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View Full Version : Air/fuel guage accuracy? safe boost psi?

speeddreamz
09-18-2003, 01:17 AM
Okay well I was dynoing my car and I noticed the readings and numebers for the air fuel ratio, they said if i was approaching 12 to watch it, to go any lower is bad...or was it higher? i think lower. Anyhow... They said not to even mess with my boost controller ebcause i was leaning out toward the higher rpms. So ... i'm waiting and waiting and now i'm going to install a walbro 255 intank. I'm wondering what is a safe boost to go at... ?
3 inch dp, no cat, intake, blitz bov which isn't working rite now. I have a s-afc as well but haven't adjusted it because not enuff fuel was gettin put out for it to work. on the dyno atleast. but now that i have the pump?


and how accurate are lets say a greddy(trust) or a auto meter air fuel ratio guage? I think someone mentioned they're bull****? And if they're not whats a good brand to pick up, i have a greddy boost gauge and i love it !
speeddreamz
09-18-2003, 01:18 AM
OH yeah...that thing on the bottom about boosting 10 psi...disreuage that on my signature i'm lazy.
aeontony
09-18-2003, 02:58 PM
I can't tell you what a safe PSI to tune your setup to would be, but I can say that anything that taps off the factory O2 sensor is inaccurate to the point of being useless (i.e. autometer). Even the Greddy A/F with the special sensor (what I run) is not accurate enough for tuning. I have that coupled with an EGT but I'm taking my car to dyno-tune once it's done. It's not just worth the risk. Not to mention tuning is an art that has to be perfected :)

If you want to pick up a reliable A/F meter, you have to purchase a wideband one. I don't have the websites selling these things off the top of my head, but try looking for wideband a/f on google or something.

The higher the number, the leaner you are. The lower, the richer. Once you start getting into the higher RPMs you want to be at about 12 to 1 (which is richer than stoich, but "safe").

It's not just the fuel, either. Even if you flood the cylinder with fuel, after a certain amount of boost you will ping the engine. Then you have to mess with timing..