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<DIV id=post_message_6060820>I'm working on a 91 grand marquis with only 95k miles on it, bought it from an old lady that thought the transmission was going out but appearantly check the fluid level with the car off, added some fluid and it drove perfect, motor has tons of power and idles fine but it leaked alot and so does the tranny so i decided to pull the motor, clean it up and replace all gaskets. When i pulled the heads off, all the exhaust valves and spark plugs were white, which means its running lean, but why. There is no CEL and the smog pump is still connected but i noticed alot of carbon build up in the hole on the back of the cylinder heads almost blocking it up completely. My best guess is that the smog pump isn't pumping enough air in the exhaust and the O2 sensor sees a rich condition and leans the mixture. I'm taking the heads the get a valve job and dont want this to be a problem down the road, what else other than the partially block smog pump could be the problem?</DIV></TD></TR></T></TABLE>Edited by: dmc919

i would change the o2 sensors, and clean up your EGR passages and Idle Air Control valve on the intake. depending where you live, you dont really need the smug pump on the car and the holes on the back of the heads can be plugged. i would check timing on the engine also and make sure it is set correctly. there is a wire close to the distributor that needs the jumper pulled from it prior to adjusting the timing.would also replace the plastic grommet that controls the transmission pressure that attaches to the throttlebody. there is a brass replacement part to keep from burning up the transmission since the plastic one goes bad from ageand getting brittle.