heres a good discussion I found on hptuners site if anyone is interested
http://www.hptuners.com/forum/YaBB.p...07;start=60#73

 

If Txhorns or WS6snakeater are in the thread, it's worth a read. They usually have something interesting to say, I think at least.

Keep us updated on your maf cal. Try putting the stock table back in. I'm wondering if this will send you more negative or bring your back closer to 0.

 

Ive been talking with TXhorns and this is an email he sent me describing how to nail down the maf. Its makes so much sense I cant believe I didnt think of just doing like this. Im gonna try it today its gonna take a while but hell Im unemployed and got nothin else to do.

"The MAF and VE tables are completely independent of each other. Contrary to what a lot of people think, I honest don't believe the VE tables and MAF work "together" when in MAF mode. I've never had much success tweaking the VE table and getting good results with the MAF enabled, which leads my to believe that it operates only as a check for the MAF. Like if the MAF reading is waaaay off from the VE reading then the PCM will default to the VE table for airflow.

Each table is a separate airflow function and we taylor the MAF to behave like the VE table since we are able to tune the VE table with greater ease. Now in open loop the VE table makes a huge difference as well so it is important to tune it out. But I've tuned cars completely off the MAF before and not touched the VE, and had positive results.

OK so you're driving along and generally I bet you see your negative trimming sort of isolated to a specific area right? What you want to do is sample around the boundaries of this area (make the blue cursor move around the outline of the affected area) and keep an eye on the MAF gauge in the display. Right when you get to the point that your trims will switch from being ok, to way negative (it should be almost clear as night and day where the line is on the MAP rows) remember what MAF reading you see. Like I generally round to a nearest .25 So like 3.5 or 2.25 or 2.75 for example. At a certain frequency range, if your fueling is disrupted, it can trim away at any instance that particular frequency is hit. What i mean by this is especially at low engine speeds, 3 lb/min on the MAF can be made in 1st, 2nd, 3rd, 4th, 5th, or 6th at XX mph, at XX TPS, at XX MAP. See how may variables we have here that can all make up the same thing? This is why you will hunt for a certain MAF range where the fueling is crappy. Like, from 2500 HZ all the way up to maybe 3250 or something like could be the cause of all your stupid trimming you see. It's a small range, but even if you only reduced it by 5% it may make a HUGE difference. The values on the MAF table on the low end are so small but so critical. You see #s like 11 and 10.56 and 14.20 and such. Well, 1% of all those #s is like .1 and .14 and such. So even just by changing low end MAF values by .5 can make a big big difference."

 

Here is the first email I hope he doesnt mind me sharing his knowledge, there is so much usefull stuff in these 2 Ive read them several times. Thanks for all the help TX


"I never got any rich codes but I've come to learn that SD airmass calculations are often more incorrect than they are. Now over an average time frame, they will suffice, but dynamic airflow is very sensitive and fuzzy at low rpms. So I take the initial MAF calibration as a base point. From there, let your car fully learn all those negative trims and what not, once that happens, go logging for a bit and keep an eye on MAF (lb/min) and where your trims are occurring. Like if you notice the negatives only pop up from 3.00 lb/min and below, then go to your MAF table, take 3.00 times 7.54 to convert to g/sec. And that should be 22.62 right? So find the closest MAF cell that reads 22.62 and highlight it, including everything below it and for every 1 trim it is off, scale the MAF by .75%

Meaning if you have a negative 10 trim, multiply the MAF are it is occurring in by .925 (7.5% decrease). Now you will have to use common sense here. If most of the trims in the affected area are let's say negative 5, but you have a few negative 8s, go with the more popuar discrepancy. This will take a little trial and error but once you do it a few times, you get really good at tweaking the MAF curve around. The MAF calibration supra and I worked on is very good for part throttle and higher loads like WOT, it can be dead on for WOT. But low rpms are a funny thing, the calibration ends up being pretty close, but down low you gotta be EXACT...

I think having an internally modified car also fudges things up a bit, I know I've always had to do more tweaking on cams than on bolt on cars! But then again there's no real necessity for a bolt on car to do SD tuning.. lol"

 

finally got the solution down and wow is it worth it

Ive outlined the steps on tuning the maf in a post over in the pcm section very easy to do

https://ls1tech.com/forums/showthread.php?t=336353

 

Good info...

Glad you got it worked out.

 

the more the computer learns the trim levels (even though they are below 3% error)the better this maf tuning gets the throttle response is just silky and its so smooth and powerful it feels smoother than a stock truck plus 120 hp I think even a bolt on engine cuold benefit from this, it feels like im driving a sports car