Anyone in Middle Tennessee know how to tune, a S-afc, I am installing it on a 91 gsx, I need someone to guide me though & gimme tips on tuning when I do more mods.

VFAQ.com has a great install guide.

Basically tune it super rich to start and datalog it. Super rich you should have no knock so just keep leaning it out little by little until you start knocking a tiny bit. Richen it up again to where it stops knocking, and bam, you got tuned.

Best way to do it in my honest opinion.

It all depends on what size turbo and other supporting mods. We need more info :)

The mods I have are all free mods, 20G, balancer shafts removed, wiseco pistons, arp head & main studs. cams are (Intake 251 duration /10.34mm) (Exhaust 250 duration /9.93mm) the only thing is, I have the 450cc injectors, I am only set at 7psi right now, but It is a project car & I haven't really ran it at all, I am afraid of leaning it out with the 450s I don't think that is enough. What it a good injector I should go with here, I'm finally getting into dsms, so I wanna learn all I can to have a nice dsm. please help, any advice/ comments/ anyhting to help me out. Thankx

I have also heard that the S-AFC won't stop the car from wanting to die when you have an atmosphere vent BOV, because dsms are Karmann type sensors, Am I correct? or no

Never vent to the atmosphere unless you have a VPC or Blow through MAF setup. It's not something to do, period.

I recommend FIC (Fuel Injector Clinic) Injectors as they are all flow matched and are ball and isc style (better flow) as opposed to OEM pintle style (one spray that isn't as efficient as ball/disc.

you'll want 720's or larger I imagine on a 20g turbo if you plan on using its full potential. Also, get a pocketlogger so you can tune by knock. That's the best way to tune so get a cheap palm pilot and the datalogger software from pocketlogger.com at absolute minimum. Mach V has a new 1g tuning system coming out that is like a shareware DSMlink and uses a laptop. Check out their ECUPLus thing on Machv.com.


Also I assume you have all the necessary supporting mods such as Boost controller, boost gauge and other gauges (at your discretion). Big FMIC and upgraded intercooler piping and at least a 2g MAF. With that size turbo, your supporting mods need to be considerable. Lotsa fuel and air needed as well as ways to monitor it all. The latter being by far the most important.

Originally posted by HybriDSM
Never vent to the atmosphere unless you have a VPC or Blow through MAF setup. It's not something to do, period.

i bought my expensive ass four ply couplings and t bolt clamps from AMS yesterday. blow thru maf all the way.

I really appriciate it guy's I do have alot of stuff to do before I am going to run the car. I will do more research on air/fuel, & tuning info, if ya'll can let me know things like this I will have a bad ass gsx, thankx again, I will post when I have done more research.

650cc injectors are more than enough for a 20g.

What fuel pump do you have? What intercooler?

A 20g on the stock intercooler is a joke. You need to have the supporting mods for a 20g. That is a larger turbo than people think.

The intercooler i have is 20" x 7" x 3.5"

I have a walbro 255

Jeff, what injectors do you recommend for me.as in Brand/type I will go with 650s but from who?

Originally posted by blue91gsx
Jeff, what injectors do you recommend for me.as in Brand/type I will go with 650s but from who?

http://www.slowboyracing.com/Fuel%20Delivery/Fuel%20Injectors/650/650.html

I gotta question, what is the 1G MAF Translater, what is it, what is it's purpose does it help, info please....