holy high a/f *help*
Originally Posted by sloppymax
stoich is for partial throttle that is not under much load. at WOT and under a much higher load, the stoich comparison goes out the window. most sniffer tests that i have seen capture a leaner than actual a/f even when the unit is functioning correctly.
Originally Posted by Ziggyrama
You should get a new tuner. Just because you're not hearing knock doesn't mean it's not happening. Only severe detonation is actually audible without any amplification. You can use an electronic device to check or you can build a set of det cans yourself and listen for knock. I am not out to bash your tuner but he really should know this.
Since you just had all kinds of exhaust replaced, my guess is you have a up stream air leak in your exhaust which is screwing up your A/F readings. Maybe one of your gaskets did not seal up correctly and you have a very small leak that could be responsible for this. I assume you got the sensor stuck in your tailpipe with a clip when you were on the dyno, right? Once you do a pull on the dyno, some extra oxygen will get sucked into the stream and mess up your readings.
14s at WOT is not good, if that is really your true reading. You would not be making the power that you're making with that AFR. Your EGTs would also be very high and you would probably be detonating pretty badly at high loads....badly enough to hear. Your AFR is most likely fine.
Since you just had all kinds of exhaust replaced, my guess is you have a up stream air leak in your exhaust which is screwing up your A/F readings. Maybe one of your gaskets did not seal up correctly and you have a very small leak that could be responsible for this. I assume you got the sensor stuck in your tailpipe with a clip when you were on the dyno, right? Once you do a pull on the dyno, some extra oxygen will get sucked into the stream and mess up your readings.
14s at WOT is not good, if that is really your true reading. You would not be making the power that you're making with that AFR. Your EGTs would also be very high and you would probably be detonating pretty badly at high loads....badly enough to hear. Your AFR is most likely fine.
ur saying an exhaust leak could cause my car to read lean when its not truly lean? ill have to check that out....
Hmmm. my Z's got the borla td, testpipes, jwt intake, and the 5/16" spacer, yet the tips on the exhaust are usually a brownish tinge, making me think I'm running just right or a little rich. Every Z must be different, but didn't think there would be this much of a variency. Makes me want to get dyno'd with A/Fs soon 
Originally Posted by CH@Dbee
ur saying an exhaust leak could cause my car to read lean when its not truly lean? ill have to check that out....
There are positive and negative phases to the exhaust pulse. During the scavenge phase of the pulse, it can actually pull air in through the leak point.
This will show up as excess oxygen in the stream.
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From: Nerverland
my school of thought is running rich is wasted gas & lost horsepower. om my supra, i tuned with a s-afc, a/f, & knock sensor. my safe readings on the egt ported in my header showed that a 13.1-13.3 readings was th e perfect balance. i'm not sure why people would say a higher a/f is more risk for detonation. U would get carbon buildup, but running higher = running cooler, ie, no detonation. hope this helps.
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From: Nerverland
btw, i have '07 enthusiast san marino blue, with Borla TD, nismo dual intakes, spacer, and am convinced i am running rich as hell. I ave about 22 mpg on highway driving civilized. I am going to get some fuel managmnt piggyback and will post dynos @ a/f throughout range. U could squeeze on your setup alone, an extra 10-15 rwhp safely by tunning.
Originally Posted by moorech6
my school of thought is running rich is wasted gas & lost horsepower. om my supra, i tuned with a s-afc, a/f, & knock sensor. my safe readings on the egt ported in my header showed that a 13.1-13.3 readings was th e perfect balance. i'm not sure why people would say a higher a/f is more risk for detonation. U would get carbon buildup, but running higher = running cooler, ie, no detonation. hope this helps.
Originally Posted by Ziggyrama
You should get a new tuner. Just because you're not hearing knock doesn't mean it's not happening.
I'd also be concerned with elevated EGTs (Exaust Gas Temps) in a lean condition. You'll ruin exhaust valves if EGTs go too high.
my car is currently having a mechanical problem that's being blamed on my intakes. The machanic believes because of my intake that my A/F mixture is too lean which is causing my cars problem.
By any chance, after driving your car 5-7 minutes after a cold start, do you experiance a brief time frame of "stuttering" in low RPM's?
By any chance, after driving your car 5-7 minutes after a cold start, do you experiance a brief time frame of "stuttering" in low RPM's?
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