mikellinos
15+ Year Contributor
- 60
- 18
- Apr 20, 2010
-
LM,
Europe
I know the Series 2 is an old platform but many people still using it, at least i am and i still like it. I want to provide some information that I haven't seen nowhere else and i know many still have a bit of a hard time to tune the idle.
Below you see some measurements I did with different Idle max steps and the affect on the Idle Valve range of motion and how they affect the table idle% vs target.
Idle max steps - idle valve protrusion at 99.6% target - protrusion at 0% target - useful % at the idle% vs target table
50 - 33mm - 35mm - 0%-15%
80 - 31mm - 35mm - 0%-27%
90 - 31mm - 35mm - forgot to check
100 - 30mm - 35mm - 0%-35%
120 - 30mm - 35mm - 0%-41%
160 - 30mm - 35mm - 0%-58%
180 - 30mm - 35mm - 0%-66%
220 - 30mm - 35mm - 0%-80%
225 - 30mm - 35mm - 0%-94%
As you see the range of the Idle% vs Target table it is not always all in use, in our case with DSM 1G ISC which has 120 steps 0% represents a full closed valve and at 41% we have a full open valve. So lets say you tune you idle at operating temperature and 800rpm and the idle valve is at 30% you have already almost maxed out the valve and probably wont be able to increase your rpm enough when the engine is cold or during a start up.
What i personally do is to adjust my idle, in my case 1200rpm, with a warmed up engine and the idle valve at 7%, this will let sufficient range for the valve to open enough at cold start up and accessories on (lights, radio, A/C) which will raise the rpm at 1900 and the valve will be between 35-40%. This also will let sufficient air to bypass the throttle during start up (Rpm Offset vs Start table) and let the engine start without touching the throttle pedal.
Hope the above helps, cheers!
Below you see some measurements I did with different Idle max steps and the affect on the Idle Valve range of motion and how they affect the table idle% vs target.
Idle max steps - idle valve protrusion at 99.6% target - protrusion at 0% target - useful % at the idle% vs target table
50 - 33mm - 35mm - 0%-15%
80 - 31mm - 35mm - 0%-27%
90 - 31mm - 35mm - forgot to check
100 - 30mm - 35mm - 0%-35%
120 - 30mm - 35mm - 0%-41%
160 - 30mm - 35mm - 0%-58%
180 - 30mm - 35mm - 0%-66%
220 - 30mm - 35mm - 0%-80%
225 - 30mm - 35mm - 0%-94%
As you see the range of the Idle% vs Target table it is not always all in use, in our case with DSM 1G ISC which has 120 steps 0% represents a full closed valve and at 41% we have a full open valve. So lets say you tune you idle at operating temperature and 800rpm and the idle valve is at 30% you have already almost maxed out the valve and probably wont be able to increase your rpm enough when the engine is cold or during a start up.
What i personally do is to adjust my idle, in my case 1200rpm, with a warmed up engine and the idle valve at 7%, this will let sufficient range for the valve to open enough at cold start up and accessories on (lights, radio, A/C) which will raise the rpm at 1900 and the valve will be between 35-40%. This also will let sufficient air to bypass the throttle during start up (Rpm Offset vs Start table) and let the engine start without touching the throttle pedal.
Hope the above helps, cheers!
