99 f250 superduty - Ford Forums - Mustang Forum, Ford Trucks, Ford Focus and Ford Cars

codycalvert · 08-12-2009, 13:48

i have a 99 superduty, that misses between the speeds of 40-55. It is not throwing a code, i have scanned several times. I put a fuel pressure gauge on and it seems to fluctuate when it misses. i have also installed a new fuel pressure regulator and it did not fix the problem.. Anyone out there had this problem before? if so give me a shout and let me know.. thanks

**360ci** · 08-14-2009, 12:48

Are you in overdrive when this happens? If so, drive at that speed in 3rd gear (rpms will be in the 2500rpm range; approx), and see if the miss still occurs. If the problem goes away, then you could rule out a fuel problem. If it's still there, it could be a number of things. A tune up can always help, especially if it's been 40K since the last one. Be sure that the plugs are gaped correctly and if the truck has original wires, replace them. Without a code it's always hard to diagnose. If it's electrical, then it'll be even harder.

acalvert · 08-18-2009, 11:33

I have the same truck...Sell it if you can!!!!!! The missing is caused by a coil pack gone bad. I keep a supply of them at all times. This engine is notorious for litterally blowing spark plugs out of the head. I have had 2 blow out and strip the threads. Heli coils were put in (BIG MISTAKE, use threaded inserts). Now I have a thread stripped plug that won't come out and I'm facing upto 3k in repairs to pull and probably replace the head. Shame on you Ford for putting alum heads and not using steel inserts for the plugs....

Back to your problem.....it usually takes mine a few weeks before it throws a code. Go ahead and get a coil pack or two from Oreilly's or Ford, NOT Autozone. But be prepared, this is just the beginning!!!!

codycalvert · 08-23-2009, 19:05

have any good coil packs that u would like to get rid of?

73power · 09-21-2009, 21:37

I take it this is a 5.4L. Had one in a 97 which is the first year they were made. Junk!! Loved my 4.2L over this pos 5.4L. Ford made a VERY faulty design on the coil packs. Mine seemed to go when I hit water - puddle extreme rain on the road etc. Mostly #'s 3 and 4. Ended up going to Tires Plus quite a lot.. at least every two months. Roughly was about $120. Can buy them cheaper from NAPA or whereever and change them out yourself, make sure to put a new plug is as well, the ones in the back are a *itch and I would pay someone else to replace those if I was you.. more hassel than its worth!