what causes your car to run lean?

 

clogged injectors, clogged fuel pump... im sure theres more.

 

FPR?

 

Well if your fuel pressure regulator isn't regulating right ( not enough flow ) I'd imagine it would run lean.

 

of course that too.

 

bad 02's(the ecu gets an incorrect signal and compensates for a false signal), vaccuum leak(unmetered air), exhaust leak... would cause the o2s to send out a rich condition but they would meter lean. clogged fuel filter, too small of injectors, one of your sensors sending a false or no report to the ECU and cusing a lean A/F mixture.....thats about all I remember besides the ones that were listed

 

not enough fuel






























I know I'm a smartass

junk in your fuel tank, not big enough injectors, a bad fuel pump
are a couple I can think of

 

the ECT and the ACT sensors being out of range can cause this also.

 

i agree.