11rangerZ520

Have a 2011 5.0 f150 with 100k miles. Been at the dealership over a week with multiple calls to ford hotline. Runs rough at idle and slightly misfires at higher speeds under load such as going up a hill. Has p0300, p0305, p0307 codes(all misfire codes). Before this it would “ping” on lower octane fuel. Dealership tried plugs, coils, purge valve, crank sensor, maf sensor and throttle body and they couldn’t fix. Any ideas?

SALEEN961

iTrader: (1)

That's ridiculous that the dealer has just been throwing parts at your truck instead of tasking the time to diagnose the problem and fix it the first time. Cylinders 5 and 7 are both on bank 2, I would start by checking the exhaust back pressure on this bank and running a leak-down test on cylinders 5 and 7. It may also be advisable to run a leak-down test on all the other cylinders as well, it's not terribly common, but sometimes the codes do indicate the wrong cylinders. I had a Nissan with a melted and cracked coil on cylinder 3 throw a misfire code for cylinder 2. Thinking along those lines I have to ask, when the dealership replaced the plugs and coils, was that just on cylinders 5 and 7, or were all eight plugs and coils replaced?

Stu Cazzo

Dealerships no longer know how to diagnose problems. Its been a thorn with me now for some time.
If your truck doesn't throw a code...then according to the dealer, theres nothing wrong with it.

If it does throw a code, then the "tech" cross references the code to the respective fix instructions.
Thats how vehicles are serviced and repaired.

These "techs" are nothing more than slightly trained monkeys!

Theres a real lapse in any form or ability to troubleshoot or attempt at diagnosing a problem and furthermore "techs" don't get their info from you (usually) they get it from the service advisor.

11rangerZ520

Update! They preformed leak down test, compression check, tested vaccum, and back pressure test. All came out fine. They said possibly the crank itself but they aren’t really sure.

ozracin

crank position sensor is probably out of wack. get a SCT x4 tuner, do a crank relearn , it's under special function below clear codes.before you do the relearn make sure you clear the codes and follow the instructions. When I bought my used f150 mine did the same thing. And it fixed it

11rangerZ520

Thanks for the info. However they put a crank sensor in it, shouldn’t that have solved that issue or no?

ozracin

I would think so, but it’s worth a shot

MustangAndy

Ain't that the truth. Two Ford dealers couldn't find the clunk in my 2004 F250's front end. My buddy at Firestone found it in 10 mins and had it fixed 20 later. Diagnosis: Front swaybar link bushings. Found by using the shop's alignment rack (suspension loaded) after a standard four arm post lift revealed nothing (suspension unloaded).


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bradtx

The dealership can perform a cylinder drop test to find a flakey coil or fi. Can take some time to find more than one misfire, but I've been successful.

Brad

FLXLT

They should have performed the relearn process for you. It is necessary when replacing the crank sensor. Would throw a code if the relearn procedure wasn't completed.