timing bouncing in maf only tune

[Aint Skeered]

Can some one look at my short log and tell me why my timing is bouncing up and down?

I thought I would start a thread just for this.

I am not sure if this is a good mass air or not, It was diagnosed as being bad by a tuner that could not fix my idle so he told me my maf was bad. It seems to be working , it is a stock 75mm 2000 f body maf with screen removed.

Am I mssing something in my tune or does it look like a bad maff?


This is on my chevy II nova. It is a race car only and am trying to tune with maf only. This is why I have the injectors scaled -6%. I am going to have to pull more from them, still on the lean side.

[5.7ute]

If you are talking about the fluctuations at idle they pretty well match your idle overspeed/ underspeed error.
Is this an auto or manual trans?

[Aint Skeered]

fI am talking about there and when I get on the throttle it surges up and down.

THis is a th350 8" converter that should flash around 5000

[5.7ute]

If you log an airmass pid like GM.CYLAIR_DMA it should give a better indication of why the spark is acting like that.
B5933 base spark in park/neutral may need a bit of work to smooth transitions into the high octane table as well.

[Aint Skeered]

Ok I will have to log that in pass through mode. I have not started changing and adding pids into the black box logging yet. WHat it came with is what I use from the last update

I am curious as to how many grams /sec its pulling in. WHen you say work on the base, SHould it be very close to what the high octane table ?

[mr.prick]

did you save that log after it was filtered?
everything looked herky jerky from TP% to MAP.

[5.7ute]

Not knowing what inputs the pcm is seeing due to the fitting of the th350 I am not sure which base spark table is being used. Hence the "may need work".You generally want a smooth transition from the base spark tables to the main spark tables.
Hopefully the BBL pid system will be automated soon to make it easier.

[joecar]

Post your Options.txt file... we'll edit it so to include DYNCYLAIR_DMA.

[Aint Skeered]

Joe the attachments manager keeps saying invalid file. I am looking in v8.1 Is this correct?

[Aint Skeered]

did you save that log after it was filtered?
everything looked herky jerky from TP% to MAP.

I have not filtered anything