A few months ago I had my intake manifold gasket replaced because my engine was revving high during idle.

Now it is revving low during idle. When I first start the car I have to rev it up to keep the engine going or it will stall. After the engine warms up it will idle only at 300-400 rpms.

Autozone's engine reader showed P0506

Definition - IAC circuit condition or idle speed higher/lower than expected

Explanation - The ECM has detected that the IAC counts are higher or lower than expected, the engine speed is not in is expected range.

Probable Causes

1. Vacuum leak on engine
2. Dirty throttle body
3. IAC motor defective
4. Poor electrical connection on the IAC valve


Does anyone know how to test these items or have any other suggestions.

Thanks,

 

1) Spray throttle body cleaner around intake manifold to see if it is leaking again (though indeed this will usually lead to a high idle if the leak is small)

2) Use the throttle body cleaner from 1) above to actually clean the throttle body

3) and 4) Check for proper electrical connection at the IAC on the throttle body. The IAC and PCM communicate to ensure the idle speed is within range (850 +/- for a manual for example). If the IAC is disconnected or has gone south, the communication is not there.

Did you have any other service performed recently which might have entailed someone bumping the IAC connector or intentionally disconnecting it while working on something else in the area?

 

It wasn't working perfectly after the shop installed the intake manifold gasket. Would they have disconnected or bumped the IAC while doing that?


The did say they wiped the throttle body out, but I don't know if they actually cleaned it.

 

They may have damaged IAC it if they were not careful

 

After Cleaning the Throttle body I found a few things.


1. The IAC is Chipped on the plastic.
2. The IAC does not move when the key is turned to run position.
(read in another post that it is supposed to.)
3. Rust colored material in intake tube and small tube running to engine.
4. Throttle body gasket "wet" with the same material as in the tubes(not sure).

 

I put everything back together today. Now I think I hosed up the IAC for sure. At startup It revs up to 2000 then increases quickly to 4000. Is it the IAC or is something else messing it up.

Thanks,

 

sounds like a vacuum leak

 

Hi. Is it normal if i'm driving 40 mph on N and rpms around 1200? And rpms goes down slow when i switch from gear to N.
Is it normal?

 

sounds ok to me -- except that you can't drive 40 rpm in neutral.

And this isn't your thread.

Start your own thread, please.

Oh -- do you still do painting and handywork in the Newark, Delaware area?

And is your day nursery situation all settled, then?