VPC and S-AFC?

[EROK006]

Well I just got my AFC and of course have a question......I've had my VPC for a while now and have it tuned pretty good. Now I just got a AFC. My question is does it matter where I start tuning. On the VPC should I set the knobs somewhere and leave it alone. Or is there a better place to have them set?

 

[GRNDSM]

Yes it does matter. VPC responce should always be around 5 o'clock, I put gain betwen 7 and 9 o'clock and idle between 7 and 12 (what ever keeps me idling best). I then use SAFC to go from there.

Leon
RR

 

[sunflashx]

Originally posted by EROK006
Well I just got my AFC and of course have a question......I've had my VPC for a while now and have it tuned pretty good. Now I just got a AFC. My question is does it matter where I start tuning. On the VPC should I set the knobs somewhere and leave it alone. Or is there a better place to have them set?

"Tuned pretty well" So I guess you figured out the knock issue you were describing in another thread a while back?

 

[EROK006]

Yeah most of my knock is gone....new lifters and knock sensor. I still get alot of knock if I floor it at a low rpm in any gear except for first and second. Then it bleeds down once my turbo spools. Kinda like if it was running really rich and once I started flowing more air and was able to burn more fuel...I don't know.

 

[EROK006]

Also where does the air flow sensor wire go when hooking the SAFC up with a VPC? I guess I had that hooked up wrong (like on a non-VPC car).

 

[GRNDSM]

Originally posted by EROK006
Also where does the air flow sensor wire go when hooking the SAFC up with a VPC

I am not sure what you are asking... Are you talking about the MAS plug? If you are, it is just left unused.

Leon
RR

 

[EROK006]

Someone told me you have to hook up the SAFC a little different with a VPC than without. I'm just curious what wires go in different places than others.

 

[jw]

The connection should be like:
MAP->VPC->SAFC->ECU

 

[greathuskie]

VPC means????

 

[jw]

Vein Pressure Converter. It's a speed density system. Instead of using MAS to measure airflow. It uses MAP (manifold absolute pressure) and convert the signal to hz that our ECU understand. You have the advantage of eliminating the MAS (reduce intake restriction) and vent the BOV to atm . Also, run cold air intake if you upgrade to a FMIC.

 

[sunflashx]

Originally posted by EROK006
Someone told me you have to hook up the SAFC a little different with a VPC than without. I'm just curious what wires go in different places than others.

*sigh*.

 

[EROK006]

Sigh....yeah yeah I got it figured out...although no thanks to me

 

[jdmawd]

I put gain betwen 7 and 9 o'clock and idle

Why do you recommend setting the gain at 7-9. I was told to leave the gain at 12. make the base adjustments with the s-afc and use the gain as a global fuel adjustment. im not saying you are wrong. im just asking the reason.

 

[GRNDSM]

First of all bare in mind that I mainly tune for running on race fuel. So I can afford to run a bit leaner than most people. Having said that, I have never been able to keep it lean enough with VPC. Even with 450's and a 16G, when my car was running low 12's, I had gain set at 7 o'clock (full lean). With the 550's I had to keep the same lean setting. So now, when I tune with then SAFC, I keep in that range (which I am very comfortable with) and adjust it from there.

Leon
RR

 

[KenTSIII]

Leon,

What kind of hrtz readings do you see on the SAFC while running the VPC? On my car & another local car the hrtz readings seem to be really low compared to what they were before the vpc. Also do you recomend the 550 or 660 chip for AGP L2R to Red sized turbos. Running FIC 650s w/ the L2R & RC 720s w/ the Red.

 

[jw]

Funny you said that, I was wondering about that myself for a while already. At 20psi using 660 chip on a Green, I get reading max at 1800hz from the S-AFC.

 

[GRNDSM]

Ken,

To be honest with you I rarely check Hz readings. So I can't be of help there.

As far 660 chip. I have heard different opinions about it. It basically leans you out 10-15% across the board, which should be a good thing. But I have heard of different results from people who were using it. Since I am still running 550's with 550 chip, I will save my judgement until I start running that chip.

Leon
RR

 

[NJGSX96]

On my 20G and 20psi running the 550 chip and 650 FIC injectors, I see anywhere from 2000-2100Hz.

 

[jw]

Since we are in this topic, I have always wondered what others are getting comparing to mine:

1) Airflow hz when the car is off - 85hz-100hz
2) Intake temperature from logger - 62-67F (vary a little from day to day)
3) Barometric pressure - ????

 

[GRNDSM]

>On my 20G and 20psi running the 550 chip and 650 FIC injectors,
>I see anywhere from 2000-2100Hz.

What timing do you get at this point? My theory is if you run lower MAS signal, like 1500-1600Hz, you get much better timing maps… At least that is what I was getting with my 14b (27-28deg of advance). On my T3/T4, I never saw more than 19-21 deg.

>1) Airflow hz when the car is off - 85hz-100hz

Same here. Did you notice how you can move up to 200Hz with gain and idle knobs?

>2) Intake temperature from logger - 62-67F (vary a little from day to day)

VPC does not change temp sensor to the ECU. It uses “60 something” degree map and adjusts if from there.

>3) Barometric pressure - ????

I am using TMO logger with boost logging feature. I am tapping off VPC MAP sensor. That sensor does not see above 24-25psi… Even though being a 3 bar MAP, it should read up to 29. something…

Leon
RR

 

[NJGSX96]

Originally posted by GRNDSM
>On my 20G and 20psi running the 550 chip and 650 FIC injectors,
>I see anywhere from 2000-2100Hz.

What timing do you get at this point? My theory is if you run lower MAS signal, like 1500-1600Hz, you get much better timing maps… At least that is what I was getting with my 14b (27-28deg of advance). On my T3/T4, I never saw more than 19-21 deg.
Leon
RR

I get from 19-22° timing. I did notice that when I leaned it out a little it dropped my Hz to low 1900s, even dipping into the high 1800s, I did notice another 2° of so by the top of the gear. Any leaner though and I got some good knock. 19-22 make me happy.

My friend on his Big16G gets a gratuitous 25-27° of timing on 18psi and 1900Hz.

 

[GRNDSM]

Well, I guess the trick will be to run 1600Hz, but with a lot of fuel. I suppose you could do that with oversized injectors or with high base fuel pressure. I will have to give it a try.

Leon
RR

 

[TSi92]

http://gc.dsm.org/faqs/VPCAFC1g2g.htm

I have VPC 450 chip with AFC 450 injectors (gonna put a set of 720's this weekend). My vpc settings are response 5 o clock, idle 1 o clock (still can't idle for #@%#@%#@%#@%) gain 11 o clock.

My question is that 720's are pretty big injectors, kinda overkill for my 20G but is my old style AFC be able to lean out enough even though it only goes to 30% instead of 50% like the new style? Do I need at least a 550 chip? (fried my 550 chip put it on backwards ). Can't wait to install the 720's and tune the thing and then take it to the track.

 

[GRNDSM]

I haven't tried anything this radical, but would be interested in hearing your results. My guess is that you will have a hard time getting it to run well...

Leon
RR

 

[jw]

It will be easier to get it to run with 550 chip. From calculation standpoint, you have to lean it out ~37% using the stock chip with 720s. My guess is with VPC leaned out fully and the AFC too, it will barely make it. Tuning window is going to be very small with no room to lean it out anymore. However, it will still be interesting to see how it works out .