Funny Idling

[SHR XTC]

I have my 93 Q45a in the shop and noticed that car was idling funny.

I would have the engine running, transmission in park and once it warms up, the idles goes upto about 1200 rpms then drops to about 500 rpms. I feel the active suspension going up and down as the idle goes up and down. It would do it for about a minute then the idle would return to normal then a few minutes later it would do it again. What do you think it can be??

The mechanic said he is going to check it out but I'm concerned about it. By the way, the Q was in the shop getting a tune up and the brakes done. Do you the mechanic could've touched something to cause this??

Please let me know, any info would be greatly appreciated.

Thanks~~

[DAEDALUS]

What did the tune-up involve? Just replacing the plugs is no small amount of work; maybe something was disconnected and left that way. Have you tried jiggling the MAF sensor connector on top of the airbox? Look for vacuum leaks too.

[landtodd]

Ditto the electrical connector to the MAF. Had the same problem last week, cycled the connector, and it's back rock-stable for the time being.

Many thanks to this group for drilling it into my head over the last two years that this connector is problematic.

[SHR XTC]

Thanks for the replies!!!I agree with you guys.The mechanic thinks it's the Idle Control Sensor.He's gonna check both out.I'll keep you informed.

[Q45tech]

What idle control sensor? there is no such thing the ecu calculates the idle speed from CAS vs coolant temperature.

Careful more damage is done by Quasi mechanics: only years of Q experience or factory school trained should be allowed to get anywhere near a Q engine.

Ask if he has a Consult with the correct active plug in card .....NO.....run away fast! Even a half a turn on one of the 3 TB hot/cold/liftoff screws will cause problems.

[greg_atlanta]

Who's the mechanic? What's a "tune up"??

Your car is more sophisticated than most new cars. I'd be very picky and choosy about who works on it. Very few mechanics decline work because they enjoy the adventure.

[SHR XTC]

I thought he said ICS but he said Vacuum Leak.Sorry to spook you guys!! :pface

Thanks for the head up!! :ylsuper