this is more out of curiosity than an actual effort to fix this, this engine is a lost cause...

After driving home today, I pulled in the driveway and put it in park. Idle rose a bit, like it normally does, then ran rough for a second or two, ran perfectly fine after that and threw a cel. Scan tool said "P0507- Idle air control RPM higher than expected." Ive never seen this before, even in the shop I work in. What could cause this?

Should mention this is an EJ22E swap into a car that origionally had an EJ25D. I had to swap the IAC valve from the 2.5 to the 2.2 as it was not working on the 2.2. Apart from that in the beginning, this is the first non-emissions related code its thrown. Ill just assume that this is a funky thing that happens by running an engine in a car whos ecu wasnt mapped out for that engine.

Thanks for any input

Edited January 4, 201511 yr by pginter96

If you had a Saturn with a P0507 code, I'd tell you that you have an intake manifold gasket leak.  The Saturn SL1 engines are famous for this.  The code means that the ECU detected a high idle for two minutes or more.  A vacuum leak around one cylinder tends to confuse the O2 sensors so they end up dumping extra fuel into the manifold which causes the idle to rise up.

 

But it could be the IAC was well.

clean your iac thoroughly and make sure you don't have any loose connections or cracks in the hose to iac.

 

O.