We have a 2003 F150 V-8 with 63,000 miles. We got some bad gas a couple weeks ago and it ran awful. We used a fuel addittive to dry the water and then used a couple containers of the Lucas fuel additive. We had the system checked (for the service engine soon light) and was told it was a mis-fire on # 4 & 5, so the plugs were replaced and so was the fuel filter.

The engine still has a miss after first cranking, at idle and usually at slow speeds. We do not have the $$ to take it to the dealer and have them start throwing parts on it.

What can we do/check on our own to get it running right? Someone told me the coil packs may be bad and it was a "known" issue with the F150, but considering he thought the truck was a 1998 and that bad gas really did not hurt the engine or cause problems, I am not too sure he knew what he was talking about.

Thanks for any suggestions/info.

 

The best thing to do, would be to go to Autozone, or Orielly's or similar place and get the OBDII codes checked. Depending on where you are , in most states they will do it for free. But before you buy parts, post the exact code numbers here for advice.
Welcome

 

Thanks Tumba. We did go to Advanced Auto and they just said mis-fire on # 4 & 5 but I will go back and get the exact codes.

Thanks!

 

Ok we have the codes - P034 #4 cylinder misfire & P035 #5 cylinder misfire. The plugs still looked good but we changed them anyway and we changed the fuel filter.

Any suggestions? Thanks.

 

Did you try trading the cops with different cylinders?
Was there any water or rusty looking deposits in the cop boots?
But I would try changing the cops with two other cylinders that are easy to get to, and see if the miss follows.

 

Did you replace the plugs with OEM Motor Craft?

 

We used Motorcraft plugs. We will try to swap and see what happens. Thanks.

 

Correction, the DTC codes are P0304 and P0305, sorry.