I have an '05 F150 5.4L with 110k miles on it. Bought it used about 2-3 years ago and have had on-going ignition system problems. The current problem is a significant shudder/shake/vibration that occurs when driving 50mph+ (easy to reproduce around 65-70) on the freeway, when starting up a minor, but noticeable incline. This is an incline that doesn't require much additional throttle, and this trouble occurs with cruise control on and off. the truck starts shuddering pretty rough during the incline. However, if I release the accelerator (and go up incline with slightly lower speed) or give lots of gas on accelerator the shudder usually stops. The shudder always clears after the incline when returning to flat road and just cruising.

This occurred on a recent trip a few times and I pulled the following codes (in order):

P0356 (once) : Ignition Coil F (6) Primary/Secondary Circuit Malfunction
P0302 (recurring): misfire on cylinder 2

I have since purchased and replaced the coil on #2. This did not resolve the problem. I have replaced coil on #6 in the last year...

Because I saw a suggestion somewhere on the net around this problem while searching, that this could be related to OD, I tried disabling OD and enabled OD on an incline today to test after replacing COP on #2 and it seemed to resolve the issue to turn OD off. Not sure if related...?

Other observation: Cab of truck often smells of gas just after starting the truck. Mentioned this to the shop, but they didn't find anything obvious.

Appreciate any suggestions!

Short history of codes and work that has been done:

Sometime in early 2011: Ford service dept did this work.
First failure was coil bad on #7. Tech swapped 7 & 8 to verify the problem followed the coil. Then when the problem DID follow the coil, he replaced #8 with new.

05/2011 MacKenzie Ford changed all plugs

12/2011 - swapped out COP on #7.

02/2012 - P0306 - Now, COP #6 is reported as bad.

November/December 2012
P2104 P Throttle Actuator Control (TAC) - Forced Idle
P2112 P TAC Stuck Close
P2111 TAC Stuck Open

I did throttle body clean - removed it and used TB cleaner. replaced...

Late December 2012 - while driving on freeway at speeds 50+, but easily reproduced around 60 after starting up a slight incline. symptom is heavy shudder/shake. Possibly resolved by turning OD off.
P0356 (once) : Ignition Coil F (6) Primary/Secondary Circuit Malfunction
P0302 (recurring): misfire on cylinder 2

Appreciate any help and suggestions...
-Kelly

 

i would check the fuel system, like the FPDM, it rusts out alot, fuel filter, fuel injectors especially #7 i hear its prone to goin bad.
you might have a lean or very rich condition considering the gas smell

 

Thanks for the suggestion. I finally took it into the shop after swapping out coils didn't resolve the problem. They found a plug that was completely missing the tip - no spark = miss, right?
However, the gas smell is still present in the cab. And while I haven't observed the pronounced shudder, i'm not 100% convinced the problem is fully resolved. Hard to know if I'm just being extra-sensitive to any vibrations now or if some of the very subtle ones are a real issue.

 

aha, i had that exact problem
i just changed out my plugs cuz i had a rough idle all the time and one of the plugs had an electrode burned right off. id post pics but i dont do photobucket.
my rough idle was cured but i still have a bogdown/runs rough issue when its cold.
like you i agree theres still an issue to be fixed
i suspect a lean condition from bad injector or FPDM or fuel filter