I have a Ford F-150 4.6 V8. The RPMs has started to surge up and down while driving at a constant speed. If I take it out of overdrive it doesn't surge. It starts fine and no missing. Changed the fuel filter today. No change. I have a K& N air filter. I also cleaned it with their kit. No change.
Check fuel pressure and scan for codes. Clean throttle plate on both sides with choke cleaner as well as iac hold if you have one.
November, 18, 2012 AT 11:22 PM
I took the truck to the ford dealer. They hooked it up and no codes came up. They couldn't find the problem.
I changed out the fuel pump module above the spare tire. This did not help. I drove it a couple miles and the engine died when I pulled into a parking lot. It started right up and I drove it home. It died when I pulled into the driveway. It will restart, but while idling, the rpms will raise and drop by 100-200 rpms. It used to ony surge when I was driving in overdrive at a constant spead.
I haven't tryed cleaning the throttle plate yet, but plan on it over the holidays.
November, 18, 2012 AT 11:47 PM
K& n filters can cause problems if they are oied to much so make its not