rising idle issue after manifold removal..

[ellisjay2]

Did a starter replacement on e36, m42 which involves removing manifold, after putting everything back together, i now have a rising idle issue when driving short distances. It rises up as I come to a stop or parking to where I have to go hard on the brake pedal when slowing down. Im thinking to go back and clean my ICV, though before I removed it when doing the starter the idling was normal. Checked all vaccum lines and sensors for leaks around manifold, throttle body as well, any other suggestions???

[Manolito]

Cleaning the IAC and throttle butterfly, and carefully inspecting all the air tubes from the MAF up to the throttle for cracks are the first step. Check the throttle position sensor and its plug as well.

If you find nothing, I know that a leak at the intake manifold gasket will disrupt the feedback that controls the idle air control. I've been there. You may have to pull the manifold back off.

[coolbear1]

I agree with Manolito on the throttle body butterfly, you could have dislodged some debris during the repair, and the valve does not go all the way closed.
But, I have to admit my knowledge of M42 is only what they have in common with a six cylinder.
M50 has a composite intake manifold that is very subject to hairline cracks that you can't see.
I have never had a 4 banger. They may have a metal manifold for all I know.
You did remember to plug the throttle position sensor back in?

[sweenrace]

I havent experienced this on either of my e36's but i have on race cars. For us, it was a result of sucking in air somewhere before the fuel charge gets into the cylinder. We often had issues with the inlet manifold not sealing against the head properly.

Good luck!