Wot afr
Thread Starter
Melting Slicks
Joined: Mar 2008
Posts: 2,141
Likes: 76
From: Santa Maria, CA
Wot afr
I recently replaced my 870 ECM with a 165 and ARAP 6E bin. I did some data logging at WOT and found the Target AFR was recorded at 11.8. This seems rich to me. The question is how do I lean it out and what would a good target be?
Melting Slicks
Joined: Jun 2013
Posts: 3,065
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Some people say low 12s, high 12s, low 13s, mid 13s.
I have been through them all. I think I can feel a little more power with 13.5:1, but I fear it might be too lean and could possibly damage my engine over time, so I'm shooting for 13:1.
Thread Starter
Melting Slicks
Joined: Mar 2008
Posts: 2,141
Likes: 76
From: Santa Maria, CA
Drifting
Joined: May 2013
Posts: 1,736
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From: Reno Nevada
12.5 is lean best torque. You may modify the PE % change to AFR vs RPM table by adding, or reducing these numbers to even a negative number. This table goes to -3.9 at 3600 rpm on a stock file. Those numbers were changed to a positive in yours. Feel free to reduce these until you reach 12.5. Some swear by 13:1, but this has not been proven. Keep and eye on this as the seasons change available air density.
Thread Starter
Melting Slicks
Joined: Mar 2008
Posts: 2,141
Likes: 76
From: Santa Maria, CA
12.5 is lean best torque. You may modify the PE % change to AFR vs RPM table by adding, or reducing these numbers to even a negative number. This table goes to -3.9 at 3600 rpm on a stock file. Those numbers were changed to a positive in yours. Feel free to reduce these until you reach 12.5. Some swear by 13:1, but this has not been proven. Keep and eye on this as the seasons change available air density.
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Racer
Joined: Apr 2013
Posts: 435
Likes: 4
From: Guilford NY
Target AFR is not the same as actual AFR. how are you measuring actual AFR? do you have a WB O2 sensor? the target AFR rarely matches the actual. Most tables create a much richer target than what is actual. but i agree with *****, shoot for 12.5 for WOT AFR. the 2 tables that were mentioned create the "commanded PE AFR", via a calculation. if you want to get serious in tuning the WOT AFR, you need a WB.
Drifting
Joined: Aug 2010
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Last edited by tunedport85inject; Mar 4, 2014 at 06:17 AM.
Thread Starter
Melting Slicks
Joined: Mar 2008
Posts: 2,141
Likes: 76
From: Santa Maria, CA
Target AFR is not the same as actual AFR. how are you measuring actual AFR? do you have a WB O2 sensor? the target AFR rarely matches the actual. Most tables create a much richer target than what is actual. but i agree with *****, shoot for 12.5 for WOT AFR. the 2 tables that were mentioned create the "commanded PE AFR", via a calculation. if you want to get serious in tuning the WOT AFR, you need a WB.
Racer
Joined: Apr 2013
Posts: 435
Likes: 4
From: Guilford NY
i had the hardware and software at home and yes i have and Innovate wide band mounted on the dash wth a gauge,but not have tried ,870 calibration it's not as clear as 165,at least for me,basically a newbie on tuning,i have 5 tables for PE or AE on my calibration....
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Nice gages!
Racer
Joined: Apr 2013
Posts: 435
Likes: 4
From: Guilford NY
Do you have a way to log the WB AFRs? agree, too difficult to watch gages and drive. need to log it. 900mV for stock NB O2 is good, but need to focus on the WB to get it right. just saying!
Thread Starter
Melting Slicks
Joined: Mar 2008
Posts: 2,141
Likes: 76
From: Santa Maria, CA
I've looked into WB logging hardware. It looks like the equipment is kind of pricey. But it sure would be handy.
Racer
Joined: Apr 2013
Posts: 435
Likes: 4
From: Guilford NY
Thread Starter
Melting Slicks
Joined: Mar 2008
Posts: 2,141
Likes: 76
From: Santa Maria, CA
Well what model WB do you have? most have extra outputs, for other uses. I have an older LM1 WB on my '88 IROC camaro, and it has 2 analog outputs. i wired one of them to my stock 165 ECM, and with a modified datastream, have the WB afr coming into TP log data. it took a while to get it all working correctly, but it is waaay cool. no plans for a WB on my '90 C4....................yet!
Racer
Joined: Apr 2013
Posts: 435
Likes: 4
From: Guilford NY
Well Innovate makes some good products for sure. I looked at the LC2, and it does have the same analog outputs as the LM1. It wasnt too bad to get this data into the datastream. First you need a special cable to get the analog out line to the ECM. Find an unused pin, i think i used D8, and then need a modified datastream, that has this parameter in the ADX. Now i will not take credit for editing the ADX to make it work. Some smart folks on the F-body boards did that. But i helped test it out, back a while, and made it work. I am using a modified ARAPWB adx. It is out there for public use, on the TGO boards. If you are real serious about it, i can find the link with all the info.
Drifting
Joined: May 2007
Posts: 1,550
Likes: 324
From: Mid Ohio
I've never tuned a C4 but I have a lot of experience with OBD2 & fords.
Not knowing anything about your setup.. I'd want to start with the stock spark knock table -6 deg & a mid to low 12 across the entire range. Once its responding the way I command, I'd ultimately I'd like to see -2deg from knock, a 13.4 at first WOT and a steady decline to 12.6 about 500 rpms before the shift.
Rule of thumb.. 13.4+ is too lean for heavy loading. Less than 12.0 on a NA engine is safe but costing you power.
Each engine is a little different. And each engine has a heat rise to consider too. Some even have cyl to cyl mis-match too. It all depends on how much cyl pressure your making and for how long at high loading.
For most stock engines w/bolt ons you can't go too far off base if seeing high 12s on your WB.
Not knowing anything about your setup.. I'd want to start with the stock spark knock table -6 deg & a mid to low 12 across the entire range. Once its responding the way I command, I'd ultimately I'd like to see -2deg from knock, a 13.4 at first WOT and a steady decline to 12.6 about 500 rpms before the shift.
Rule of thumb.. 13.4+ is too lean for heavy loading. Less than 12.0 on a NA engine is safe but costing you power.
Each engine is a little different. And each engine has a heat rise to consider too. Some even have cyl to cyl mis-match too. It all depends on how much cyl pressure your making and for how long at high loading.
For most stock engines w/bolt ons you can't go too far off base if seeing high 12s on your WB.