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Idle Control Using Scatter Spark

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Morning! I am new to the forum and gold membership after purchasing a course, thanks for having me. There is great info on here.

I am running a 2.0L 4 cylinder on omex600, I don't run an idle control valve and instead only use the throttle stop and then scatter spark to control the idle. I have always had a pretty good result with it.

The only issue is the car has to run very rich on cold start in order for the engine to not cut out when the throttle is blipped ( untill coolant temp rises then I am able to lean it out after 40-50 degrees Celsius for example)

I have now fitted aggressive cams to the car so I was wondering if there is any info or webinars on here which cover idle control using just scatter spark?! I know its a bit old hat but idle control valves can be unreliable and cause hunting which I have always been able to map out with scatter spark so I prefer it!

Thanks in advance


Not sure where the comment "idle control valves can be unreliable and cause hunting" comes from, that is not my experience. Typically the solenoid type valve is just a coil of wire and a single moving part so they are rarely un-reliable. Stepper motors arent my favourite, but again they are rarely unreliable. Surge could only be caused by a poor control system or poor tuning, not by the valve itself - it should flow exactly what your system commands it to.

Anyhow, be aware Idle ignition control is always going to have limitations when airflow is fixed. You only have a relatively small influence on torque to play with from advance alone. The best you can do to get it set up for the most torque influence is this: initially get the engine running with idle ignition (spark scatter) disabled, get the engine warm, set up the normal ignition map so it is idling very retarded - say around 0 deg if it is happy at that (keep an eye on EGT). Adjust the throttle stop so that it idles at about or just below the warm idle RPM you want to achieve with the absolute minimum advance you can use. This results in you having the highest idle airflow possible (which will help when cold). You can then enable idle ignition control, tune proportional gain etc to give good response to load changes such as fan switching on and add more advance when cold depending on what options your ECU gives you.

Hi Adam, thanks for your reply. MY statement about idle valve causing hunting was a bit of blanket statement, sorry for that. it is only in my limited experience I have had this, but maybe alot of that is because it is older cars that usually have an idle control valve and the control wasn't as good back then on OE management, or maybe just an age thing.

Thanks for the advise, sounds like a good direction for me to start in

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