Hondata

hello. i had a problem yesterday with the idle on a car i was working on. the afr's were fluctuating and wouldn't stay stable.

i couldn't figure out what it was. i'm attaching a datalog of the car idling for 2 minutes. any help is appreciated.

Post the cal. I was having a similar issue but not as pronounced and to fix it you need to reindex the idle columns to keep the ECU from having to interpolate so much at idle. My idle is smooth as glass with ID 1000cc injectors and 70psi base fuel pressure.

soxfan143 wrote:Post the cal. I was having a similar issue but not as pronounced and to fix it you need to reindex the idle columns to keep the ECU from having to interpolate so much at idle. My idle is smooth as glass with ID 1000cc injectors and 70psi base fuel pressure.

I reduced interpolation with good results as well too. You may be aware, but just sharing for others to keep in mind that MAF shines in idle situations but the decreased resolution of MAP is more apparent, as in its normal for a MAP based car to have more fluctuation in IPW at idle due oscillations in the feedback system due to the MAP resolution. I say more relatively... when compared to the MAF sensor windchill affect which is increasingly accurate for smaller air flow amounts. 2-3 grams/second at idle says more to the ECU with regards to IPW then say -21.7psi.

Also the idle appears to be partly controlled by ignition advance/retard which also seems to have a mild affect on AFR due to charge combustion time, which adds to the seemingly increased oscillation.

I often see my WB02 reading 14.7 rock stable at cruise, but 14.4-14.7 at idle.

Steve