Hello all. Here's a little information about my truck. It's a 2000 F-150. Two wheel drive. 5.2 Liter V8. About 133,000 miles on it currently.
Here is the problem I have been having with it recently. Right around 45-50 mph, my truck starts to jerk or studder as I attempt to accelerate gently. It has not been too bad, but it has been prevalent for the past few months. Yesterday, after an 8 hour drive on highways, when I got back onto a regular road, the truck would jerk/studder around 45 mph and it was so bad that I could not drive past 45 mph.
It does not always happen when I drive, but now it is occurring more frequently. I want to bring it into the shop, but want to hear what you guys have to say about this problem first. Thanks!
You may never get a code from the issue.
The problem is one or more faulty coils that are "not" hard faults so will not set a code you can see with a reader or see a light from.
Only other way is to use a good mid level "Scanner" to trap the fault or have the coils stress tested by a dealer to find any with low output.
Fyi to all: If you have any tendency to shudder under light loads at anythime, there is a high likleyhood of a low output coil.
Reason: Under low speed and light throttle on and off, the EGR system operation causes very lean air/fuel ratios that requires higher coil voltage to fire.
If one coil has low output, that cylinder will missfire until a shiftdown, higher throttle or any action causes the air/fuel ratio to become richer allowing the coil to fire again.
Then the shudder goes away until the next time.
This temporary condition does not set a code.
Get a scanner that can read any "pending" codes. These do not always trigger the CEL.
My 97 F150 had the exact sysmptoms you describe. Under light load at approx 40-45 the transmission went to bucking and got worse over time.
Only with the scanner was I able to get to the root cause. A cyl 3 misfire. Turned out to be the plug wire. 5$ fix.
Wait, so you were experiencing what felt like the transmission bucking or slamming around and it turned out to be the coils? I am experiencing the exact samething, happens usually when under load or cruising. It gets so bad that i have to wait for the rpms to stop dancing on the guage before I can continue. Happened 5 times today alone trying to get to work.
If I have a 4.6L with the 2 coil packs, could I be experiencing the problem with misfiring?