- Fri Jan 22, 2021 1:42 am
The recommended procedure to adjust idle for some stock ECU´s with PWM valve:
1. warm up engine to normal temperature.
2. disconnect idle valve.
3. adjust engine idle 50 rpm lower than normal, manually. This may be a dedicated screw or at the butterfly in some cases.
4. check for correct CO / lambda.
5. connect idle valve and check for correct rpm. Check CO again.
If you modify this procedure in step 5, you can find the base PWM setting for your idle valve. This might take quite some time, if you do not know the recommended frequency for your specific valve. Maybe measure it on a stock installation.
PS the idle valve is always triggered to prevent it from sticking. Some ECU types run it on 100% for a short time at start up, to clean out any dirt/ sludge that may build up inside. WD40 is great to clean these valves internally, run them on 100% and inject into both sides. Be careful with polarity! Some have a build in diode to protect the ECU/ kill spikes directly where they are produced. This is impossible to measure from the outside with a simple DMM. Look for polarity markings at the connector or check in the work shop manual.