We have a 1996 Saturn SL 1.9 SOHC with a idle problem. We are getting a P0507 code (IAC shows RPM excessive). We cleaned the throttle body and replaced the IAC. The idle is still too high. It should be 500 - 600 in neutral, but is over 1000. We can't find any vacuum leaks and have manually adjusted the idle as low as we can & it's still too high? Anyone have any ideas? We're stumped.

:banghead:

P0507 basicly means that there is a higher than wanted idle and the system is not able to get it to where it should be.

It is very common for a SOHC to have a vacuum leak at the intake manifold gasket.Take a spray can of brake clean and carefully sprayed in the area of the intake manifold.If the idle changes you have a bad intake manifold gasket.

You have made the classic mistake of replacing a component simply because that component is mentioned in the DTC description.

You cannot manually adjust the idle. You have to fix the problem which is most likely a vacuum leak that the PCM is having trouble compensating for. My guess is intake manifold gasket but you could also have a broken or missing vacuum line down under the intake that's only visible if you get under the car and look up.

first, put the idle set screw back to where it was.

the common intake gasket leak affect the later engines, 99 or 2000 and up, it is still possible, but unlikely.

but keep looking for a vacuum leak, a can of carb cleaner can be very useful

I recently had the same problem with a car at my shop. I replaced the TPS(throttle position sensor),and it solved the problem. if you have any other questions you can email me at alexmurra@yahoo.com. Also here is a link that may help you. http://autozone.com/N,4294897512/shopping/locsSelect.htm

Hear is a test you can do to diagnose a bad TPS.When it is idling high shut the engine off and restart it.If the idle returns to normal you have a bad TPS.Or while the engine is running you can tap on the TPS with a screwdriver handle.If the idle changes you have a bad TPS.

WE FOUND THE PROBLEM!!!

The EGR valve had a broken base....that was the vacuum leak. We had to replace the valve even though it was fine, the white metal base was broken where it fastened to the intake.