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Hi all, any tips for idle control on BMW M42 race engine. No DBW and using ITBs with aggressive cams. Not worried about driveability As it’s a dedicated race car. More that I’d like to be able to warm the engine up without constant stalling. ECUMaster EMU Black.
im new to this!!
You may have an option to drive a stepper motor in the ECU that can be used to control the idle speed? If you're fortunate it will be possible to have the idle speed change with temperature.
If there isn't the option, you may be able to use a simple solenoid that you can use a manual switch to energise to raise the idle speed. That would be purely on-off, though.
Last option, a brick on the throttle pedal.
Option three is pretty close to how I managed warm up on my old non-standalone ECU race car :-)
Thanks for the reply. I’m running RHD ITBs and no easy option to integrate any electromechanical devices to the throttle.
was hoping there may have been some clever manipulation of timing etc that might assist.
worse case scenario I’ll adjust throttle cable to have a permanent fast idle.
Most ECUs can do ignition-based idle control if there isn't an DBW or idle air-control available. In the ECU Master EMU Black software, you would set the target Idle Speed with table Idle->Idle Target TPM, and use Idle->Ignition control to tick "Enable Ignition Control". Play with the Max /Min values and change rate to see what happens. Be sure to click the help for the Ignition Control parameters, it describes this in more detail.
You can also tune the idle ignition using the table Idle->Idle Ign. Corr. -- Using that table you tune how much ignition advance to add when below the target speed, and how much to retard the ignition when above the idle speed. I would let the idle control system handle things within 50 RPM, and use the table when it's off by larger amounts.
On another brand of ECU, I have values like a few degrees of change if within 50 RPM, and as much as 20 degrees of change if I am a few hundred RPM away from the target.
Just open the throttle enough so the engine can run at a fast idle for cold starts, then retard the ignition as required to hold the RPM down somewhat (you won't get street-car idle, but should be able to reach 1000-1500 RPM I would think for most race engines.
David thanks for taking the time to provide such a thorough and knowledgeable answer. Really appreciate it !
You're welcome, glad to help.
To be clear -- I just downloaded / installed the software and looked for controls that would do what I knew needed to be done. I've never actually used an ECU Master ECU, but I have used several other brands, and after a while, you understand they generally have similar features.
To add a little to what David mentioned, I do mostly ITB engines.
To ensure you get enough torque authority with ignition control alone, for initial set up, with a warm engine I adjust the throttle stop so that I have the target idle speed with very little timing - often 0 or 5BTDC, whatever the engine is happy with. This then means the throttles are more open so you enough air flow potential to acheive the largest margin of torque increase by adding timing when it is needed.
Im not sure what tables the ECU master has for idle ign control but you would also typically need some sort of coolant temperature based adder to add about 25-35deg to that timing at low engine temperatures to achieve target idle speed. Even then you dont always get total ability for cold start without touching the pedal.