engine over revs at start up
Thread Starter
Instructor
Joined: Sep 2006
Posts: 160
Likes: 2
From: Austin Texas
St. Jude Donor '08
engine over revs at start up
I have searched but have not found a solution. Push in clutch pedal, press start button, and as the tack and speedo needles sweep to the right and then back, the engine immediately revs to, by my guess, at least three, four, or more thousand rpms before dropping to the nine hundred idle it is set at. The colder the ambient temperatures the worse it is. If the engine is warm the overreving is not so bad, sometimes hardly at all. I have been easing the clutch out in gear so as not to grenade the engine, but I need to fix this. Checked for intake air leaks and could not find any. There seems to be an engine temperature factor involved. I have not done anything to the pretty heavily modified engine for a couple of months or so. This is driving me nuts, please help. Thanks.
_Sloth Whisperer_
Joined: Jul 2008
Posts: 3,369
Likes: 9
From: Malaysia Air Flight 370
It's in your tune. Your cold start tables are quite a bit different than your hot start tables. Tell whoever tunes your car that you'd like him to tune it to fall more quickly into idle on cold start up.
Drifting
Joined: Jul 2006
Posts: 1,786
Likes: 93
From: Charlotte N.C.
It sounds like the cold area of your start up idle airflow tables
Thread Starter
Instructor
Joined: Sep 2006
Posts: 160
Likes: 2
From: Austin Texas
St. Jude Donor '08
Thanks SlickShoes. Taylor at Dallas Performance did the tune several months ago, and the problem started quite a while after that and before the outside temp dropped below sixty or so. Because of those factors I am leaning away from the problem being the tune, but I am running out of ideas.
Thread Starter
Instructor
Joined: Sep 2006
Posts: 160
Likes: 2
From: Austin Texas
St. Jude Donor '08
Let me explain the problem a bit better, it is not that the idle falls too slowly, the problem is that the rpms get so high to begin with when the engine starts, once the engine starts and overrevs, it then falls to the preset idle fairly quickly.
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Thread Starter
Instructor
Joined: Sep 2006
Posts: 160
Likes: 2
From: Austin Texas
St. Jude Donor '08
Stock TB and no hole in the butterfly valve. I have looked and did not see a hole in the throttle body. Thanks all, looks like it is three for three on the tune. I will try to post a video, but it won't show much, other than a lot of racket for several seconds after start up or unless I ease out the clutch in gear.
_Sloth Whisperer_
Joined: Jul 2008
Posts: 3,369
Likes: 9
From: Malaysia Air Flight 370
Let me explain the problem a bit better, it is not that the idle falls too slowly, the problem is that the rpms get so high to begin with when the engine starts, once the engine starts and overrevs, it then falls to the preset idle fairly quickly.
Get back with Taylor and he'll fix you right up, I'm sure. Very well liked and capable tuner per all the Texas guys. New temps bring out all sorts of little nuances in a car's tune.
Thanks to Bobby @ LG too for pinpointing the exact tables.
Last edited by SlickShoes; Dec 10, 2011 at 03:37 PM.
Burning Brakes
Joined: Jun 2007
Posts: 823
Likes: 0
From: Seguin Texas
I had Chuck tune my '08 when he came to Texas a few years ago. No issues with weather at all. Tuners will always tell you they can tune as well as others, but it's unfortunately not true. Call Chuck.
