92 F150 Jerking/Studdering Misfire at 45-60 MPH
 

Ive got a 1992 F150 with the 5.0 302 and within the past 2 weeks I've been dealing with lots of misfires between 45-60 MPH. As soon as the truck shifts into OD and I go to apply the throttle it will buck back and forth like a 15 year old learning to drive stick for the first time. Now I've done some homework on this issue and I know it is not my tranny as that was my first frightful thought. My problem seems to be within the ignition somewhere. I have read that for many, it is the coils packs in their trucks, but these trucks being 1998 and newer, mines a 1992. So hears the question, does my truck even have coils packs?? I have no idea what coil packs are so that's why I'm asking. I have replaced my spark plugs within the past 3k (Autolite 25 platinum's) miles so I wouldn't think they would be the cause of this problem. I bought the truck 4k miles ago and supposedly the wires were changed then as they do look newer than an OEM set. Where should I begin to check and run tests to find the problem cylinder(s)? My CEL is not on so I do not believe any codes are being thrown. Any help on this would be greatly appreciated!:thumbsup:

I would also like to add that the truck has lost a lot of low end power, it barely climbs hills anymore. And periodically whenever I come to a stop and put the truck in park, it will have a high idle. But doesn't happen every time.

Our trucks have a single coil, notcoil packs, and it is really easy to change...I think on the v8 s is right on the top of the motor not sure though. If it's the original coil I would change it and give it a tune up ( plugs, wires, brass cap and rotor, and new coil). This should help my coil went bad and the truck was bucking while going down the road like you described.

Edit I didn't realize the newer plugs and wires, in that case just change the cap and rotor and coil.

Thanks for the reply and info! Done a little more searching around the internet and found the ignition coil you are talking about on our trucks. Even a "replacement" video on youtube and it is right on top of the motor like you described. Should be a very simple fix IF this is the problem like I'm hoping. Gonna make a trip to Autozone tomorrow and buy a new ignition coil and ill get back to you on it. But good to hear that you had the same problem. I believe my truck also had a new cap and rotor when the wires were replaced by the previous owner so the coil should be the problem. Thanks again!

92 F150 Jerking/Studdering Misfire at 45-60 MPH
 

My $0.02:
Is your truck equipped with a tach?
If so when the truck "misfires between 45-60 MPH"
does the tach bounce off zero - like you turned the key off?
From my experience these coils are not that prone to failure...
I would look more at cap and rotor as well as module and/or mag P/U inside the distributor.

As for the internmittant high idle I would check the upper plenum bolts and make sure they are tourqued and then look at the IAC.

Regards,
Toddsss, Benton, AR

if youre unsure of how new the cap and rotor are you can take the cap off and look at the contacts if they are corroded then you need to replace both the cap and the rotor. the coils on these trucks rarely fail you could also check the ground at the coil if its not grounded properly it could give you troubles like youre describing. the high idle could be your throttle positioning sensor going bad but that usually throws a code

Okay I've replaced my cap and rotor button along with my ignition coil and the shudder is still there along with the loss of power. Also did a trans and differential fluid swap to full synthetic, everything looked good. What else could be wrong? I've checked all my wires and even had a second opinion on their condition by a friend. Everything looked good. My CEL came on last night while going down the interstate but it went away after about 3 seconds. It would only come on after a real bad shudder. At this point I'm beginning to think its a sensor somewhere but I don't know where to look. I removed the elbow going from the airbox to the ram induction a while back in order to try and get better mpg's (it actually helped). Could this be causing my problem? I did it about a month and a half ago and now this shudder is happening.

Sorry but as bad as I wish it did, my truck does not have a tach so I wouldn't know. But the truck seems to be doing that just from the feel of it. It will be at a controlled speed and then just fall out as if it lost all motor power, then it will immediately pick itself back up and slam back in gear and continue on down the road like nothing happened.

Just because the light doesn't come on or stay on doesn't mean there aren't codes, so pull codes.

Would an Autozone scanner be able to read any codes? Even if the CEL isn't on?
Just wondering as im about 5 minutes from an Autozone here in town. Would be easy to stop bye and check for codes.