Re: rough Idle
Le Mans Master
Joined: Jan 2006
Posts: 5,620
Likes: 206
From: Orlando FL
When the engine is cold in open loop the A/F ratio is derived from fixed tables and parameters, engine temp, TPS and RPM (etc). So the O2 sensors are not utilized yet and perfect A/F is not calculated.
You have also changed you exhaust system which I believe will affect this whole situation. The chip may not take into account the new exhaust and different 02 readings.
This link will explain much more in greater detail.
http://www.gnttype.org/techarea/faq/BLMINT.html
Last edited by pcolt94; Apr 15, 2009 at 03:53 PM.
Le Mans Master
Joined: Dec 2006
Posts: 5,139
Likes: 482
From: H-Town Texas
You said you put headers on it, do you have the o2 bungs connected to the headers? Or are they non-emission? If they have the o2 connections, try getting some o2 sims. These will send a false signal to computer.
With the Hotcam, my cold idle is fairly smooth, but that is in open loop at a higher rpm. Once it goes into closed loop (warm) the rpm cuts down and the idle gets lopey. That's what bigger cams do.
The specs on the Hotcam are 218/228 Int/exh duration, .525 lift on 1:6 rollers and 112 lobe seperation. If your cam is bigger than this with a wider seperation you're going to get more "lope".
You said it runs great when you "give it hell". So it sounds to me like it's doing what it's supposed to do.
With the Hotcam, my cold idle is fairly smooth, but that is in open loop at a higher rpm. Once it goes into closed loop (warm) the rpm cuts down and the idle gets lopey. That's what bigger cams do.
The specs on the Hotcam are 218/228 Int/exh duration, .525 lift on 1:6 rollers and 112 lobe seperation. If your cam is bigger than this with a wider seperation you're going to get more "lope".
You said it runs great when you "give it hell". So it sounds to me like it's doing what it's supposed to do.
