Standalone and M20 idle control

[zaq123]

Haltech Nexus S2 here. Does what I need and runs ITBs nicely. I tunned the idle in a similar fashion how stock Matronic does it, ICV never fully closed. My hot idle target is 900 rpm, ITBs set screw keeps the idle at 820 or so, Stock bosch ICV does the rest with being almost closed. Fully closed setting is 25% and I'm at 27%. Idles good considering 284 cam and ITBs. Ignition correction table and PIDs help to keep the idle on target and its ok in general all things considered, maybe 30-50 rpm or so as far as surge goes. Ignition sits around 10-12 adv and keep the engine nice and not super hot.
I was given a suggestion to actually meet the target with the set screw and keep ICV for cold starts only.

How do you guys do it and what's your thoughts?

[zaq123]

I was given a suggestion to actually meet the target with the set screw = ICV fully closed and keep ICV for cold starts only. Any thermal expansion in ITBs and idle change should be taken care by idle error timing correction table... in theory. More stable idle?


site wont let me edit my post :(

[digger]

i do as you have. IMO it should idle on the stops below your target say 100rpm with ICV not adding any bypass. The ICV then adds a little bit air to maintain target and it can both increase and decrese engine rpm based on changing ambient conditions, operating conditions and engine mileage

if you make it idle on the stops at the target then it gives no room to move the rpm down if the conditions change or as the engine gets miles on it it wants to idle a tad too fast. I tried this and it is not as robust, every now and then it it would idle a bit fast especially when super hot and heat soaked when the throttles housing would expand more than butterflies

[zaq123]

i do as you have. IMO it should idle on the stops below your target say 100rpm with ICV not adding any bypass. The ICV then adds a little bit air to maintain target and it can both increase and decrese engine rpm based on changing ambient conditions, operating conditions and engine mileage

if you make it idle on the stops at the target then it gives no room to move the rpm down if the conditions change or as the engine gets miles on it it wants to idle a tad too fast. I tried this and it is not as robust, every now and then it it would idle a bit fast especially when super hot and heat soaked when the throttles housing would expand more than butterflies

does your ECU have an option to add/subtract timing from the base to account for rpm of target error? timing change to keep steady idle is super responsive unlike ICV

[digger]

Mine doesn’t have ignition timing closed loop control. If that functions well enough to knock 100rpm off then it could work to do the same function.

I do have an elite 2500 to go in the coming months but a few other priorities first