Originally posted by linky:
here's whats happen'n, when i start the car it revs up high and does'nt come down to correct idle till car gets warmed up, suspected iac, but cleaned and tested and seamed to be working fine. when starting to drive throttle starts to run away,reving high without downshifting and when it does downshift it slams into gear, got code542 and was going though troubleshooting for faulty fuel circuit, changed fuel pump and front o2 sensor, checked all electrical grounds. test circuit was fine. could this be a bad fuel pressure regulator? what are signs of a bad fpr. also car wants to overheat once in awhile, suspect bad cooling temp sensor,could this have a effect on wy the throttle all over the place.




542 (O,M) Fuel pump open, bad ground or always on - Power / Fuel Pump Circuits

This is checked at output of fuel pump relay. Remove battery and AUX box, you will probably find lots of corrosion underneath.

FPR is checked with pressure gage while engine is running. Bad FPR or missing vacuum usually causes extreme rich condition or flooding. Should have rich codes if this is the case.

ECT can cause rich condition and lack of codes, but usually gets worse as engine warms up.

Make sure throttle plate is closing completely. TB may be dirty or cable hanging up.

Replace rubber hose between PCV valve and UIM, and check for other vacuum leaks.

This kind of problem is the IAC, throttle plate, PCV valve, or a vacuum leak combined with a rich condition.

"Those who cannot remember the past are condemned to repeat it" -George Santayana