I wound up walking the rest of the way home, waking up in the morning, getting the TFI module, putting it in on the street, and driving it home.

Dang it anyway huh?

It was odd because If I floored the truck it would go fine until about 2k, then it would miss and backfire. I though I had other problems, but as soon as I put in the new TFI, bingo, it runs great now!

Also before blindly throwing parts around, be sure to check all wires, harnesses, connectors, etc. You can save alot of money that way!

 

thanks!ill try that

 

well my dad already changed the tfi but the main problem is that its running rich which is causeing a rough eratic idle

 

I had an 86 that acted like that ,the timing chain had alot of slack in it.

 

just had it replaced, it wont start right now but its turning over super fast and i think one of us hit the dizzy so it probably screwed it up

 

I Found changing out the IAC helped my 86 5.0 EFI alot (I wasan't getting any codes on the old one either)

 

I would clean my old Iac before I bought a new one.