Ok I have a 94 SL, which if I keep the AC on keeps my Idle down to the normal Range 600-700 RPM, if I turn the off the AC I will get a High idle after driving up 1100 RPM for a few secs which will throw on the CEL. I have changed my TPS Sensor, Any Ideas?

 

Do you get any codes from the OBD system, or is the CEL the only indicator?

 

Check for a vacuum leak around the intake.

 

To clarify Rubehayseed, spray something like a carburetor cleaner or even WD-40 around the intake manifold gasket, especially around the #1 cylinder and see if it affects the idle. The intake manifold gaskets are prone to getting sucked in at the #1 intake port because it is not well supported and it only has three bolts around the port instead of four as the other cylinders do.

 

Ocean- CEL, it is OBD I so 34 flashes if i remember correctly, and it was just saying high idle

Ruby and Kieth, do you have a picture of where this would be. Every time I search online I just find stuff for the SL2 engine DOHC

 

Cly number 1 of your intake manifold. If you need a "picture" you may need someone helping or doing it for you.

 

Sounds like a possible bad connection between the ECM and the MAP sensor, or the MAP sensor itself may be defective ...