hey guys new to to forum. i have a 99 f150 5.4L 4x4 that just popped up with the p1151 lean on bank 2 code. I just had the transmission rebuilt about 2 weeks ago and two days later the code popped up. there seem to be no drivability issues, but if im driving about 50 mph and let off the gas and kind of ease back on it it misses until i stomp it.

Heres what i did so far:
changed the o2 sensor
cleaned MAF
hear no vaccuum leaks
checked to make sure injectors are ticking.
i had brought it back to the transmission shop and they said it could be the pcm or the injectors but they didnt touch anything to make it do that (Of course).

what im going to do next:
change the iac gasket. (i replaced the iac about 2 days before the transmission went out and reused the gasket. I know rookie move ).
spark plugs.
check vacuum on the egr
fuel pressure check.

im pretty stumped on this one guys so any help would be great. im going to try to do the iac gasket today so well see what happens.

 

Occasionally a misfire will set a lean code. If the cylinder doesn't fire, it doesn't use up all the oxygen. The unused oxygen then leaves via the exhaust port and passes over the O2 sensor. When the sensor sees oxygen, it's voltage drops and the PCM in turn can set a code for a lean condition as a result. If you suspect a cylinder is misfiring-I'd address it first.

 

thanks i appreciate the reply. i may change the plugs this weekend along with the coil boots. its weird because it doesnt misfire all the time just around 50 mph maybe a couple of the plugs are fouling. changing plugs on these trucks takes a while i kind of been avoiding the task

 

misfire around 50 is a classic sign of a shorting coil

 

would that cause the lean code? i just changed the spark plugs and wires about 20 minutes ago so im still waiting to see if the code comes back. i did scrape some corrosion off of the coils when i took them off.

 

i totally misunderstood what udderbrudder said. i just realized that my previous post makes me look like an idiot. a coil would make sense. about two months ago i had a problem with them on that bank, the rear two got wet. ill just have to wait it out untill it crap on me i guess? Im not getting the miss anymore but it seems like when i go to accelerate its not getting any gas. sort of bogging down.

 

so just a quick update. i finally caved in and went in to the local ford dealer. They said the PCM was bad, it wouldnt connect to their computer. i guess that could be my problem. anyone heard of this?