95 trans am lt1 diagnosing poor running/ running lean

**zoomo** · 10-17-2014

Ha I suppose I could have picked a better description. In comparison to how it was this was before running lean and like crap. Been working on a tune since last night. Added in steveos timing. Seems to be closer to what I need . as I'm getting some spark knock at take off. According to sensor at least. Also changed one if the maf tables. Not sure exactly how those work yet but somewhere along the line one was turned up to more rich I believe. Set it back to stock. Anyway I'll let y'all know more tonight. Thanks as always for the help and critiscm ha

**steveo** · 10-17-2014

leave the maf tables alone until you understand how to tune it properly

what you want to do is identify some points where the BLMS (long term trims) are particularly lower or higher than 128 at a constant throttle position. start by tuning stuff under 120 or over 135. make sure these values are from a warmed up car that has been driven for a little bit. then find the AFGS airflows where the BLM is off. lower than 128, you need to REMOVE fuel. higher than 128, you have to ADD fuel.

then go into the MAF table, find that AFGS, and raise or lower the value with multiplication. do it gradually. take the value times 1.05 for 5% more fuel, or 0.95 for 5% less fuel. this will be a small enough amount where you wont hurt anything.

after you've done that one cell, you have to smooth the adjacent cells (using the graph works well) so transitions are smooth. you want to build yourself a curve, not a straight line.

once you've done a few of these points and got it smooth again, stop, flash it, log again.

this is a caveman method compared to doing it mathematically over a very long run using things like tunerpro history tables or hand-hacked tools that i use, but it works

if you find yourself moving maf cells more than 10 or 15 percent, and the curve naturally starts to look weird, stop tuning it. you probably have some other problem.....

**zoomo** · 10-18-2014

please tell me if im understanding correct. The number on the right of the maf table is my engine air flow? im trying to understand how to adjust it. i cant find anything to relate the hz measurement to, so im assuming the other measurement is engine airflow ha

Edit put about 100 miles on it tonight. at about 40 i installed a new airfilter. may sound strange, but it was old and raggedy and it seems to have helped the blms. maybe its just driving and learning though. anyway, its holding pretty steady at about 115-117 when cruising, with slight fluctuations depending on the rpm. but at idle im running pretty bad split with about 118 and 134. it seems to be running well, and the blms have stopped jumping as much. i would load the logs but they are too long. thanks in advance

**steveo** · 10-18-2014

with a maf like that, anything in the intake tract that affects HOW the air flows, including blockage in the air filter, can affect calibration a bit.

The number on the right of the maf table is my engine air flow?

you never have knowledge of "the number on the left" which is hz or whatever. all you're doing is taking an airflow value which is IN ERROR at that particular point, and altering it slightly.

**zoomo** · 10-18-2014

drove a lot more today. the numbers seem to be about where they were last night.The blms are low, somewhere between 114 118 when steady throttle throughout the rpm range. if i accelerate of course it changes. My question is, would i be wrong in multiplying all three of the maf graphs by 0.95 to lower the fuel across the board? or where is the stopping point. i understand you say make it smooth, but is that in one of the graphs, or all three. because i see how it is smooth across all three. thanks in advance for everything.

**steveo** · 10-18-2014

it actually IS one big table.

i had to split it into three (some software splits into 4) just because tunerpro's 2D graphing zoom ability sucks, and it doesn't auto-size large 2D tables very well.

so yes, it has to be smooth across all three.

My question is, would i be wrong in multiplying all three of the maf graphs by 0.95 to lower the fuel across the board?

that'll be a good starting point.

i would still hesistate to multiply the 3rd table by that much, for safety. maybe just multiply the lowest two tables by 0.95 and the highest one by 0.98, since i doubt you have any real evidence of how your high airflow is doing.

if you can get your trims up to 124 or so on average, i'd just leave it there, and let closed loop lean it out that bit extra.

**zoomo** · 10-19-2014

well i took it on about a 1.5 hour journey each way tonight. seems the more i drive it , the closer it gets, now it hangs out around 117 120. I havent tried adjusting any maf tables yet. I was thinking maybe i should wait until i can get it on the dyno or get a wideband a/f set up. is it normal to have to lean it out for a larger cam slightly? or are you actually leaning it out, or just telling the computer that its getting more air? i can only find one tune for a car set up like mine online, and the maf ables are not changed in that tune, but who knows how exact it is.. my injectors are stock. and my cam is a 226/232 or something like that ha

**steveo** · 10-19-2014

yeah, it's normal. maf calibration at low rpm is really sketchy with a larger cam, the air pulses back and forth instead of straight in, so it'll read kinda rich.

**zoomo** · 10-19-2014

sorry i know its a huge log. mostly just cruising home but theres a few take offs. also the blm split at closed throttle seems to be the worst. but i raised the corrcl and i think thats why. maybe i need to lower it again, it seemed to be better at closed throttle that way. im also going to adjust the maf table as you suggested for the next flash. hopefully this looks more like it should, thanks for taking a look at it if you do

**zoomo** · 10-19-2014

sorry to double post but im confuused about the maf tuning and im having a hard time finding information about it, but maybe im just searching for the wrong things. anyway, i did some highway driving today at higher rpm trying to see how the blm looks. even if im running at say 3000-3500 rpm for a few minutes on the highway with steady throttle im still showing 117 120 and sometimes lower. is this still normal with the bigger cam? im paused on tuning right now, i dont want to lean anything out if im going in the wrong direction,but i will continue if this is fairly normal. according to the narrowband running off of the stock 02 it shows its lean to stoich and rich when accelerating.

**zoomo** · 10-21-2014

OK guys help me out one more time. Got it on the dyno today. Seems decent. Power could be a little better but that's normal ha. Running lean though not much. I expected it to be rich if anything. Though it does seem to be a corrections issue. Notice the rich AF ratio. That was with the maf unplugged. Posting from my phone so sorry for errors. Let me know what you think and thanks as always

**steveo** · 10-21-2014

that isn't rich, it's VERY lean for wide open throttle. you're hitting 15:1 there, you need to be around 13:1.

**zoomo** · 10-21-2014

Sorry for the blurry pictures. Maf plugged in running 15-1 up to 4000rpm then drops down to 13.5-1 by 5000 rpm. Maf unplugged running 13.75-1 and dropping to 12.75-1 by 5000 rpm

**steveo** · 10-21-2014

your maf tables must be way off or you have a leak in the intake elbow, or the maf is dead. theres no way itll nail a better wot afr with stock ve tables better than a maf.

**zoomo** · 10-21-2014

So I tried adding 10% to the maf table all the way across. Did lower the AF but only about .5 I'm confused though I was understanding that with the blms reading low I should be removing fuel ?