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Idle Hiccup

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Old Sep 23, 2004 | 10:23 AM
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Question Idle Hiccup

Fellas, I got a little problem with my idle that I'm not sure what's going on or how to address it. When the car is just idling it's fine (750rpms). The car's an M6, when I have it in neutral and I hit the pedal to rev it a little, when the idle comes back down it will dip below 750, around 500rpms, and then go right back to 750. I did everything NoGo recommended except adding two degrees of timing (I tried that and the car seemed to idle worse). Anyway, what may be causing the idle to dip like that for a split second, and how do I fix it?

Thanks!
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Old Sep 23, 2004 | 12:51 PM
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to the top
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Old Sep 23, 2004 | 12:56 PM
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try 850 or 900 rpm and see if that helps what size cam are we talking. Have you messed with the decay? What have you done to the ve table?
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Old Sep 23, 2004 | 01:03 PM
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I had it at 850 but lowered it to 750. You're right, it didn't do that at the higher rpm, but I want my car to idle at 750. I could always go back to the higher idle if I can't make this work.

I multiplied x70%, x80%, and x90% in the ve table for 400, 800, and 1200 rpms. I did the other stuff NoGo suggested except for adding the 2* of timing. I haven't messed with any decay table except the one for torque management. Also I drilled my throttle body to 3/16".

Thanks HumpinSS.
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Old Sep 24, 2004 | 03:59 AM
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So I assume that raising my idle is the only solution?
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Old Sep 24, 2004 | 04:57 AM
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What is your A/F ratio at the lower rpms? Do you have a wideband.
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Old Sep 24, 2004 | 05:31 AM
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Good question, no wideband. You mean idle rpms a/f ratio? I've leaned it out with the ve table, plus I drilled the throttle plate. I could probably figure it out.

I was hoping someone had experienced this and found a solution, but I think most people just increase the rpms, which I could do, and have done, but I'd rather idle at the lower number.

Anyway, thanks.
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Old Sep 24, 2004 | 08:48 AM
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The computer may be having a hard time keeping you at 750 idle. Most manual cars idle at 800-850 anyways. I dont think the iac is fast enough to catch the car before the idle plummels down. Try decreasing the idle air flow tables by 10% and see how that goes
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Old Sep 24, 2004 | 03:28 PM
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Thanks for the help.

I raised the idle to 825. I think I can live with that just fine.

Thanks!
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Old Sep 25, 2004 | 11:11 AM
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Someone in here knows, I wouldnt give up yet
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