2000 LS1"
Xspower long tube headers with cats
LS6 intake manifold
Vararam
Borla catback
Powerbond udp 25%
fuel filter (oem)maybe 18months old
fuel pump (LPE stock replacement)
201k miles original unopened

Part throttle, cruise, and idle a/f ratio is 14.8-15.6
WOT is 15.9-16.2 on my aem wideband.
WOT on a dynojet is (take a look below)
I don't have any exhaust leaks and the maf couplers are tight.
after doing a wot pull on a closed road and letting off the gas the a/f went to 11.2-12.3 then back to 14.8-15.6.
The car does not hesitate, stall or crank long. Pulls clean from what my butt can feel. I do have a mail order tune, but Im not sure if anything else is causing the a/f to be so lean. I get no cel's.

Anyone think I may have something else going on with the car other than the mail order tune causing the lean a/f readings. Thanks

 

Looks like you need another tune because thats big time lean

 

Don't expect it to last long if you keep beating on it with that air to fuel ratio....

 

thanks for the replies, was thinking it wouldn't last this long with the mileage, but since it is Id like to keep it running its best. I will not be beating on it till I can get the tune reworked. Just wondered if anything might be worn out due to age like valve springs or maybe a fuel pressure regulator, but I doubt that also. Is it possible I got a 28lb injector tune but only using 26lber's.

 

It could be the MAF. When MAFs go bad, they don't fail outright, they report low. If you get a chance to try it again and you have a buddy who will loan you a MAF...

 

Wouldn't I get a cel if it was out of range, shorted, or open?

 

I agree with Frost. Probly a bad mass air. They will never throw an engine light.

 

got the car back yesterday, the mail order tune I had just didn't pan out for me. **non-sponsor** I haven't been back to the dyno yet, but will post a comparison of my car between a mail order tune and a local tuner street tuned. I have to say, even though its cooler outside the car feels good in all gears now. The part throttle in low gears feel way better. I hope to at least make 345-355 whp. The A/F ratio wot now is @12.8-13.1 on the street where it should be. Nothing is wrong with the car no cel's or nothing. The injector duty cycle is at 86%. The changes were editing the maf table,enabling the stft's(was disabled), and overall about 20% fuel added in the PE area I think. I forgot exactly what he said but something similiar. Probably be another 2-3 weeks before I dyno again.

 

It's easy to tune around a failing MAF if it's not recognized. I'm not saying that happened, but, as I said they report low. If you had to have 20% added, that's what I was referring to though. A mail order tuner would go out of business in no time if he sent out a bunch of 20% off files!

If it was that far out, the car should really pick up a bunch for ya.

 

Wow

BTW, you can't pimp non-sponsor shops here so do not post his email address. THX

 

Sorry folks, didn't read all the rules. planning on going to the dyno tonight!

 

This is still not a full dyno/street tune, but Im going to have to keep this tune for a good while. I feel this should be way safer than the previous. numbers= 355whp359wtq. It was about 45-50 degrees this evening.

 

It's still 14-15:1 up to 3K RPMs and it's 13.5-14:1 through the upper RPMs.

 

You noticed that too? LOL

 

i dunno, my wideband on the street didn't go above 13.2

 

I'm still betting on the MAF.

 

I have a stock GM MAF I'll sell ya dirt cheap from my old 346 setup. 2 1/2 years old and about 30k on it....