Idle Issues

[SoEm0]

Ok, I just finished doing all sorts of maintenance. TB, WP, head done up (valves adjusted, new seals), HG, and pretty much all other maintenance things. Now I go to fire the car up and the idle instantly jumps to 2k rpm. Nothing I do can get the rpm's to drop. Any guess why it does this? I searched for hours and have not found anything that really resembles this issue. Your help would be much appreciated, I would like to get this bad boy ready for BF.

[slammin.e28]

My guess is you missed hooking something up...I do that all the time.

...oorrr, did you use all new hoses? Like the CCV hose, intake boot, etc? If not, you coulda cracked one upon re-installation.

[SoEm0]

Yeah pretty much all new hoses except the radiator hoses

[SilentJon]

...oorrr, did you use all new hoses? Like the CCV hose, intake boot, etc? If not, you coulda cracked one upon re-installation.

it would barely run if one of the hoses or boots was cracked, not idle high

[browntown]

Drive it around and see if the computer learns maybe

[slammin.e28]

it would barely run if one of the hoses or boots was cracked, not idle high

Maybe if it was a wide open, gaping hole. I'm not talking the Grand Canyon. The ICV hose that goes into the throttle body (on that metal "L") likes to come lose and leak air. The CCV can crack at the terminating ends and cause a high idle. It's a small leak, not a gaping hole. The engine is getting slightly more air, so it runs higher, whether it is metered or un-metered.

[wildstoats]

By TB do you mean throttle body? If so what kind of maintenance was performed on it?

[slammin.e28]

By TB do you mean throttle body? If so what kind of maintenance was performed on it?

Yes, throttle body. The little metal "L" likes to come lose. It's only pressed in there, and they can come out/loosen up and create a small vacuum leak.



On the far left of the throttle body in this pic is one. There is another one (or two) on the other side for the vacuum booster.

[SoEm0]

No I meant timing belt. I got the idle down last night. I broke loose the idle adjustment screw and backed it off. Now she idles just fine, man I was stressing about this.

[hotballs]

Where is the idle adjustment screw? Didn't know an m20 had that...

[PNWDan]

No I meant timing belt. I got the idle down last night. I broke loose the idle adjustment screw and backed it off. Now she idles just fine, man I was stressing about this.

there isnt an idle ajustment screw. Theres a stop screw for the butterfly. You just compensated for the bad idle with it. The ICV controls how much air is let through. Sounds like ICV or TPS issue to me. Sometimes cleaning the throttle body can screw up the TPS if cleaner runs down the shaft and into it etc..

[SoEm0]

I adjusted that top screw to the specs i found in the bentley and its running great now