Ford F150 - I-6 miss at speed but not at idle or during accelleration

Greetings all! Bought a 95 F150 in December and love it. (shame about the cheapo OEM oil pans, but...)

Anyway, I'm having a problem I can't get a handle on. Rolling down the highway, I have an intermittant miss at speed. Sometimes it's really noticeable, other times it's not as bad. Idles like a top, and no problems during accelleration. No stumble on decel, either.

I tried the obvious...plugs, wires, injector cleaner. Nada. Pretty frustrating since I've fooled around with classic cars and motorcycles for years, just none with any kind of computers and such. Guess I'm a dinosaur, huh?

Any ideas will be greatly appreciated. I'll check back in a few days. Thanks a million!

did you pop the cap off the distributor and make sure the contacts are good? check the coil too...timing...thats all i can think of, might have a shitty dist. Cap and it gets moisture or something, id check that out, and since you are a 'dinosaur' haha i dont think you will have a problem finding it.

You need to add more info about your truck to your profile: engine, trans, 2/4WD, cab/bed configuration, etc. It might be U-joints, d'shaft slip splines, rear pinion nut, diff, wheel bearings, or even tie rod ends.

Hey, ya caught me still online! Thanks for the ideas~already checked the cap (seemed electrical to me) but haven't yet swapped out the coil. Maybe even a bad injector? I'm just hoping for a "common" issue that'll be easy to fix without really tearing into things, since I already have one car somewhat apart in the garage. I confess I never considered anything in the driveline. Have to give that a look, too.

I added a vehicle description to my profile but am not sure if it went through, so what I have is this:

1995 F150, I*6, AOD, 2wd, 3.55 limited slip, reg cab, LB, shocking green paint, an oil pan about rusted out, and only two specks of rust on the bed wheel wells.

So thanks again, and I'll keep checking back if anyone else has anything to add. When we figure this out (and we will) I'll post the results.

~Randy

One quick and easy thing to check, how's the battery/charging system?

Dirt,

I see the electrical boogeyman has visited your garage, too!

One of my toy cars is a 74 VW Bug stroker...yep, punched out to 2284 cc's. We're guessing about 130 hp. One of the most fun cars I've ever owned by far. Last fall it started acting up, missing, not idling right, etc., and after I went over everything it turned out the generator wasn't putting out enough current to handle the hotter spark at higher rpm's. Two evenings of screwing around, and then one hour to swap out the gen. Been fine since.

Nope, charging system seems fine. It does this at all constant speeds. I'm willing to consider all ideas (even though I'm convinced it's electrical or sensor-related) which is why this afternoon I fired it up in the driveway and ran the throttle up and down without moving the truck, and an old dwell meter/tach hooked up. Same deal, and that seems to have ruled out drivetrain issues.

Are the cam position sensors known to go bad on these?

Cam Position Sensor is a good thought...

Yup, as you say, as a dinosaur hanging around these younger guys experience tells me to think of the simplest of things first too....

Your Bug sounds like a cool project. I have been itching to put together a sand rail (street legal use only) but just haven't found the time or money, or a donor car for that matter....

Sounds good to you, sounds good to me...CPS'll be my next step. Turned cold up here (about an hour north of Pittsburgh: Steelers rock!) over the last day or two and since this is a spare vehicle I'm going to wait a bit before I tear into it. Plus, I already have the dash and door panels out of my 49 Ford Tudor so I don't want to rip into anything heavy just yet. My hobby's out of hand already (I even blew the cash on a 4 post hoist) so I gotta be organized. I'll keep you posted, and again many thanks.

Good luck with your future veedub! Mine's been a blast, but I have to thin the herd and I'm putting it up for sale this spring. Drop me a line if you want and I can send you a few pics for your entertainment. My email address is the same name I use here, and I use AOL.

Later..........Randy

There is no CMP (CaM Position sensor) on any 4.9L. Only '96s have a CPS (Crank Position Sensor), but it's called a "misfire sensor" & they don't go bad.

Is yours a 49-states (MAP), or a CA-emissions (MAF) truck? The MAF is attached to the air filter cover outlet, so it's easy to tell.



What's the actual gap on each of your spark plugs? Compare it to the spec on your emissions sticker. I burned a set to 0.110 before mine started missing on accelleration.



While you have them all out, do a compression test.