: Cold Start Problem ?

04-05-11, 04:55 PM
I have a cold start problem at below 32 F. Car starts but runs really rough and the idle jumps all over up and down and it can just die. A code reader says lean on both banks. It has new pugs and wires and that didn't cure the problem but it was time anyway . The car has 125,000 miles on it. Any thoughts on the source? Thanks . Jeff

04-05-11, 06:29 PM
If it were mine I would start by changing the fuel filter and testing the fuel pressure at the fuel rail. It could be pre-cat O2 sensors, but I wouldn't think both sides would go out at the same time.

04-05-11, 08:59 PM
Has the car been sitting for an extened period of time?
Could be a bad batch of gasoline.
Did you notice this condition after a 'fill-up'?

04-05-11, 11:22 PM
I should have added that I changed the fuel filter at the same time as the plugs and wires. It happened about a year ago when it sat for a couple of days at Copper Mtn. ski area but now its all the time when it gets cold. When the temp warms up it starts normally and the check engine light goes off. I drive it everyday sun,rain, or snow Jeff

04-06-11, 07:13 AM
See attached.

You may have a vacuum leak that decreases or stops altogether once the engine is warm. Possibilities include the throttle body seal, manifold seals, injector seals, vacuum hoses, etc. You could also have dirty injectors.

Other possible causes include O2 sensors and the related wiring.