Playing with EFILive V5.26 through ATAP on an 02 Z28 M6. Car is stock, except for Holley Filter and LS1 lid. Testing Nitto DR at HRP we are seeing AFR of 11.1. PCM goes to open loop at launch, AFR 11.1-11.3.
IAT started at 117 gradually dropping to 69.8 at 1/4 mile.
Air temp was around 60, with 90% humidity.

I was expecting AFR around 12.5-12.7?
Also, AFR was 14.6 before run, while idling, 14.3 on return road, so it looks like the recorded values were accurate.

 

EFILive (or any other scan tool) cannot display the actual AFR. What EFILive is reporting is the commanded AFR. You would need a wideband sensor to determine the actual AFR.

Tim

 

Tim,
This is my first foray into EFI, and I would like to know more. I would like to learn more about the theory and operation of the engine control system on my LS1. Other than this forum and OBDII.com, can you recommend any other references for the layman. I think I will use an experienced tuner if I modify my car, because the expense would probably be less then trial and error (especially with my luck!). I just want to know what all that equipment is doing.

 

My A/F ratio on my near stock (lid,cutout) hovers around 11:1 - it was a bit richer before the cutout. I know this is from 2 diff wideband dyno sessions.
These things run way rich stock @ WOT...probably because they new people would mod the cars and didn't want them running lean. <img border="0" alt="[evil]" title="" src="graemlins/gr_devil.gif" />
I'd say your EF Live isn't too far off.

http://www.netlinkapplications.com/a...es/dyno2lg.jpg <img src="http://www.netlinkapplications.com/aaron/images/dyno2lg.jpg" alt=" - " />

 

From everything I've read you look rich. I believe the numbers you said you expected are closer to where you should be (12s). Below that and you probably look like Eddie Hill used to look on the start line at HRP, raw fuel spitting out of the headers. It's impressive, but when the green comes on can you burn all that petro?

 

In theory max power is at 12.6:1 Air/Fuel ratio <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />

 

Actually 12.8-1 for most tq
and 13.1-1 for hp

<img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />

some guy at ls1.com was telling people that 12.3 was the best <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />

On a forced induction or Nitrous car you want something a little more rich for safty but on a NA motor you go by those #'s

 

The books that I have read agree with Dave.

 

The best A/F ratio for your car is the ratio that produces the most power on a dyno. You will get lots of opinions because it's different on every setup. Without a dyno 12.5 is as good as any.

 

You tend to run a bit leaner on the track than on the dyno, so I would run a couple tenths fat on the dyno tune.