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Hi,
Are there any tips for tuning idle with no DBW throttle or idle stepper bypass?
This is for my circuit car which has big cams so I don't expect it to idle below 1000 but would like to know tips for keeping it steady.
Thanks
Karl
- Try running a little richer - ignore the O2 reading with big cams at idle, just tune for a smooth idle without any pops.
- Build an ignition trough, more advanced below your target idle speed, and slightly retarded just above the idle speed.
- If it surging, first try increasing the ignition timing (perhaps there is an overall trim you can just try), then lower the throttle to reduce the RPMs. if that doesn't help, put it back and try opening the throttle a little (with the throttle stop), and then retard the ignition to bring the engine speed down.
Idle is a tricky balance between torque generated (air, ignition timing) and mechanical load on the engine (varies with RPM).
Good Luck!
You may find some of these points, and other good ideas (even if you don't have DBW or IAC) from this webinar:
https://www.hpacademy.com/previous-webinars/207-getting-the-perfect-idle/
Thanks very much for the insight. I'll let you know how I get on....
As above, wind the throttle stop in to open it a bit more, target ~0.85 lambda if it's got a lot if cam/port, soft timing at/above target speed so it's stable but won't droop to much with added loads.
