intermitent stall & code 542

[jeremy manlief]

i have a 95 mtx. for about the past week, my sho has been stalling sometimes. the car runs great and when i am driving down the road and come up to a stop light, i am just waiting for the light to change and all of a sudden, my car stalls for no reason. it starts right back up and runs the same as it did before it stalled. one time i was ready for it and it tried to stall but i kept it running by goosing the gas when it tried to stall. i have a new cps, cid, o2 sensors, no oil in plug wells, and numerous other new parts on the car. about 2500 bucks worth. i ran all the tests and got a code 542. has anybody had the same problem and what was the fix. my car has 146,000 on it and runs great with the exception of this problem. thanks everybody.

 

[Rockledge]

Many times the 542 code is simply the result of stall condition. So I have to think it might an Idle Air Control (IAC) issue.

 

[Markus]

Is 542 the only code you're getting?

 

[jeremy manlief]

yeah. that is the only code that i received when i did the tests. i also checked my fuel pressure today and with the engine off/key on i am getting 40 psi when the pump kicks on and drops to about 32 psi when the pump stops priming. from there, the pressure drops to zero in about 2 minutes if you dont start the car. is this normal? when the car is running, the fuel pressure is at 42 psi. i was also leaning toward the iac since i havent had a chance to clean it.

 

[projectSHO89]

That rate of leakdown is not normal, but is probably not the reason for the stalling.

I'd suspect the IAC as it is a very common failure.

Steve