I just installed an Innovate LM-1 and an Apexi V-AFC II. I figured that I would try to lean things out a bit to free up some power. I was a little confused when I did a baseline datalog. My fuel pressure was 43 psi and I didn't do any air correction with the vafc. Any thoughts on why it's already so lean??

This is from about 2k-6.5k rpm in 2nd gear.

 

You cant get an accurate reading of a/f on a short gear like 2nd. You have to go to 3rd gear at least so it puts more load on it. The lower loads of the shorter gears makes for a leaner a/f reading (that you are seeing). That is not your real a/f. Get a 3rd gear log, THEN you have something more accurate to work with.

 

I thought about logging a higher gear and I definitely will now that you've mentioned it, but I was expecting the AFR to be somewhere between 10.5 and 12. Would logging a 2nd gear vs. 3rd gear really show that much of a variation?

What do you think about logging 2nd gear going up a steep hill? I just don't like the idea of doing multiple 3rd gear pulls on the street.

 

There shouldn't be that much of a variation from gear to gear with an n/a motor. What's the indicated AFR at idle?

 

That's what I thought. Idle AFR is ~14.7, right where it should be, imo.

 

My first step would be to bypass the AFC.

 

I was thinking about trying that.

Is there any difference between 1in 1out and 4in 4out?

 

exhaust leak

do you still have all 3 cats you will read alittle leaner/richer depending on the sensor location

did you make sure the corrections on the controller is zero'd out

 

Pre-o2 exhaust leak causes a rich a/f during closed loop conditions. His a/f is lean during an open loop condition.

 

I was referring to a possibly leak near the wo2 which could make it read lean due to the extra air

also a intake leak could cause the lean reading. it happened to me when a vac cap starting to go bad I used to plug the manifold, it was weird cause during light throttle and idle the a/f would be fine but under 80%-wot it would read lean. the only difference in his graph and mine was I would spike really bad around 4k

 

Afaik, I don't have any exhaust leaks. I only have one cat (it's a VE) and the WBo2 sensor is located slightly upstream in the factory o2 sensor location. The corrections were definitely zero'd out and it was set to 4in 4out.

I didn't mention that this pull was done going down a slight hill which is probably why it's so lean (along with the fact that it was in 2nd gear).

I did some more tinkering and made a few runs. My last run was done in 2nd gear, going up a steep hill, with 1% more fuel. The AFR was between 12.5 and 13 from 4k to 6.5k rpm. This is better, but it's still alot leaner than I was expecting.

 

I was wondering if I have an IM leak. I really don't think that I have one because it idles smooth and I don't hear any leaks, but maybe I'll look into it a little more.

 

mine would whistle like a sc which turned out to be a good thing and allowed me to find it really fast