avmech

2002 f150 4.6L 140,000mi, automatic

My truck has had a hesitation/shudder during acceleration off and on for the past few weeks. It does not do it if accelerate in park, only in gear. Had a tranny shop look at it and they said tranny worked great, that it had a misfire or something. I put in fuel injector cleaner today and pulled a few plugs. The plugs were Autolite so they are not original and they were in good shape, I didnt pull the rear ones, if youve changed them you know why. Have voltage to all coils with key in "on". Checked resistance on two of the coil packs and they were slightly higher than my chilton says they should be, causing my prob, I dont know. Manual also said to check for voltage at camshaft sensor and I have no voltage at the plug, did the check on the sensor itself and it showed a very small change in AC volts, not sure how much it should swing on a bench check.

Any suggestions appreciated, what i work on has tricycle gear and two wings and the ol ford has neither!

Thanks

avmech

anyone have any ideas? I think its prolly a COP, but how do you know which one if it only misses under a load?

maxidyne

I just went thru this on my 01 f150 4.6l. I had a buddy do a powerstand at 1200rpms while I unplugged cop's. unfortunatly my miss was so intermittant I was unable to figure out which one it was. I picked up a set of cops from a junk yard for 50 bucks and swapped em all. Miss went away. Currantly swapping my original cops back in 1 at a time till I find the one/ones that are bad. Hope this helps.

jensen41455

I have an 02 with a 5.4 in it and it is doing the same thing. The shudder is so bad that it feels like the engine is just going to jump through the hood. It only does it under a load as well. It was running fine until I decided to put new brakes on it and change the oil. I had some corrosion on my positive battery post so I disconnected it to clean it. I have a gryphon tuner and its not giving me any codes. A buddy of mine thought maybe a fuel pump but that doesn't seem right. Everything else I've had a bad fuel pump on has always had a hard time starting. Any ideas? How should I check for a bad coil?

westtnfx4

You don't have to have your truck "under load" to test your cop's....just at idle unplug each coil one at a time....when you feel/hear a change in the engine idle you know it's good. If you unplug one and there is NO change in the idle/running you know you have found the bad cop....simple.

avmech

Thanks, Ill give that a try!

avmech

It finally kicked on the CEL......Camshaft sensor. Replaced it and its back to running like the 4.6 it is!

MellowJ

Same shudder in my 98. I went to Autozone and they put a code analyzer on my truck. I think it was cylinder #8 that was misfiring. I've read through enough forums and decided to change out the coil ($52) instead of trying to change out the spark plug - the one closest to the firewall. Problem solved!


Update:

Shudder showed up again with the Spring rains so I changed out the other coil pack. My truck ran good for a few days but still wasn't quite the same. I still had a misfire. Went down to Ford and bought some performance spark plug wires and my truck has been running perfectly ever since. Looks like one of the wires was grounding out on the block.

JorgeRod54

im kinda vague on the lingo, but im running into the same issue. my truck is idling at 500 rpms, seems like im not gettin enough fuel or or somethin, but u get on the pedal and itll go. when im around 35 or so, it gives a good hesitation, like there's a bad mixture. im running a k&n fip kit and ive seen that some people run lean. but idk where to start. ive already changed my fuel filter, running super unleaded, oil changed, MAF and air filter cleaned.

what is a COP and where is it located?

westtnfx4

A cop is a "coil over plug" ....each one of your plugs (on a 5.4 and on newer 4.6's) has a coil that connects directly to your spark plugs. 8 plugs 8 coils. Follow the advise I gave on how to check the above.