Thee NYPOC Lounge

[TRWeiss1]

I bet you are, Ant...I bet you are.

When you going to install it?

[Domino81]

Already installed and trying to figure out the formula for calibrating MAF... this is a pretty steep learning curve for me and I'm getting pretty upset. Like, it just doesn't makes sense. It's easier now that I have something to apply it to, but making the adjustments... the how, what, why... where... I'm getting really frustrated and I'm only at the beginning.

[TRWeiss1]

It can be overwhelming if you've never done tuning before, Ant. Don't give up. I know I don't have to tell you, but there is a wealth of information online about the AccessPort. It'll come easier once you learn the basics, and the more you play with it.

I literally know NOTHING about the AP, but for tuning I generally do the following. First, you start with a "base" tune (either preloaded, or sent to you from a member w/ a similar setup), and start driving around while being light on the throttle. Watch AFRs closely, then start to get on it so you get into a small amount of boost. You gradually work your way up while getting into boost and adjusting ONLY fuel, while maintaining a very safe timing map. If you encounter any backfiring/bucking/etc, check what your AFRs are, and adjust them accordingly.

Once you've gained good drivability under light, moderate, and full throttle with no backfiring and safe AFRs, you begin to adjust timing. This is the tricky part....You'll [generally] make the most power at the highest advance BTDC just before you start encountering detonation. Listen carefully for knock, and pull your plugs during this stage to read them. I'm sure you'll find a billion posts of what others are running for their timing curve. But yeah, start getting a little more aggressive on the timing, then a little more, all the while watching your AFRs and listening CLOSELY for detonation/reading your spark plugs.

The best tuning will obviously come from being on a dyno, but for the street the best you can hope for is safe AFRs and the butt dyno. After you're happy (and have gained a few more HP from the butt dyno) with your timing, you'll then go back and tune fuel once more. Idk what the target AFR to shoot for under boost is for that particular car, but I'm sure you do. I'm not familiar with the direct injection motors. I know for my FD it likes to be super rich, as in 11.5 or so. I used to tune for ~12.2 with my 2nd gen Probe.

[KLDE Wagon]

I tuned Andy's to 11.9. This was the number another guy gave him that tuned his car a lot I guess. It worked well... 286 on the first run. A little timing, a little more fuel, and we hit 306. If the accessport is the same for the MS3 as Subarus then there will be plenty of base maps around. Just find the one that is most similar to your mods. Personally, I'd hold off on doing ANYTHING with it till you get your fuel pump internals... There's a good chance that any tuning you do will completely change with the new pump. It also wouldn't hurt to do a tune up so everything is fresh before you start... Fuel filter, air filter, plugs...



Jeremy

P.S. You won't be able to read your plugs instantly after you drive it once... You gotta drive it about 1000 miles minimum. Detonation will leave black specks, lean condition will deform the end of the plug (too hot, not enough fuel to keep it cool), stoich will have a bit of a brown glaze on the plug.

[Domino81]

I have a base map installed, but the formula for calibration doesn't make sense to me...

Chapter 4: Calibrating your MAF
Okay, you’ve made it this far. By now you should understand the basics of a turbocharged engine, you
should have made several logs to gauge your setup, and you’ve installed Access Tune Racer, or ATR.
This will be your first tuning exercise, and it will take some time, which is good; you’ll have a chance to
study.
Calibrating your MAF is somewhat tedious and time‐consuming, but it is vital that it be done correctly,
especially if you have done any type of intake modifications. The MAF comes pretty well‐calibrated
from the factory, so I wouldn’t expect a stock vehicle to need it, but even then you might benefit from
going through this exercise. The reason it is critical is because down the road, when you are
commanding leaner AFR’s in open loop, these commands need to be spot on. The ECU is smart, but it
can only do as well as its sensors and if they are feeding it good information. Calibrating your MAF will
make the ECU’s commands for air and fuel targeting safe within the first order of magnitude, and highly
performing in the second.
To begin with, you may as well examine your LTFT’s to see how much work you have to do. The way I
like to do this informally is to turn on my AP and live monitor the LTFT section. Then just drive to get
some groceries, or whatever shit you like to do on a Saturday. Now is a good time to take the wife,
girlfriend, or kids, as you won’t be hitting it hard, but you do want to go through plenty of city traffic and
don’t be afraid to drive right up that onramp. While all this is going on, your AP will let you know the
lowest and highest thresholds of LTFT. If you’re like most people who show up on the boards needing
help, you’ve probably already flashed a stage 1 map, and now your LTFT’s will be in the range of ‐15/15,
or even a touch worse.
Cobb recommends that you calibrate your MAF to be within ‐8/8. From now on, I will refer to this as an
absolute value (an expression of magnitude independent of being positive or negative), or abs(8).
Personally, I think that even abs(8) is rather imprecise for a good tune. I try to be within abs(2) at all
times, though weather, A/C, and simple entropy can thwart you. You should definitely tune the
calibration to within abs(4) across the entire MAF range if you want to feel successful about this
exercise, in my opinion.
Ok, as for the actual calibration, this is the technique as far as the driving. Take her out to a nice quiet
road far away from muggles4 (non‐performance drivers), and set your AP to live monitor your Mass
Airflow in grams/second while logging. At idle, this value should be at around 3. Get into 2nd gear going
rather slow, about 2,000 RPM. What you need to do now is increase your acceleration smoothly and
slowly through the whole power band while you watch the g/s readout. You want to hit numbers
through the whole spectrum, from 5 all the way up to around 130 g/s. It will take some practice to get
this right; it will be the slowest way you ever get close to redline. Do this three times, and you will have
captured your data.

---------- Post added at 06:38 PM ---------- Previous post was at 06:36 PM ----------

It ought to look something like this:
Long
Term FT
(%)
MAF
Voltage
(V)
Mass
Airflow
(g/s)
‐4.06 1.3 3.51
‐4.06 1.31 3.51
‐4.06 1.27 3.66
‐4.06 1.23 3.26
‐4.06 1.23 2.98
‐4.06 1.54 3.02
‐4.06 1.23 4.06
‐4.06 1.3 2.94
‐4.06 1.3 3.7
‐4.06 1.29 3.75
‐4.06 1.3 3.42
‐4.06 1.3 3.51
‐4.06 1.3 3.56
‐4.06 1.32 3.51
‐0.16 1.54 3.96
‐0.16 1.67 6.35
‐0.16 1.71 7.89
‐0.16 1.7 8.79
‐0.16 1.79 8.45
‐0.16 1.81 10.57
‐0.16 1.85 11.07
‐0.16 1.95 11.8
‐0.16 2.01 13.53
‐0.16 2.11 14.89
‐0.16 2.09 17.6
‐0.16 2.1 17.22
‐0.16 2.07 17.45
‐0.16 2.07 17.15
‐0.16 2.08 16.67
‐0.16 2.07 17.22
‐0.16 2.08 17
‐0.16 2.1 16.93
‐0.16 2.19 17.37
‐0.16 2.24 20.54
‐0.16 2.24 21.87
‐0.16 2.23 22.88
‐0.16 2.25 22.68
‐0.16 2.25 23.28
18 | P a g e
Copyright © 2011. Abilor.Tuning@gmail.com
‐0.16 2.24 23.08
‐0.16 2.24 22.48
‐0.16 2.27 23.28
‐0.16 2.3 24.97
‐0.16 2.31 22.48
‐0.16 2.41 24.97
1.4 2.41 28.9
1.4 2.49 28.7
1.4 2.52 31.98
1.4 2.51 33.31
1.4 2.6 32.87
1.4 2.62 36.79
1.4 2.64 38
1.4 2.69 37.75
1.4 2.8 41.29
1.4 2.77 45.89
1.4 2.8 45.61
1.4 2.83 48.12
1.4 2.87 49.82
1.4 2.9 53
1.4 3.04 54.78
1.4 3.11 69.84
1.4 3.28 82.87
1.4 3.29 94.8
1.4 3.3 96.19
1.4 3.36 96.65
1.4 3.42 101.34
1.4 3.47 108.08
1.4 3.48 114.06
1.4 3.51 114.58
1.4 3.54 116.11
1.4 3.55 120.81
1.4 3.49 121.86
1.4 3.51 115.6
1.4 3.73 118.7
1.4 3.74 143.55
1.4 3.99 143.55
1.4 4.04 160.89
1.4 2.85 185.55
1.4 2.08 167.69

You’ll notice right away that I cleaned up the workbook, and omitted all the other values except for
LTFT, Mass Airflow, and MAF voltage. You don’t need to do this, or if you do want to be hyper‐anal, you
really don’t need MAF voltage either. In any case, you can see in this run that I gradually and linearly
increased my Mass Airflow along a smooth spectrum of values. You will also notice that I highlighted
two sections. These are breakpoint range adjustments, and you will want to tattoo the following
schema onto your brain:
Mass Airflow
Breakpoint Ranges
0 – 5.7 g/s
5.7 – 18 g/s
18 ‐ 30 g/s
30 – 77 g/s
77 – max g/s
Table 2: Mass Airflow Breakpoint Ranges
So here’s how this works. Those breakpoints represent zones in which the ECU tends to break up it’s
learning of LTFT patterns. You want to look for solid blocks of trim adjustments that the ECU has made
within those ranges. With my log above, you can see that the ECU has an LTFT adjustment of ‐4.06
within the first range of 0 – 5.7 g/s. What does this mean? It means that over time, the LTFT is pulling
4.06% of the fuel out of the injection stream in order to hit its targeted AFR. Similarly, it is adding 1.4%
more fuel (1.4, the green block) in the roughly 30 – 77 and 77 and beyond ranges. When you first are
starting out on this calibration, you will likely see a wide distribution of values in each of the 5 ranges.
So what now? Well, first you should check all three of your logs (you did make three, right?) and see if
the trends are consistent. If so, you should settle on the LTFT adjustment block within most of one of
the above ranges as what you need to calibrate. What I mean is that for my 0 – 5.7 g/s range above, the
ECU is pulling 4.06% of the fuel for the majority of the range, therefore I want to calibrate my MAF to
pull 4.06% of the fuel from that range all the time, so my ECU won’t have to adjust for it on the fly (not
as much, anyway. To do this, I will need to do some math first. I want to calculate the adjustment
based on the following formula:
MAF Calibration = (100 +/‐ LTFT Adjustment) / 100
In this case, it would be 100 – 0.0406, which is 0.9594.
Great! Now what?

My LTFT's after driving a bit today were at -7.96. All 5 runs were consistent. Someone mentioned I may need to drive a bit more. 50-100 miles; I think I have 30. I may take a trip to Tully tonight.

[KLDE Wagon]

Was your lift +7.96 or -7.96 across the board? That guy's seemed to fluctuate quite a bit... It seems you need to adjust each range.

So, 100 + 7.96 = 107.96 divided by 100 is 1.0793

Or...

100 - 7.96 = 92.04 divided by 100 is 0.9204

One of those numbers will be your adjustments... Depending if it was +7.96 or -7.96.



Jeremy

[Domino81]

I'm taking a trip to Tully in hopes my ltft are a little more normal.

[Domino81]

Paid for my tune a few minutes ago. As soon as it's done I want to DYNO. When are we headed back to Daves?

[TRWeiss1]

Good question. Shit though, if the weather holds out we could literally go down just about ANY TIME.

[KLDE Wagon]

Agreed...



Jeremy

[Domino81]

300 whp or bust.

[TRWeiss1]

Definitely.

Hey Hiney Ho, do you think you'd be able to come take a look at my setup once I get my manifold/turbo on? I'm going to need someone to weld up up a 2.5" o2 housing for that T3. I *could* get a guy on the forum to do it, but he wants me to mark up the original o2 housing where it aligns with the turbo, then send it to him. The whole process is just going to be a hassle, and take way too long. I understand why he wants to do it, since he can't be here with the car.

It'd be great to go v-band, though, like we talked about.

[Domino81]

Ugh, just when I thought we wouldn't get anymore snow...

[KLDE Wagon]

It's only February...



Jeremy

[Domino81]

I can't wait until I don't have to call Syracuse home anymore. I hate this weather.