hey guys, need help before I go racing tomorrow

[tgeers]

Hi
I know you all can help. I was at the track tonight trying to get my WOT dialed in. I'm running the SD program. Here is the problem. During a pass down the track at WOT I can get widely varying AFR readings when the RPM, MAP, TP, and MAF air are all realatively constant. Neither does the spark advance or command AFR change either. For example, at 5000 rpm and a MAP reading of 98, I could get an AFR reading of 12.5, and then get an AFR of 11.5 without leaving the same VE cell. Is this normal, OK? If not, what should I be looking at to correct it? I'm going racing tomorrow afternoon and would like to try and correct this if I can.

Thanks for looking at this post and adding your comments.

Tony

[Tordne]

Were the varying AFR's on the same run? If they were different runs It could be that the IAT temp was higher or lower?

What OS # are you running?

Are the cells surrounding the current one smoothish? The PCM interpolates between the surrounding cells so if these are large peaks or troughs that can affect things also.

Just a couple of suggestions to start with.

[tgeers]

Thank Tordne for your suggestions. The changes in the AFR are in the same run and occur within a moment of each other. Perhaps the smoothish suggestion is a possible answer. Here is one example:

At 5107 rpm and a Map reading of 98, IAT 30C, Command AFR 11.35, I got an AFR of 11.1. When the rpm changed to 5140, the AFR changed to 12.6. All other readings stayed the same. Below is a copy of the appropriate part of my VE table. Maybe you can see something here.

MAP
90 95 100
RPM 4800 126.83 134.11 141.63
5200 126.58 134.71 141.63
5600 122.13 128.26 136.92

[Tordne]

Can you attach the log? I just pasted your values and they don't appear to be peaky.

[tgeers]

Tordne,
Here is my log file.
Tony

[Tordne]

Have you managed to hit these cells prior to your time at the track? Perhaps its just a case of applying the average BENS to the VE table and repeating.

As much as you might try the BENS will never read a solid 1.00 in any cell that you tune. There will always be some variance, given that you have 8 cylinders which are not likely to be "exactly" the same.

In my case I consider that my VE Table is pretty damn close to spot on - as it should be after messing with it so long :). My BEN factors in WOT land still range from 0.98 to 1.02, which is basically a pretty tight range.

What do your BENS look like under regular driving conditions?