New motor/cam/ls1 Edit?
Thread Starter
Launching!
Joined: Feb 2003
Posts: 243
Likes: 0
From: Fresno,CA
New motor/cam/ls1 Edit? Now i know this question has probably been asked a lot, but i couldn't find anything on a search. I just started my set up for the first time. 408ci 224/230 .568/.573 114lobe cam etc. I can seem to get it to idle without dieing. I have the idle set at 950 rpm, but every time i slow down i have to keep my foot on the gas for a few seconds. I have ls1 edit, but i am not sure what tables need to be adjusted in order to make this thing idle. For those of you that have done these types of setups can you please give me a little info on what needs to be adjusted.
Re: New motor/cam/ls1 Edit? Your idle speed setting in LS1edit is good, but it needs more air at idle. Adjust the the idle speed screw or drill out the hole in the blade bigger until the IAC count is in the 30s. A little more ignition timing should help also. If it still has problems, adjust the VE table slightly.
On The Tree
Joined: May 2003
Posts: 106
Likes: 1
From: Apache Junc, Az
Re: New motor/cam/ls1 Edit? Take note of your IAC counts. In a no load situation (neutral, no ac) you want them no lower than 30, and no higher than 50. You may need to drill a hole in your throttle body/enlarge the one that is already there to bring down the IAC values like Cal sez. Do this until they are acceptable. Now put a load on your car (D if automatic, and put the AC on). The values here should be no higher than 120 or so. If they are enlarge the hole. Repeat the above process until your IAC values fall inline.
Otherwise/also -- If you are still not happy with the idle you can try adjusting the timing. Be carefull of adding to much timing - it can give you a great no load idle, but with any kind of load will become erratic. A erratic idle is a tell-tale sign of too much timing. To adjust the timing at idle the base spark tables are the easiest place. The tables are scaled vs. rpm and g/cyl of airflow. The rpm part is evident. To calculate the g/cyl use the following formula g/cyl = 15 * MAF(g/sec) / RPM
This formula takes massflow per unit time and converts it to massflow per cylinder. The 15 is a constant which corresponds to the characteristics or a V8 running a 4 cycle combustion cycle. The easiest thing to do is to load your log file into excel, export to CSV, then create a formula in excel which applies the formula above.
Good luck
Otherwise/also -- If you are still not happy with the idle you can try adjusting the timing. Be carefull of adding to much timing - it can give you a great no load idle, but with any kind of load will become erratic. A erratic idle is a tell-tale sign of too much timing. To adjust the timing at idle the base spark tables are the easiest place. The tables are scaled vs. rpm and g/cyl of airflow. The rpm part is evident. To calculate the g/cyl use the following formula g/cyl = 15 * MAF(g/sec) / RPM
This formula takes massflow per unit time and converts it to massflow per cylinder. The 15 is a constant which corresponds to the characteristics or a V8 running a 4 cycle combustion cycle. The easiest thing to do is to load your log file into excel, export to CSV, then create a formula in excel which applies the formula above.
Good luck
