SPDST3R

As some of you know, I recently dynoed my car and got a decent result with all the mods that I did. Unfortunately, I wasn't able to setup my S-AFC because the computer wasn't picking up my RPM. So I came here in the forum to ask for guidance on tuning my S-AFC. SEARCH helped a lot too. So with all these, I learned quite a few things... A/F, MPH to RPM conversion, EGT, and other things related to "air & fuel." Now, through this thread, I wanted to share what I learned by tuning my S-AFC and post all my results in this thread. I don't know how this thread can help but I think some of us will benefit from it.

Disclaimer: All data on this thread are for informational purposes only. Use at your own risk!!!

SPDST3R

Sep 21, 2002
Here is my dyno run result from ATP at Fremont, CA (S-AFC not tuned):

Dyno Result

osdesigns

ATP last Saturday was a great event.

Since the RPM are not registered, your adjustment on the AFC will not do much on the dyno.
If the current connection is a problem to you, there is always other sources to tap in for Tach signals.

looking at your dyno graph. your Air Fuel ratio seems to be running at desire range.... minor tweeks should get you another 15 horsepower easily.

SPDST3R

Sep 22, 2002
I posted a thread to help me interpret my dyno result and I was surprise to know that my car actually did a pretty good job on the dyno. I also asked about the A/F Ratio and here are some info that I found out:
[list=1][*]On the dyno sheet, the A/F ratio is in the range of 10 - 18. According to some of the post, N/A car runs best at 12.5:1 and some other says its 14:1. I can't confirm which is true so I'll leave it as it is for now. But I've seen a lot of post where it states 12.5:1.[*]I also learned that when the A/F ratio has a higher number (above 12.5), it means that the car is leaner. And below 12.5 is richer.[/list=1]

So by looking at my A/F Ratio result, I can easily tell where I am lean and rich. But the problem is, my RPM wasn't registering on the computer when it was dynoed so all its showing on the dyno sheet is MPH. Through the help of another forum member, I was able to figure out my RPM and Torque by the following conversion formulae:

RPM = (Speed mph * Rear Axle Ratio * Transmission Gear Ratio * 1056) / Rear Tire Circumference in inches

Torque lbs-ft = (Horsepower * 5252) / RPM

SPDST3R

On my dyno sheet the A/F ratio is shown in MPH. Since the S-AFC can only be tuned in RPM ranges (1000 increments), I will need to find out its equivalent RPMs. First of all, I have to figure out what gear was used on the dyno run. That is actually easy just by looking at the dyno sheet. My highest MPH is at 85 MPH. Normally, at the dyno run, they they would step on the gas until its close to rediline. That means, it was on 3rd gear because my car runs at around 85 - 90 MPH on third gear at redline, which is 7000 RPM.

Now that I know what gear I was at, I can find out my equialent RPM by either using the formula or find it out while driving.

SPDST3R

Sep 24, 2002
Out of curiosity, I drove my car and brought a pen and paper with me. On 3rd gear, at each RPM, I tried to write down the equivalent MPH. Yes, that was while I was driving. I know that's a stupid thing to do while driving at a fast speed

Remember, my car is an 88 N/A. Each cars are different so don't compare this with yours unless you have the same year and mods as I am. Here is what I gathered:

3000 RPM - 40 MPH
3500 RPM - 50 MPH
4000 RPM - 55 MPH
4500 RPM - 60 MPH
5000 RPM - 70 MPH
6000 RPM - 80 MPH
6500 RPM - 90 MPH

These numbers are not 100% accurate.

At this time, my S-AFC is still not tuned and just for recording purpose, the highest reading I can get for the AFL is 36.x%

SPDST3R

Sep 24, 2002
Ok, so I pulled over at a parking lot and tuned my S-AFC. Here they are:

1000 - 0%
2000 - 0%
3000 - 8%
4000 - 12%
5000 - 2%
6000 - 0%
7000 - 0%
8000 - 0%

Findings:
I don't know if this is just psychological, but according to my "butt dyno," it's pulling stronger on mid and high RPM. I'm pretty sure I gained some power. The maximum I got for the AFL is 43.2 and 6928 RPM.

Then I tried a samll tweak by increasing 6000 RPM to 4% and to my surprise, the max AFL is now reading 50.4. I don't exactly know what happened but I can tell for sure that the S-AFC is working!!!


Now I need to go back to my dyno sheet and study it more before I tune my S-AFC agian and do another run.

von

Without S-AFC tuning my A/F% is 50.7% on my GXLN/A in a first gear run to 7300rpms. Then I saw a cop wich almost pulled me over. Awsome thread Spdstr. I have one to with my findings.

SPDST3R

Yup, it was a great event.

I called ATP about that RPM thing and they told me that it was their computer. They said that their computer does this on most of the 2nd gens. Weird!!!

SPDST3R

I tried to go beyond 7K RPM but the redline beeps on me at about 6920 and I'm just afraid to keep on going.

Rotormax_4169

hey man, your mods seem to be on the sam e track as mine minus the s-afc. just curious, have you made an 1/4 mile times yet?

SPDST3R

Once I'm comfortable with my setup, I'll try the 1/4 mile

SPDST3R

I learned something new again today. Correct me if this is wrong. When I was tuning my Air Flow Correction Setting, I can only set them at a 1000 RPM increment. You can actually narrow each RPM down to 500 by going to Ne-Point setting. I think this will give you a more precise setting point.

I had to post this because the manual didn't clearly stated what the Ne-Point setting is for.

jmseven

Good write up.....

SPDST3R, I would recommend you come up to Sac Race Way on a Friday night, details:

Regular Drag Strip Testing
Friday Nights April-October
Gates Open 4:00p.m. - Run 6:00 - 10:00p.m.
Car/Driver: $40 - Spectators: $7

You can run all night and tune your car. I just live up the street on Excelcior, new housing community. Stop on by and I can go with ya. I used to go when I had my T2...well worth it.

osdesigns

ATP last Saturday was a great event.

Since the RPM are not registered, your adjustment on the AFC will not do much on the dyno.
If the current connection is a problem to you, there is always other sources to tap in for Tach signals.

looking at your dyno graph. your Air Fuel ratio seems to be running at desire range.... minor tweeks should get you another 15 horsepower easily through out the mid range.

osdesigns

since the dyno did not pick up your ignition signal, if you say you have let out at about 7k rpm, then you should be able to shift at a higher rpm.
Looking at the dyno graph, you are still making power when the throttle was let off. May be by keeping in the throttle a little longer, you might see 5-10 more horsepower~
It is okay to go beyond 6920rpm on the turbo2 engines. But don't stay at 9000 for a long period of time.

DaleClark

iTrader: (55)

The timing pickup should be put on the #1 trailing wire. If their computer can't pick that up, something is really broken - it's a really simple signal pulse to pick up, it's nothing fancy.

Dale

DaleClark

iTrader: (55)

The Ne-Points are the adjustment points where you modify your fuel curve. I believe there are 8 Ne-points.

You can set each Ne-point to whatever you want, just as long as they're in numeric order. The RPM value of Ne1 has to be lower than Ne2, which is lower than Ne3, etc.

So, if there is a particular area where you need more resolution in tuning, you can move the Ne points around to accomplish that.

The Super-AFC is one kickass device - very powerful and flexible.

Dale

SPDST3R

But I don't have TII

jmseven, we can probably get together after the sevenstock.

jmseven

Oh...yeah. Sevenstock. How can I forget. Please take tons of pics (dig.pls)

I am not going anymore. My new T2 will not be ready until the end of November. I was going to pick it up and drive it directly there......next year.

thedguy

BAH! Unless you have no other ride, you should still come. I don't have a 7, YET! but i'm still going.

SPDST3R

Something is broken ony my car or their computer?

rx7_turbo2

Maybe someone can sort something out for me. The SAFC uses the stock ecu to add fuel, regardless of the number of points on the SAFC to add fuel, are you not still limited to the ecu's 4 points. This would mean for every point the ecu uses it would be adding 2 or 3 from the SAFC. So in essence your not gaining any resolution, just dumping fuel in at the same 4 points.

jmseven

I know....I know. I have a '90 vert also. I had the intention of going. I will just depend on other to send me the pics.

Personally, I would rather buy new wheels.....