paulie710@aol.com

I Recently bought an 06 F150 5.4 140k For the most part the truck idles and runs fine but under a load or going up the Hill it breaks Up no misfire codes Or anything just AP0446 which is an Evap code Has anyone else had this problem

dukedkt442

The breaking up ARE the misfires. Plugs/boots. Not sure about the evap code, probably unrelated.

650NutKase

Plugged cats?

paulie710@aol.com

Not getting any misfire codes

dukedkt442

You usually won't.

ShirBlackspots

Most videos I watched suggests this behavior is from the spark plugs needing replaced. I was having a small amount of bucking under light acceleration, and after I changed the plugs, it didn't happen again. Its been suggested (in these forums) to replace the plugs every 60,000 miles, so you needed to have it done 20,000 miles ago.

AlleninNM

The misfire count required to set off a code is significantly higher than the number of misfires it takes to be noticeable. If you have a code reader capable of reading mode6 data, you will likely see a misfire count. If your reader shows pending codes, it may also show a misfire code without a check engine light coming on. As indicated by others, time for a change of plugs and boots.

River1

Consider trying a new gas cap.

TheOldRaker

My truck is doing a similar thing, without throwing evap codes though. But this caught my attention, because I can't seem to fill my tank without turning the gas hose handle upside down, if I try to fill it holding the handle in a normal fashion, it keeps stopping. (Like the overfill safety stop at the pump handle. Not trying to hijack a thread, just thought it might be relative.

Wwebster12

Watch this video. I was chasing a ghost until I found this. Bought this scanner from parts store and found my problem. Cyl 3 and 7 were missing but not throwing codes. At idle it was the noticable miss and under load slightly uphill in overdrive.