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Runing Rich?
Thread Starter
TECH Regular
Joined: Jun 2003
Posts: 465
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From: So Cal
Runing Rich? This probably is a stupid question but how do you know if your running rich or lean. Do I need some sort of diagnostic? can I use my predator? Im not a genious when it come these type of things 
so any help will be cool.
so any help will be cool. 
Teching In
Joined: Jun 2002
Posts: 46
Likes: 0
From: South Bay Area, Ca.
Re: Runing Rich? There is no such thing as a stupid question. Yes, you can use your Predator to check if you're running rich or lean. In real time data mode, toggle down to where you see 'HO2S'. These are your feedback readings from your 4 O2 Sensors. 'B1S1'= Bank1, Sensor1, etc... . At WOT, you want these to read between 890mv-920mv. <890 = Lean, >920 = Rich.
Realize that these values are to be used as a "guideline" to whether Bank1 or Bank2 is running lean or rich and shouldn't be used for serious tuning. The only way to really check your A/F ratio is with a wideband O2 Sensor (as stated above). I gained +14rwhp/12rwtq peak, (+17rwhp/tq lower in the RPM scale) w/Predator by spending an hour on a Dyno with Wideband O2 Sensor Feedback. My A/F Ratio at peak hp "stock" was 11.9:1, and at peak hp "tuned" it was 12.78:1 .
HTH.
Nick
Realize that these values are to be used as a "guideline" to whether Bank1 or Bank2 is running lean or rich and shouldn't be used for serious tuning. The only way to really check your A/F ratio is with a wideband O2 Sensor (as stated above). I gained +14rwhp/12rwtq peak, (+17rwhp/tq lower in the RPM scale) w/Predator by spending an hour on a Dyno with Wideband O2 Sensor Feedback. My A/F Ratio at peak hp "stock" was 11.9:1, and at peak hp "tuned" it was 12.78:1 .
HTH.
Nick
Re: Runing Rich? Sorry about that short answer above, I was in a hurry that day. What exhaust system do you have? I have very close to the same mods you do if you have a Loud Mouth, and my AFR is an average of 12.6:1 @ WOT. This is leaner than stock and may be because I descreened the MAF.
Thread Starter
TECH Regular
Joined: Jun 2003
Posts: 465
Likes: 0
From: So Cal
Re: Runing Rich?
Sorry about that short answer above, I was in a hurry that day. What exhaust system do you have? I have very close to the same mods you do if you have a Loud Mouth, and my AFR is an average of 12.6:1 @ WOT. This is leaner than stock and may be because I descreened the MAF.
Re: Runing Rich? That's probably a good place to leave it unless you're trying to squeeze every last hp out of your engine. 12.8 to 13.0 is supposed to yield peak power, though.
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Re: Runing Rich? You folks with stock exhaust w/ any wideband &
dyno data, can you share any in-car O2 mV vs.
wideband O2 reading datapoints? I'm trying to
get some sort of rule-of-thumb figured out for
the stock setup, that would let me guess a little
better about what (say) 900mV really means. The
big variable is EGT and I figure the stockers
probably are relatively tightly bunched, with a
few bits of data we might be able to make a not-
bad O2 mV vs AFR curve that represents the stock
exhaust & sensor location.
dyno data, can you share any in-car O2 mV vs.
wideband O2 reading datapoints? I'm trying to
get some sort of rule-of-thumb figured out for
the stock setup, that would let me guess a little
better about what (say) 900mV really means. The
big variable is EGT and I figure the stockers
probably are relatively tightly bunched, with a
few bits of data we might be able to make a not-
bad O2 mV vs AFR curve that represents the stock
exhaust & sensor location.
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