A/F Issues when going into idle

[avanwinkle]

My issue is that I am getting some strange A/F readings just after going into neutral. From in the car, I just notice it going down to 850 RPM then jumping up to 1000 or so RPM, then back down to 850 RPM. It seems to be more pronounced when downshifting, then going into neutral.

Looking at the logs I can see that as soon as I let go of the throttle (while in gear), it changes to fuel status 4 (open loop - driving conditions), with the AF at 29.4. As soon as I put it into neutral, the fuel status changes to 1 (open loop - sensor warming up), the AF stays at 29.4. That looks fine, but what seems strange is that at the same time it changes to fuel status 1, it adds 3 - 5% fuel trim. A second or so later (while in fuel status 1) the AF will slowly get richer. After this the fuel status will change to 2 (closed loop); the fuel trim will shoot way up, (sometimes as high as 15%; and the AF will begin to drop. As a result of adding so much trim, the AF will get very rich for a few seconds. Eventually it will balance out and the AF will be in the 14.7 (+/- .1) range with the trim at 0 (+/- 1).

I can't see this as being an issue of tuning the fuel, because at the same rpm/MAP this issue is happening at, it runs fine (AF normal, fuel trim normal) when it idles for a few seconds. I could be wrong, but I have tried adding/subtracting fuel. All that does is make it so fuel trim will have be applied while idling.

I can't tell if this issue is coming from the sensor itself or my calibration. I'm also not sure when this started happening, possibly it has always been there since I reflashed it. I do know, however, that using an AFM calibration does not produce this issue.

p.s. Sorry for the long write up, but I wanted to be as descriptive as possible. The attached datalog should tell the whole story.

[Spunkster]

This looks perfectly normal to me. Try uploading a return to stock calibration and datalog and see how it operates.

[avanwinkle]

I'm completely fine with it if it's normal. It doesn't affect my driving. I just wasn't sure if this was a sign of a bad calibration. I was reading in your flash pro help section about adjusting the transition delay. I think the default is .5 or 1. But I have to set it to 7 seconds to get accurate readings. Is this normal?

I'll try the return to stock calibration and see how it compares.

I'm having a similar issue with how the lambda values are overlaid. I was trying to tune my cam at 0 degrees and I noticed I was getting very rich values shown under the part fuel section. Looks like this is happening when I let go of the throttle after accelerating. I isolated the attached screen shot and datalog. Is this normal? If it is, is there anyway to filter this out on the lambda overlay so I can do part fuel tuning?

I'm getting skunk2 stage 2 cams put on here in a month. I see an AFM calibration for it, but your help section suggest to use MAP calibrations with cams. Would I be ok to use the AFM calibration with these cams until I get it dyno tuned?