This is for an '87 350 tpi automatic. I've been prom tuning for a bit now and have upgraded from the 32B bin to the 6e ARAP. I have messed around a little with the PE vs. RPm tables and the AFR was 12.44 at WOT with 920-950 mv. I increased the PE vs. RPM from 2800-6400 from -7.87 to +7.81. The results were AFR 11.6 WOT and nearly 990 O2mv. Someone told me once that the O2 should be about 820-850mv at WOT. Does high O2mv mean too rich or lean??

Anyone have any input on this. The plugs look o.k., a couple of them are darker than others, but most have a grey/dark grey tint to the inner portion of the plug. A couple have some black on the inner portion. The car runs o.k., but it seems short on h.p., especially when you hit the throttle. timing changes to the SA table don't seem to help a whole lot.

Any input would be of a great help. Would adding fuel cause the O2mv to drop or rise and also what would be the effect on the AFR????

Thanks,
Chris

 

Most would say it depends on the motor and whwat it wants, but a NA motor make power/torque between the following AFR 12.7-13.0. The higher the O2 mv, the richer the AFR. Also, timing will affect this as well.

 

Thanks for the info. Timing has not been changed too much yet, so I'm going to alter the PE and the SA a little here and there in the upper rpms and see what affect it has. The car seemed run better with the O2 at about 850mv or so before I changed over to the 6E ARAP bin.

 

That is too rich. Zero out everything in the pe vs. rpm table and use that table to fine tune the afr. Use the 22.7 in the pe vs. coolant table to get you started. 14.7/1.227=11.98:1 afr Tune from there.

 

Thanks. Actually I got everything dialed in using the PE vs. RPM table. WOT AFR is now 12.46 and O2 is 850mv...

 

You will want to lean it out further than the 12.4.
Typically, the motor will run best with A/F in the 12.8-13.0 range.

What are you using to guage actual A/F ratios?

www.geocities.com/dzperf

 

Thanks, I am going to lean it down further yet.

To gauge the AFR, I am using tunerproRT and reading the plugs every time I get back from a drive. They are still showing some dark areas on them.

Thanks,
Chris

 

Mine ended up showing .890-.910 when the A/f was in the 13.1 range...