cumbercr

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?

DanielRicany

Yes that does seem too rich. Not sure how to modify it on the 165, but my tuner told me he wanted 13:1.

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.

JackDidley

Look at your power enrichment tables. I dont have that laptop handy but it should have PE v RPM tables.

cumbercr

So decreasing the numbers should lean the mixture? The current value in the RPM range is 3.1.

JackDidley

You should have PE v temp and PE v RPM. You can add or subtract any % at whatever RPM you need. I am at around +30% at all RPM on both tables.

MrWillys

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.

cumbercr

Thanks. That's the number I was looking for. I'm fortunate that DA is pretty constant here. I'm at 100 feet above sea level with a very mild climate.

tunedport85inject

my 85' 870' goes in the low 11 high 10s at wot...waaaay rich...

MrWillys

Have you tried leaning out your PE table to lean it down to the 12.5:1 range?

MikeT 90 C4sixer

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.

tunedport85inject

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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cumbercr

I do have a wideband. It's not easy to read the wideband and tach at the same time I'm trying to keep the car pointed straight. But it looks like the gauge is reading high 11's to low 12's. At WOT my O2 sensor records at .900ish.

MrWillys

Using your narrow band and datalog in the comfort of your home steeping through it you can tune to .860.

MikeT 90 C4sixer

AE is not the same as PE. Look for 2 tables of PE vs rpm and PE vs coolant. Those are only ones you need for WOT AFR. I started tuning on a MAF 165 Fbody, still have it, now have a 90 C4 with SD system. They both have the same kind of PE tables for WOT AFR.
Nice gages!

MikeT 90 C4sixer

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!

cumbercr

I've looked into WB logging hardware. It looks like the equipment is kind of pricey. But it sure would be handy.

MikeT 90 C4sixer

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!

cumbercr

I have an Innovate LC-2 controller. I had no idea you could wire into the 165 ECM. I'm really curious how you did it. Correlating AFR to all the other outputs would be extremely useful.

MikeT 90 C4sixer

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.

wydopnthrtl

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.