Tumbleweed Posted April 28, 2009 Report Share Posted April 28, 2009 I've got a 1998 f-150 4 x 4 that's always run fine. Lately when I get up around 60-70 mph it starts to run really rough and when I let up on the gas it rumbles and shakes until it gets back down around 55 or so. Also when you step on it the engine goes but it is not smooth and feels like it's missing some power. Any ideas? Thanks. Link to comment Share on other sites More sharing options...
Jay in the Bay Posted April 28, 2009 Report Share Posted April 28, 2009 Sounds like something is misfiring. Take out one of the spark plugs and see if tyhe thrweads are coverwed with oil. If that is the case, you may need to replace the valve cover gasket. If not, maybe the plugs and wires need to be replaced Link to comment Share on other sites More sharing options...
JimW Posted April 28, 2009 Report Share Posted April 28, 2009 Try a new fuel filter. "I have ... put a lump of ice into an equal quantity of water ... if a little sea salt be added to the water we shall produce a fluid sensibly colder than the ice was in the beginning, which has appeared a curious and puzzling thing to those unacquainted with the general fact."- Joseph Black Link to comment Share on other sites More sharing options...
canyondiver Posted April 29, 2009 Report Share Posted April 29, 2009 Any vacuum leaks? You can check for them by spraying brake cleaner on the vac line connections and listening for a rise in idle. Mind you, this is after checking the lines carefully by eye!! Proud to be a NERB and I have the shirts to prove it!! Link to comment Share on other sites More sharing options...
ted527 Posted April 29, 2009 Report Share Posted April 29, 2009 not sure what year ford went to the coil on plug set up but that may be your problem. i have a 2001 f-150 that had the same symptoms, ended up being bad coils on cylinders 1 and 8. had to take it to a ford dealer that could hook up to observe real-time conditions as the problem would not throw a code into the obd system. Link to comment Share on other sites More sharing options...
Brigbassman Posted April 29, 2009 Report Share Posted April 29, 2009 Get a code reader or go to an auto parts store that does it for you. It will tell you if there is a misfire and which cylinder. Probably a coil, I have a 98 f150 and it had a bad one with same type symptoms but was running rough even at idle. Link to comment Share on other sites More sharing options...
Tumbleweed Posted April 29, 2009 Author Report Share Posted April 29, 2009 Thanks for the replies. I did have the all the plugs and wires replaced about 2 years ago because it was doing something similar but at that time it was running really rough at idle and was causing the check engine light to come on. Link to comment Share on other sites More sharing options...
speedracer Posted April 29, 2009 Report Share Posted April 29, 2009 Theres at least 100 things it could be. Go to your mechanic and ask him to hook it up to an analyzer. This way you won't waste time fixing something that ain't broke. You're getting sleepy. ....very sleepy..... Link to comment Share on other sites More sharing options...
ted527 Posted April 29, 2009 Report Share Posted April 29, 2009 with 2 coils going bad my truck would idle as smooth as the day i got it. only under certain conditions would it run rough and it had no codes stored in the computer that my mechanic could read. he reccomended i take it to ford and they had a different system that could see the misfires. Link to comment Share on other sites More sharing options...
Backbeach Jake Posted April 30, 2009 Report Share Posted April 30, 2009 coil wire. Corroded at distrubuter cap. Link to comment Share on other sites More sharing options...
Charleston Posted April 30, 2009 Report Share Posted April 30, 2009 One of the plug wires is shorting to the engine. Or broken. I am old but I'm slow. Link to comment Share on other sites More sharing options...
fishaholic18 Posted May 1, 2009 Report Share Posted May 1, 2009 One of the plug wires is shorting to the engine. Or broken. Most likely.... Link to comment Share on other sites More sharing options...
demonfish Posted May 1, 2009 Report Share Posted May 1, 2009 My wife's 1997 Expidetion had the exact problem. Ford uses a coil for each plug. One coil was bad. $200 to replace it. Link to comment Share on other sites More sharing options...
Chunkah Posted May 1, 2009 Report Share Posted May 1, 2009 My wife's 1997 Expidetion had the exact problem. Ford uses a coil for each plug. One coil was bad. $200 to replace it. Same thing happened to my 1999 F-150 only mine would ride rough around 50 mph. It turned out to be one of those coils....mine was covered under warranty. Link to comment Share on other sites More sharing options...
rwalter7 Posted May 1, 2009 Report Share Posted May 1, 2009 Typically an ignition problem is amplified when under load like acceleration but as bizarre as this sounds I had a similar problem with my Ranger. Granted they are different vehicles but it turned out to be the transmission being low on fluid. CT Link to comment Share on other sites More sharing options...
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