1MeanZ

iTrader: (9)

I'm new to tuning, and I've been digging for information. I've read and learned quite a bit so far and I'm reasonably comfortable tuning on my car and I have to say i've got it about 85% where I want it.

In my searches I've seen all kinds of debate about how to properly tune a MAF car, here is a brief breakdown of the tuning approaches.
1. leave MAF table and Scalars alone. Tune with injector constant and battery voltage vs pulsewidth. This is the least invasive way to tune that wont mess up the LV8 calculations. this is Grumpy's suggestion.
2. tune with the MAF tables but leave the scalars alone. adjust the injector constant to what it should be.
3. MAF tables and Scalars are free game as long as you have a wideband and know what you are doing.

I've taken step 3 thus far and I'm having pretty good luck. I met up with doc and he helped me get my initial grasp on these things, his help has been much appreciated.

I wanted to see how the factory dealt with this issue so I decided to compare the Corvette L98 .bin to the LB9 Camaro .bin. The MAFs are the same, but each engine has different injectors so I thought this would be a good representation of what many of us have done with increased displacement and larger injectors.

In comparing the APYP.bin and the ANYX.bin I found that the factory seems to have modified the MAF tables AND Scalars. I need to do more studying to see what % the factory moved the scalars up vs the added 45cid, but I must also remember the different injector sizes.

I just thought this stuff was interesting. I'm going to continue to compare these .bins and see what other differences there are, and determine what % difference there is. Just wanted to throw this out there and open it up for dicsussion. I hadn't found in my searches where anyone else had done this, so it might be a little bit of new light on a very old debate.

Rebuildman

I am by no means an efficent tuner. I have tuned 4 different motors so far with the chip burn and custom bin. My best results by far have come via your 3rd method, but using WB and open loop. The injector constant change makes a broad overall change that suits me well for getting close to the A/F ratio I want. I also find some injectors are not what they claim to be as far as flow is concerned.
My biggest surprise so far doing the tuning is the results that less timing has on the motors, I always was under the impression more is better, has not been the case for me. Less is best!

Guest

Step 1 was thankfully later revised.

2 is for minor changes.

3 is for the rest of us. What you can do is plot the points in a chart using Excel or the like. If you use step 2 you will find out you'll end up with a bunch of plateaus at the end of each table. You want something more similar to a steady curve, adjusted of course to what the car is telling you it wants. Its not linear.

I'm not really surprised at different numbers from GM. They did do some amount of tuning rather than just spitting out something close and saying ok.

doc

1MeanZ: That is a great idea to compare those two bin file! You keep going like this and you can help me get my car into the 11s.

I was using method #2 along with fine tuning by changing the fuel pressure w/o going back and changing the fuel injector constant to match. Changing the fuel pressure at the dragstrip was a good way to zero in on best trap speeds.

However, with the advent of my MEGA MAF, I am using method #3. There was no way to tune the ECM w/o changing the MAF table scalars.

Orr89RocZ

iTrader: (20)

give the motor what it wants and keep the MAF tables/scalars in check so that the curve is smooth and things should work out ok

thats the approach i'm gonna take on my 383 once its running

pretty much start with step 2 and work into 3 if i need that for part throttle stuff. WOT tuning will always more than likely be PE mode and maxed out 255 gm/s MAF sensor

1MeanZ

iTrader: (9)

thats basically what I've done as well. I had to move the scalar for table #1 up just a bit, all the rest of the scalars have been able to remain because I've had room to adjust the MAF tables. A little bit off topic, but I just did some more tuning last night, and I can't believe how smooth I've gotten this thing to idle. It has the LPE 219 cam, which is not large by any means but it always used to idle with some attitude. Now that I'm getting it tuned correctly, I'm debating lowering the idle speed, its only at 900 right now. It idles near stock now. I'm going to start telling people it is a stock 305...

antman89iroc

Injector constant fudging is fine when you have big, across the board lean/rich issues. I always seem to end up back at the "correct" IC after the adjustments described below.

I use battery voltage more for idle tuning. For example; when the electric fans turn on and it goes rich/lean. Raise the number at a particular voltage richens (slightly) the mixture.

I left the scalars/tables alone at first cause I didn't really know how to use/modify them. Now it is THE way I tune cruise A/F. When I datalog I look at the maf gm/sec at a specific LV8 where it's rich/lean via the blm's. Then, I go back to the table at that gm/sec and adjust rich/lean. BTW, raising the gm/sec (at a maf volt) richens the mix. Conversly lowering the gm/sec leans the mix. So, if the blm at say 35 gm/sec is 132 (lean) I would go to table 2 and see at what voltage the table was around 35 and raise it slightly to richen the mix. It seems that small adjustments to the tables make a lot of differance. Just make sure to "blend" the values near the adjustment. Sometimes (esp. in the first table) you have to "estimate" the amount to change. Or, the exact value isn't in the table and you have to adjust the cells above and below it. Trial and error with lots of datalogging will guide you here.

Also, with modified maf meters, it requires all the scalars to be modified. With my screens and fins removed, I adjusted the scalars by 10% (scalar * 1.1). This adjusted all the maf tables accordingly. Then, I went back and "tweeked" the maf tables at certian points by the above method.