How should an M20 idle anyway?

[15Michaeljoseph]

I think the intake itself really makes a whiney kind of sound.

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[THMotorsports]

My m20 idles perfectly steady at times, but other times it will jump around.

I'd say 98% of the time when i put the car in neutral and roll to a stop, it bounces between 400-1100. Sometimes it'll settle down and sometimes it will continue to jump up and down while stopped. What could be causing this? Some days i start her up and she idles right at 650-750 the entire time (gave a range of RPMs assuming the needle may be off a little bit). I also notice that when i push the gas initially, the RPMs tend to drop before they go up. Not sure what's going on with it, but it's driving me nuts! Any ideas what could be wrong?

[crappycoco]

Vacuum leaks =) Smoke the car and watch for leaks. Especially around the throttle body and ICV. Or just do a search on r3v: "idle", "vacuum leak", ... Has been covered extensively. Find the post by jlevie - he wrote down the whole troubleshooting procedure in one giant post.

[THMotorsports]

Vacuum leaks =) Smoke the car and watch for leaks. Especially around the throttle body and ICV. Or just do a search on r3v: "idle", "vacuum leak", ... Has been covered extensively. Find the post by jlevie - he wrote down the whole troubleshooting procedure in one giant post.

Awesome thanks!

[Kershaw]

If you let off the brakes after coming to a stop, does the idle normalize? Is it only jumping while holding the brakes down?

[THMotorsports]

If you let off the brakes after coming to a stop, does the idle normalize? Is it only jumping while holding the brakes down?

The brake doesn't seem to affect it at all. It's really weird. This morning the idle was completely normal again. The ONLY time the RPMs jumped was when coming to a stop. Once i throw the car in neutral, it drops down to around 400ish RPMs, bounces up to 1100ish RPMs and just keeps doing that. From time to time it'll stop and idle smooth (as smooth as a m20 gets lol) but other times it'll continue the bouncing at idle.

[Kershaw]

If you're sitting at idle and you put the clutch in does that change anything?

Does it only jump around with the clutch out and not in gear? Could you replicate the same behavior at speed by putting it in neutral and releasing the clutch? Or does it only happen when you're not moving and at idle?

[THMotorsports]

If you're sitting at idle and you put the clutch in does that change anything?

Does it only jump around with the clutch out and not in gear? Could you replicate the same behavior at speed by putting it in neutral and releasing the clutch? Or does it only happen when you're not moving and at idle?

At idle if i push the clutch in, it won't replicate the problem. It's only when I throw it in neutral to "coast" or come to a stop.

[supermansocks95]

I think the intake itself really makes a whiney kind of sound.

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Yeah, my girlfriend does that too. Just tell the intake to shut up and give it a slap on the butt for good measure.

[THMotorsports]

Yeah, my girlfriend does that too. Just tell the intake to shut up and give it a slap on the butt for good measure.

[15Michaeljoseph]

Yeah, my girlfriend does that too. Just tell the intake to shut up and give it a slap on the butt for good measure.

Hahahahaha

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[redfoxiii]

The only thing that drive me nuts is the slight drop and bog if the throttle is snapped off of idle.

Actually, that bog/drop is due to the airflow censor flap (on top of the air box) opening and closing. It's especially noticeable if you bob the throttle repeatedly while under the hood, the car will almost stall. The only way to get rid of it is to do a MAF conversion.

[15Michaeljoseph]

Actually, that bog/drop is due to the airflow censor flap (on top of the air box) opening and closing. It's especially noticeable if you bob the throttle repeatedly while under the hood, the car will almost stall. The only way to get rid of it is to do a MAF conversion.

Wow! I always thought it was because my car is a piece or that the ECU or AFM was on its way out... Good to know!


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[Downeaster1]

This thread has been far more helpful then I would have thought. Especially for a bunch of people typing out sounds haha

[Seawolf]

Yeah, my girlfriend does that too. Just tell the intake to shut up and give it a slap on the butt for good measure.

Ha ! Wait till you marry her....all wives upgrade to forced air and a Magnaflow :(