VTC_WS6

iTrader: (9)

I finally got around to dyno'ing my TA yesterday and I took my laptop along to do a little tinkering. What caught my attention more than anything esle however was the very first pass, in which my A/F's were in the very high 13's and in a few spots even touched 14's! Call me crazy, but that seems ridicluously lean for a healthy motor.

Has anybody esle dyno'd a bolt-on TA and gotten such lean A/F's? Hoping this isn't something unique to my car..

FWIW, I ended up making the best power with a 12.8-13.1 AFR and 24* top timing, picked up 8whp and 11wtq over the base run

SSpdDmon

iTrader: (10)

Yes, I've heard people discussing lean issues with '00 f-bodies. My guess is it's worse on the ram air Pontiacs. I think there was a TSB that GM sent out regarding the issue too. Don't know if anyone has a link to it or not.

99SS-T

iTrader: (5)

So long as it isnt a forced induction or nitrous engine I was under the impression that that was regular.


John

mtnbkr81

iTrader: (1)

I had the same problem when i first dynoed my 01 SS. I hooked up the laptop to the car and found that the MAF sensor was doin some crazy stuff. The car was also pinging a great deal. I ended up changing out the MAF sensor and the pinging went away, but i haven't hooked up the laptop to it since to see what it's doing.

Mark99Hawk

iTrader: (4)

I had the same thing on my '99 Firehawk. The stock tune was VERY lean with the only mods being a lid and the SLP dual/dual exhaust.

Mark

soundengineer

iTrader: (16)

its because the MAF is wrong from the factory....
every F-body I have tuned..the MAF has needed recalibration to nake it right...

remember one thing...
just cause you are seeing it on the histogram does not mean its lean right now..
the FUEL TRIMS are LEARNED...
meaning it is still running 14.62857 (stoich)
all teh histogram means is that it is currently adding or subtracting to your VE tables or adding a percentage to that section of the MAF Airflow vs HZ chart to get stoich....

so you are not running lean right noiw..but you were at one time and it has learned that out...
the thing you need to worry about is WOT.......its only following the #'s exactly as they are...+ the PE multiplier...
more than likely you are safe...but not ideal...
in technical terms you could be as lean as 18:1 and still be at 14.4 with the stock multiplier of 1.250....


basically...you need a Tune and a MAF recalibration...
and ever vehicle is different..otherwise I would just send you my MAF chart....

heres a worksheet to get your MAF corrected after you do VE in SD


https://ls1tech.com/forums/showthrea...5&page=1&pp=20

soundengineer

iTrader: (16)

oh yeah...and ANY mod you make...regardless of how small it seems to you and me.... can really throw thinsg out of whack

Y2K SS

iTrader: (1)

The 3 stock cars I ran logs on recently were all lean also. Sound hit it on the head.

soundengineer

iTrader: (16)

basically GM did their tests on the MAF...and set it to be in a general "Range" to fit most cars pretty close...
each car is going to have a certain "Slop Factor" in the parts...which also comes into play with the tune...and slop was designed in with the tune as well...after all, they were trying to keep the cost down some...
so in this generalizing, they just got close...but not exact...
some cars actually show rich...some show lean...some show right on...
most are close enough that with a little fine tuning you can turn an ordinary #'s car into a slight freak...with just a simple tune and correction....