Bluegrass, my 2002 F150 (5.4, 183kmi) is jerking under light load in top gear and RPMs are below 1500. For example, when maintaining cruise spd 40-50mph, if I encounter a hill or lightly apply the gas, there is a hard, irregular jerk. It is not a regular washboard feeling. I have had a couple coil packs go out on me, and it feels very much the same, except when a coil pack goes, it doesn't care which gear I'm in. This jerking only happens in 4th gear/overdrive. I have read a lot and it seems a tossup between torque converter or torque converter clutch and coil packs. Problem is I can't find any reference to coil pack only misfiring in 4th gear/OD and at low RPMs under light acceleration.
My best hope is for this to be a fluid issue. I plan to drop the pan and drain the TC and add some Dr. Tranny or similar to see if this solves the (pressure?) problem.
your wisdom is needed good sir, i have an engine problem that seems to be recurrent and you are the only person that comes to mind that would have the knowledge i require to get the right parts and tools for the proper repair.
Bluegrass, thanks for sharing your wisdom. My 97 Dodge Ram is doing the same hard jerk that you speak of at 45-50 mph. However, I think the Dodge only has a single ignition coil. Does it still make sense for that to be the problem? Thanks for any advice.
HI! I saw your post on the cars that were Bucking between 40 & 60 MPH & your information was invaluable. Seeing you really know your stuff I just wanted to run something by you. I have a 2008 Ford Edge SEL AWD that just went in for it's 90K mile tune up; new filters, new oil, new spark plugs & wires. After this tune up I had the occasional bucking like people are reporting. Could it be coincidence that a coil might not be right after this or could it be a faulty wire or plug? It wasn't doing this before they changed these. I have had it in a few times and can't get them to see anything on their computer or feel it when they had it and I have 2 road trips to go on from NY to upstate this weekend and NY to NC next weekend and I just want to get this fixed. SO if I could tell them what to do it might really help! your reasoning behind the coils is great I just found it weird this wasn't happening before they changes spark plugs & wires so I just wanted to check with you! thanks!
I was reading a post that you had commented on about a shudder at 40mph due to faulty coil pack issues. I am having the same shutter issue around 40mph with mine and realize it is probably a coil problem. This may be a stupid question but my battery is really weak and I am trying to delay getting a new one. I read somewhere in here about low voltage at the coil cause it to miss read could a weak battery possibly be causing this problem? I never noticed the problem before my battery was weak.
Hi Bluegrass, Hope I am not imposing but I saw one of your trans. answers and thought you might be able to help me. Whenever I shift from park to reverse i get a delay and an idle surge of approx. 200-300. rpm. If it is cold it is a little more. Then it kind of clunks into gear. It does the same going to drive but the rpm increase is less. Is this trans or engine. It is a 4R70W. F-150 4x4 5.4L. When driving all operations seem normal. Pulls strong through all gears, shifts up & down normally. Just had fluid & filter replaced.
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