Air/Fuel Question
01-22-2007, 11:43 AM
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Air/Fuel Question Took a pass at the track with my new motor. MPH seemed a bit low. Borrowed a buddies scan master and made a pass. My o2s were 933. This seems too rich to me? Good news was no knock retard. Do you guys think this richness was hurting me in 80 deg. weather? Thanks in advance!!
Paul
Paul
01-22-2007, 12:13 PM
#2
http://www.wmsracing.com/o2/tech.htm
You cannot use narrowband sensors to tune...they are only accurate at stoich...I've seen 850mv=11.8:1 actual wideband verified in my GTP so you can't go by what the stock sensors say.
You cannot use narrowband sensors to tune...they are only accurate at stoich...I've seen 850mv=11.8:1 actual wideband verified in my GTP so you can't go by what the stock sensors say.
01-23-2007, 08:58 AM
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I appreciate your input, but, I'm not looking to tune with a scan master. I was simply asking if 933 was very rich. I will be buying a tuner soon, but was just wondering if the indicated #s were rich.
Paul
Paul
01-23-2007, 01:55 PM
#7
If you are going to do this, start researching a wideband. As foff667 intimated, you will need to weld a bung in your exhaust and install a dedicated O2 sensor. Then you can at least see the true current reading.
After that, you will need your tuning software to mod the PCM settings.
After that, you will need your tuning software to mod the PCM settings.
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01-23-2007, 04:35 PM
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Originally Posted by foff667
http://www.wmsracing.com/o2/tech.htm
You cannot use narrowband sensors to tune...they are only accurate at stoich...I've seen 850mv=11.8:1 actual wideband verified in my GTP so you can't go by what the stock sensors say.
You cannot use narrowband sensors to tune...they are only accurate at stoich...I've seen 850mv=11.8:1 actual wideband verified in my GTP so you can't go by what the stock sensors say.
01-23-2007, 04:53 PM
#9
looks like lamda...I've also added that and a bunch of other links & a short description to our stickies on the hptuners forum so hopefully people will understand you really cannot judge rich or lean with them other then leaner or richer than stoich
http://www.hptuners.com/forum/showthread.php?t=9919
http://www.hptuners.com/forum/showthread.php?t=9919
01-23-2007, 05:02 PM
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Originally Posted by foff667
http://www.wmsracing.com/o2/tech.htm
You cannot use narrowband sensors to tune...they are only accurate at stoich...I've seen 850mv=11.8:1 actual wideband verified in my GTP so you can't go by what the stock sensors say.
You cannot use narrowband sensors to tune...they are only accurate at stoich...I've seen 850mv=11.8:1 actual wideband verified in my GTP so you can't go by what the stock sensors say.
01-23-2007, 05:04 PM
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Originally Posted by WS6HUMMER
Listen to foff667. Trust me when you get your tuning software and need help he's the man, you want him as your friend.
bill is a very knowledgeable guy when it comes to HPT , and he is the go to guy when it comes to getting your car tuned!
01-24-2007, 07:30 AM
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Originally Posted by 98TADRIVER
bill is a very knowledgeable guy when it comes to HPT , and he is the go to guy when it comes to getting your car tuned!
01-24-2007, 09:55 AM
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Originally Posted by foff667
I thought I answered that question but here goes again
933 can be rich or lean, but will be RICHER than 14.7:1
933 can be rich or lean, but will be RICHER than 14.7:1
I know that narrow bands are only accurate at stoich.. However is this true that if they reach 930+ they will be richer than 14.7? And will Not be leaner than 14.7?
The reason that I ask is that my wideband has been reading 18-20 afr with 5psi of boost. Seemed to me like I would have blown the motor with this but I havent even gotten any knock. I keep upping my PE but it still reads very very lean. I assumed something was wrong with my wideband... My narrowbands are reading from 940 to 980 and I have gone from running 75% IDC to 130 IDC with my 50# injectors.. Just seems to me that it must be going rich and the wideband is messed up. I just installed a new wideband but have not have time to test it. .
01-24-2007, 12:00 PM
#17
Launching!
The bottom (x-axis) units on both graphs shown in that link are lambda. The first one is the transfer function for a narrowband, the second for a wideband.
For gasoline lambda=1 @ 14.7:1 a/f ratio. Lambda = current a/f divided by stoichiometric a/f. So, 13:1 would be 13/14.7 = 0.88 lambda. Make sense? Egninerrs use it because we are often targeting 14.7:1 a/f ratio and lambda gives us a measure of how far away from that we are.
The slope of the binary sensor's output varies with temperature. The hotter it gets, the more aggressive the slope, but it always crosses .450v at lambda=1 (14.7 a/f for gasoline). This slope shift is why it's not possible to accurately determine anything other than "richer than stoic" or leaner than stoic" from them. Even this requires that the be at least warm enough for the slope to register significantly with the PCM. (Hence warmup times before going closed loop!)
For gasoline lambda=1 @ 14.7:1 a/f ratio. Lambda = current a/f divided by stoichiometric a/f. So, 13:1 would be 13/14.7 = 0.88 lambda. Make sense? Egninerrs use it because we are often targeting 14.7:1 a/f ratio and lambda gives us a measure of how far away from that we are.
The slope of the binary sensor's output varies with temperature. The hotter it gets, the more aggressive the slope, but it always crosses .450v at lambda=1 (14.7 a/f for gasoline). This slope shift is why it's not possible to accurately determine anything other than "richer than stoic" or leaner than stoic" from them. Even this requires that the be at least warm enough for the slope to register significantly with the PCM. (Hence warmup times before going closed loop!)