troyandtammi

Going uphill my truck shutters like a misfire. No cel code is set. If I back off the gas pedal it goes away. Going to start by changing the plugs. The original plugs have already been changed out. Do I need to be aware of any problems with changing out these plugs or am I good to go being there not the original factory plugs.

techrep

iTrader: (1)

If they were installed properly with anti seize you should have no problems..how many miles do they have on them ??...have you checked the condition of your FPDM located under your spare tire corroded to the frame rail..??

18_F-150_XLT_Screw

iTrader: (1)

Have you checked to make sure the plugs are still torqued? They will back out sometimes and can cause gas smell and misfire.

mjlater

I've never heard the FPDM could cause a misfire. Are you sure?

techrep

iTrader: (1)

Oh yea... he stated it shutters like a mis-fire and going up hill would be under a load..

mjlater

Mine does the same exact thing also. When in overdrive and i roll into the throttle really lightly it will misfire as well. These are signs of FPDM gone bad? I always thought it was a plug or COP. Let me know.

techrep

iTrader: (1)

no... I'm not saying that... I'm saying I have heard of the FPDM causing what he described..if your CEL is flashing or setting a DTC it very well could be plugs or a COP...that's what you should check first...even a clogged CAT will cause a mis-fire..

troyandtammi

I changed out the FPDM almost two years ago as a preventative maintainance item. It had two spots that had started to corrode. Ordered SP-515's from Rockauto. They should be here by next weekend. The current plugs have about 48,000 on them. It only happens on a steep hill, otherwise it runs perfect. Does not set off a code. Everyone's advice is appreciated!

Mad Irishman

Keeping an eye on this thread as I am having the same problem. I have new plugs, boots and a Lisle tool sitting in the garage. Just looking for some time to install them. Hopefully tomorrow.

dipschnit

I had COP causing the same issues only when in overdrive and no code showing. Ive also had the FPDM cause issues as well but when it was the FPDM it had more symptoms and wouldnt go away. Id say its a COP.