I know I've read threads upon threads about how 2.9 is as low as you should go without bigger injectors, blah blah blah.

I think my car is an exception. I've had my 2.9 on a while, I changed my plugs for one step colder NGKs when I switched the pulley, since my stage 2 pulley was fouling my plugs with a quickness.

With the 2.9, my plugs are still fouling. I can already tell they are fouling cause of how the car is running. Also my brand new exhaust tip is caked with soot...and I know my car isn't burning oil, lol. Its still rich, so I figure my warranty will be safer with a 2.8 than it will a completely aftermarket tune, as a pulley is easier to switch than a tune if warranty work is needed...

If I get a 2.8, I will be getting the dual pass plate first, because I definitely don't want to go smaller without going cooler.

My question is this. With the 2.9, is it possible that I'm richer at idle and when not boosting, and running leaner the more psi I'm pushing? Well I know that boost leans the mixture a little, but will the 2.8 make it dangerously lean under heavy boost?

Any of you have any idea WHY my car is soo freaking rich???

I figure if I'm rich enough to still be fouling my plugs, I can't be doing any damage, so going a step smaller shouldn't hurt anything, and maybe I won't be so rich anymore.

Help me out people!!

 

Cooling Mods Required, I have been running a 2.8 for a long time Now & No Leaning out!

 

Check your IDC's, they are the true indicator of whether or not you can go down the next pulley size. IIRC a 2.8" pulley puts your IDC's well over 100%. If I were you I'd have a tuner go over your car and fix that terrible tune GM gave you.

 

why not throw it on the dyno see how your airfuel ratio is doing... you would be able to see if anything is wrong also

 

i ran a 2.9 and it leaned out my s2 injecters

 

richness has nothing to do with how much your injectors are taxed.

Your car will attempt to run whatever AFR it has commanded. with S2 its rich as hell.
it doesnt matter what you pully you use, the car is still going to try to run at that commanded AFR.

but your damn sure your injectors are working harder keeping it there when your pushing that extra pound of boost.

more air = more fuel.

 

Exactly.

 

The problem with running small pulleys with small injectors only really shows up when you run out of the linear operating range of the injector. This is not determined so much by the car as the number of injectors, ammount of air and the RPMs. You can run pig rich all the way to 6000 rpms, at which point you need to pulse 19.76 ms to get enough fuel into the cylinder and another .75ms for the injectors to recover and only have 20ms of time between revolutions. At that point, your injectors are static, you don't get the fuel you need and you go lean. These injectors are borderline static as it is with the pulley they have.

In short, you will see NO change where you are rich now by putting in a smaller pulley, but you will go way lean up top. Your richness is tune related. Sorry.

Wow! A lot of people replied while I was typing!

 

Thats what I'm wondering. I know my car is running pig rich (F U GM for your crappy tune!!!) but I'm trying to find out if there is a lean point with the 2.9, or if there will be a lean point with the 2.8.

It isn't about speed so much, just not being so rich. Even a 2.85 might put me in a better A/F range.

So there are no dynos and no one here to help with tuning. Whats the next best way to get some numbers?

 

I repeat:

you will see NO change where you are rich now by putting in a smaller pulley, but you will go way lean up top.

There is noone? Did you try the HPT forum??

 

no...I highly doubt anyone with HPT is anywhere close to Wyoming. I'll check though.

Edit: where is the hpt forum? lol

 

http://www.hptuners.com/forum/