BackInBlack02

iTrader: (4)

I need some help troubleshooting engine issue, maybe this happened to someone before.

when its cold and for the first 5 to ten min. of driving, it drives fine, once it the temp needle starts moving, the engine starts hesitating or stumbling but with a little more gas it moves just fine then hesitates again like not all cyl are firing. Also, I'm smelling a lot more exhaust than before. It almost feels like the cat is plugged but I figured if that was the case it would run the same warm or cold. I think it would be the same case for a dirty fuel filter.


--Just read another thread about a similar issue, got to check the O2 sensors.

any other ideas?

thanks.

SS RRR

iTrader: (2)

Two easy checks:

Jack car up with jackstands and check to make sure w/p is not leaking onto opti. Mine would be have the same way. What would happen is it would run fine when cold, but once pressure started building in cooling system it would leak from the w/p onto the opti causing the engine to stumble yet would be fine at full throttle. You should see coolant stains out of the weephole of the w/p and surrounding areas if it is indeed leaking.

If that checks out, unplug the O2 sensors and drive around again and see if it still behaves strangely.

BackInBlack02

iTrader: (4)

thanks, got EWP, I'll try the O2 check.

SS RRR

iTrader: (2)

EWP has a weephole too (at least mine does).

BackInBlack02

iTrader: (4)

Thanks, I'll check the EWP too.

Catmaigne

iTrader: (6)

...Or you could just unplug the MAF to send the car into open loop. It's much easier and does the same thing to the PCM. Your problem sounds like a faulty sensor in the FI system.

BackInBlack02

iTrader: (4)

Thanks for the input, it turned out to be the O2 sensor on the driver's side.

lethal bird

iTrader: (12)

Same thing happened to me a while back.

BackInBlack02

iTrader: (4)

I thought for sure it was a vacuum leak at the intake and just could not find it. I replaced both O2 sensors, problem solved.