My 2000 Protege 1.6, manual will start fine on a cold start. It runs fine through the cold start, warm up, operating temp cycle. It accelerates fine. It idles fine.
However, if I stop the car (warmed up) and then restart the car withing a roughly 2 minutes to 45 minutes time frame the car always start, but the idle swings between 400-1,200 RPM for about 10-15 seconds. After that the idle stabilizes and everything is fine for a complete drive cycle. It has been this way for about 6 months now and there are no codes. I have replaced the MAF (Denso) and intake hose without any change (and, yes, I did reset the ECU). I detect no air leaks anywhere. This car has no EGR (what people often recommend checking - please don't). It never had EGR and it passes strict California emissions visual test (just in case you are incline to think it has EGR).
I was thinking a leaking injector, but I kind of rule that out as once stabilized the idle is rock steady. It seems almost more time duration related as I have given the engine ample throttle and it takes the same 10-15 seconds to stabilize as it does if I just let it sit at idle. The other thing is if an injector is leaking then there would seem to be the same aspect a few hours later once the car re-starts in open loop and it doesn't. Nor with a depressurized fuel rail would the engine start immediately when cold - but it does. Any thought the O2 sensor is slow to warm on restart (still in closed loop) and causing the problem? There are no O2 sensor or O2 heater codes.
To summarize; colds start fine, runs fine. Only warm restart is the fluctuating RPM's and only for about 10-15 seconds then fine again.
Thanks for any help, Tom
However, if I stop the car (warmed up) and then restart the car withing a roughly 2 minutes to 45 minutes time frame the car always start, but the idle swings between 400-1,200 RPM for about 10-15 seconds. After that the idle stabilizes and everything is fine for a complete drive cycle. It has been this way for about 6 months now and there are no codes. I have replaced the MAF (Denso) and intake hose without any change (and, yes, I did reset the ECU). I detect no air leaks anywhere. This car has no EGR (what people often recommend checking - please don't). It never had EGR and it passes strict California emissions visual test (just in case you are incline to think it has EGR).
I was thinking a leaking injector, but I kind of rule that out as once stabilized the idle is rock steady. It seems almost more time duration related as I have given the engine ample throttle and it takes the same 10-15 seconds to stabilize as it does if I just let it sit at idle. The other thing is if an injector is leaking then there would seem to be the same aspect a few hours later once the car re-starts in open loop and it doesn't. Nor with a depressurized fuel rail would the engine start immediately when cold - but it does. Any thought the O2 sensor is slow to warm on restart (still in closed loop) and causing the problem? There are no O2 sensor or O2 heater codes.
To summarize; colds start fine, runs fine. Only warm restart is the fluctuating RPM's and only for about 10-15 seconds then fine again.
Thanks for any help, Tom