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View Full Version : How accurate is the AFR?


SSThunder
July 24th, 2007, 02:06 AM
I don't have a wideband hooked up so I'm wondering how accurate the EFI scanner is in measureing AFR? I'm hitting 6 KR with my new pulley and the scanner is showing AFR of over 14. My truck is a 2003 AWD Silverado SS with a radix with a 3.0 pulley. I've got all the normal bolt ons(headers, exhaust, cai, plugs, plug wires and 160 degree stat.
limited cv8r
July 24th, 2007, 02:12 AM
what PID are you using to log the AFR you are seeing? commanded AFR or wideband AFR?
SSpdDmon
July 24th, 2007, 02:17 AM
I don't have a wideband hooked up so I'm wondering how accurate the EFI scanner is in measureing AFR? I'm hitting 6 KR with my new pulley and the scanner is showing AFR of over 14. My truck is a 2003 AWD Silverado SS with a radix with a 3.0 pulley. I've got all the normal bolt ons(headers, exhaust, cai, plugs, plug wires and 160 degree stat.

If you're logging AFR in the scanner, you're logging commanded AFR. As for accuracy...well, I can command the neighbors dog to rob the bank down the street and give me the money. It doesn't mean he'll do it though. :lol:
SSThunder
July 24th, 2007, 02:29 AM
If you're logging AFR in the scanner, you're logging commanded AFR. As for accuracy...well, I can command the neighbors dog to rob the bank down the street and give me the money. It doesn't mean he'll do it though. :lol:

I see. So I guess I need to get a wideband hooked up and scan that way.

Thanks, Jeremy
TAQuickness
July 24th, 2007, 04:53 AM
Jeremy - Welcome to the forum. A wideband O2 is a must for accurate tuning. Feel free to post up any other question you may have.
johnsZ06
July 25th, 2007, 04:40 AM
If you're logging AFR in the scanner, you're logging commanded AFR. As for accuracy...well, I can command the neighbors dog to rob the bank down the street and give me the money. It doesn't mean he'll do it though. :lol:

Run out of our meds did we? :D
TAQuickness
July 25th, 2007, 05:00 AM
Run out of our meds did we? :D

nah. prolly the re-fill that got him. :D
SSpdDmon
July 25th, 2007, 05:50 AM
Run out of our meds did we? :D
They make medication for what I've got??? :nixweiss: http://www.motownmuscle.com/forums/images/smilies/lol.gif
mistermike
July 25th, 2007, 10:30 PM
...I can command the neighbors dog to rob the bank down the street and give me the money. It doesn't mean he'll do it though...I did, but he spend the money on doggie snacks, rawhide toys, and a greedy French poodle. I didn't get a dime. Damn dogs.
stigmundfreud
August 6th, 2007, 02:41 PM
this seems like a good thread to post this in then :D

I'm currently tuning without widebands (yes I know!) so measuring the voltage repored on both bank o2's. If I'm right 0.45 or there abouts is 14.63 with 0.9 being something like 12.1 and 0.1 being somethig close to 15.1

its not perfect but isnt it how they tuned prior to widebands?
SSpdDmon
August 6th, 2007, 03:32 PM
900mV can be 13:1, 12.5:1 or 13.2:1. That's the point of not using them to tune WOT. They're not accurate at that AFR.

If you want to try and tune using the NB's, your best bet is to tune in closed loop using the fuel trims. It won't take care of WOT. But, it's a start.
stigmundfreud
August 6th, 2007, 03:55 PM
cheers, I'm running in semi-closed as I've used the HSV 04 clubsport as a base tune. Def getting a wideband to do it all properly but as a crude tune for now it all seems ok based on the no2 outputs.

Am I correct in thinking for the commanded afr of 14.63 they should be accurate though? so if commanded is 14.63 and the no2 mv is 0.45 then this should be spot on but purely for that afr?