2000 F-150 130K miles 4.6 always ran like a top - till a few days ago it started skipping, bucking etc. No codes or check engine light. Had original plugs, finally bit the bullet yesterday - new platinum plugs, new springs & boots.

Ran almost OK for about 5 minutes - then, it's baaaaack.

Any ideas? I'm almost positive the coils are OK, because it seems to idle ok - wifes expedition was forever blowing coils - got CEL & the thing would shake & rumble with 1 bad coil in it.

Possibly the computer?? Anyone know how to check the thing if I pull it out?

Pulled it out this morning. No bent pins, no burnt smell. Appears OK, but that doesn't mean anything.

Appreciate any suggestions. Right now the truck is basicly undriveable. You might reach your destination with minimal skipping, or it could skip sooo bad right out of the driveway & keep stalling.

Where can we pick up these things at a reasonable price?

Thanks a-lot.

Billy D

 

It is highly unlikely that anything is wrong with your PCM.

You just need to do some deeper diagnostic work. The first tool of choice will be a scanner capable of reading your misfire counts. Read your misfire counts and you'll likely find at least one cylinder is elevated.

Bad COPs or other misfire causes don't always set the MIL right away.

Steve

 

I agree that it probably isn't the PCM. They are not well known for failure. There is no way to test the computer; you have to test everything else and if that's all good you have a shot of whiskey, buy a new one and hope for the best.

 

I agree with the guys, highly unlikely it's the PCM. Check all the boots, snags in the wiring, loose connections. Get yourself a code reader capable of running in real time.

 

*** Follow-Up ***

Ended up taking truck to the dealer. Told him I replaced the plugs, boots & springs and still misses badly. Guages doing some crazy things, etc. but not getting any check engine lights or anything.

Ended up being the number 1 and number 4 coil (going bad, but not a complete failure, yet) and . . they said I needed a computer re-flash.

What's a reflash? Is it like reloading the software? Did it loose its memory or something?

$500 dollars later, it's running great again. Also, a month or so I had the tranny (actually every fluid in the truck) fluid replaced, and didn't really notice a big difference. Now, after the reflash, It shifts smoother than my wife's new Pathfinder.

Question. If I bought one of those programmers, like a superchip type of thing, could I have used that to re-flash the computer?? I'm not sure how thay work , but I thought someone said you buy it, plug it in and it "removes" the vehicle's original program and then you install the towing or performance program etc. If I had say, the towing prog. in there, and it started running rough, could I have removed the towing program & re-installed the original??

Would that have been the same thing as re-flashing??

Thanks,

Billy D

 

Updated calibration. Usually due to revise emissions operations, sometimes "bug" fixes or to improve operation of the system, especially transmission operation. We can only guess since the dealer probably didn't tell you the exact reason for the reflash nor do we know what calibration was installed.

The programmers only save the current program and data before installing the modified tables and software. Since users generally don't have access to the downloadable dealer flashes, it wouldn't have helped you.

Your original symptom was likely due to the weak COPs causing a misfire. Very common.

Steve