Hey guys, from what I read I seem to be having an issue that many others have, yet I never seem to see definitive answers. My 07xlt just started having a terrible rough idle after driving enough to get the motor warm. 99% of the time it happens its after decelerating and coming to an idle, mainly pulling into parking spots, stop signs, red lights, ect.. Once at idle the roughness will stay even when shifted to park or neutral, seemingly the only immediate fix is taching it up to around 3k then the idle will smooth out. During the month I've been fighting this I have had horrendous fuel economy and only been thrown a camshaft position sensor code, followed by the same code 2 weeks after changing both sensors. Any questions or input would be greatly appreciated!

 

Post the exact codes and tell us which engine you have. How many miles on the truck and on the spark plugs?

 

Sorry my man, its a 07 xlt with the 3v 5.4. ~220k miles and roughly 40k on the plugs at the moment. The code it gave me was the same both time and it was p0345 bank 2. It threw that code the first day it started, i changed both position sensors, saw no improvement but didnt get a check engine light for a couple weeks. once I did get another check engine light and it was the same code so it kind of scared me into thinking it was a timing/phaser issue.

 

I also forgot to add something that may be important. Im a very competent parts changer, just not the best diagnostician. But my landlord is the one who had the fancy bosch scanner to check everything out for me and he told me that everything looked good aside from the scanner showing my fuel consumption was at 4% at idle. Im assuming that just means the amount of fuel being used at idle is as if my pedal was depressed 4%? Which may be an indicator as to whats wrong, also explains my terrible fuel economy.

 

I would not rule out phaser/timing issues.