Need help with idle, surges bad.
Need help with idle, surges bad. I am needing some help. The car is a 1999 TA with FAST intake, headers, exhaust, and the cam I have is a 228/228 588/588 112 LSA.
It is kind of weird. The car idles fine for the first 10 to 15 seconds then all of a sudden it will start to surge pretty bad up and down and sometimes will cause the car to die. Then after about 2 to 3 minutes it will idle pretty good. If I let the car sit for maybe 5 to 10 minutes it will do the exact same thing. It takes 2 to 3 minutes then the car will finely idle. What is bothering me is that the car will eventually idle but it takes a while. Any idea what I need to look at?
It is kind of weird. The car idles fine for the first 10 to 15 seconds then all of a sudden it will start to surge pretty bad up and down and sometimes will cause the car to die. Then after about 2 to 3 minutes it will idle pretty good. If I let the car sit for maybe 5 to 10 minutes it will do the exact same thing. It takes 2 to 3 minutes then the car will finely idle. What is bothering me is that the car will eventually idle but it takes a while. Any idea what I need to look at?
word, start with basic idle tuning.
base airflow table, ignition timing, etc.
with proper tuning cams far more aggressive than that will idle fine.
dont forget to check for vacuum leaks too.
base airflow table, ignition timing, etc.
with proper tuning cams far more aggressive than that will idle fine.
dont forget to check for vacuum leaks too.
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Joined: Aug 2005
Posts: 1,691
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From: Sunny London, UK
Yeah the fact it starts nice means its getting extra startup air. Its probably not got hot enough to move down the RAF table, so you probably need to add more air into the RAF table to handle post startup air reduction.
Whats the history? Is the cam recently installed?
Whats the history? Is the cam recently installed?
Well, I decided to try a 2001 computer (I had laying around) in the 99 to see if it would idle any better and it did. It idles perfectly with the SAME EXACT stuff done to the pcm that I did to the 99 computer to get it to idle correctly. I noticed in LS1 Edit that some of the tables in the later model computers have more you can adjust. I guess I will be trying to find a 2001 and newer pcm.
Last edited by c5ls1vette; Jan 2, 2007 at 08:48 PM.
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