2001 f150 Supercrew, 4.6L

Let me first say I've been a lurker on this site for years, without the information I've gleaned here, my pre-runner project would've never been able to happen. I've come across a problem that I've not been able to find an answer to after multiple searches.

My #8 injector is dumping fuel into the cylinder, so much fuel that it's fouling the plug, and dripping out of the header! I've had the injectors out and benched, all good. After pouring through the factory service manuals, I've deemed that my problem is linked to a grounding issue either in the injector wiring harness, or in the computer itself. I've disconnected the computer harness and isolated the ground wire to the #8 cylinder, did an ohm check to see if it was grounding anywhere, and it checked out good. I'm led to believe there is a ground short in the computer somewhere that is keeping the #8 injector wide open. Anyone ever hear of that?

My only hitch is, when I reconnected the connector to the computer after doing an ohm check on the injector ground wire, the injector did actually work properly for a short time (10-15 minutes), until the injector started dumping fuel again and fouling out the cylinder. Can the computer problem be "intermittent"? Did I "reset" the computer when I disconnected the connector, and it was "happy" then for a short while? Or did I simply move the connector in a way that the potentially grounded injector wire was "fixed" when I did my ohm check? Then, after reconnecting it to the computer and running for awhile, the wire became grounded again..

If it is the computer, my next question is going to be, how do I go about ensuring compatibility of a wrecking yard computer replacement? Is it as simple as any computer out of a 2001 4.6L f150? What are the rules for choosing a replacement? Are there any compatibilities that I can take advantage of to broaden my possibilities of finding a match?

thanks in advance
-doug

 

If you replace the ECM, regardless of what you get you have to have a dealer reprogram it for your VIN and PATS before installation.

 

well since i'm on a posting spree, even though you pulled the injector and it bench tested good, swap it with another injector and see if that clears anything up for you. see if the injector that you swap into position 8 still floods out. look down inside where the injector installs check to make sure that their isn't anything that could lodge the injector open. then proceed to drink lots of beer and contemplate what to do next if you put a new computer in you'll have to have a stealership reprogram the hole thing again and I think its kinda costly $$. Best of luck.

 

I did swap the injector into a different cylinder, and was REALLY hoping it was that simple. Unfortunately I wasn't able to duplicate the problem elsewhere, #8 cylinder still dumping fuel.

I'm running out of beer!

So, if I get a wrecking yard computer even if it's out of the same vehicle, year, body, engine, etc, the stealership (that's a good one!) has to flash it or reprogram it?

 

Yes.

 

What do I need to look for in a replacement computer? Is exact model year important? What numbers on the computer are relevant in my search?

FYI regarding PATS: I have a custom tune in my programmer that deletes the PATS, as I no longer am using the factory column (ignition switch).

 

I'm hoping to get some clarification on what I need to be concerned with in choosing a computer that will be compatible with my truck, anyone?

 

^ You may need to clarify that with a dealer... Have tried just having them re-flash it?

 

I've gotten a few from NAPA and all I've had to do is give them a description of the truck and the PCMs have come to me already flashed. Might try a NAPA in your area.

 

I'll try NAPA, thanks!