Synapsis

This is on a $8D 730 system. 24# injectors, L98 engine, headers, ported plenum, MSD 6A.

Tunercat has the table that adds fuel to the A/F ratio in PE. What is the base number that it's added to? Does it use the VE table values then add the value to that?

I've recently tuned my VE tables (dead center in the A/F ratio gauge, I love to see it there finally), but at WOT it goes full rich, which I assume is normal to some point, but I also get a little smoke and raw fuel smell from the pipes. Now I know that the stock O2 is no indication of anything other than 14.7:1, but I actually register .980 - 1 v on the O2 sensor after about 1000' in the 1/4. It looks like I go richer as the RPMs climb. I just want to know if I'll be safe leaning out the upper RPM PE table since there's no "final answer" or "P730" post about tuning PE yet, that I've found by searching.

Grumpy

No one can forecast if you can lean out the top end of your car.

Looking at the plugs
Guaging performance by stopwatch
A WB can help the novice here.

Go slow, say 2% and see what happens.

Might take 2-3d timing out of WOT and just be a little conservative. Go slow, test accurately, note trends in you notes.

The engine will tell you what's working, you just gotta pay close attention.

rooster433

I don't know if you guys have tried this or not.

For the $DA2-DA3 there is a formula regarding PE tables in the Definition Help File.

It goes somthing like...

PE AFR = 14.7 / (1 + %Change vs Cool/100 + %Change vs RPM/100

I set the %vs. Cool and %vs. RPM to equal what ever I want the A/F to theroreticaly be, say around an average of 13.1

I leave the unusual looking curve in the PE vs RPM alone. I do this for the simple fact that GM must of had a good reason to have more fuel anticipated in different RPM. For example in the DA3 there is a spike around 3900-4200rpm right where the car comes back from a gear change.

I then tune the high VE table until I get the O2's to read around .855-.880mv usually the car performs best somewhere in that area.

This is just what I do. I'm not calling it right but it seems to do great for me.

Grim Reaper

Once your engine is at proper operating temps and in closed loop, you don't need the %Change vs Coolant. That table is only for open loop/warmup mode. It is PRECISELY that table (%Change vs Coolant) why our cars are such dogs when you re-start your engine hot, boot it and go slower than molasis...you are getting too much fuel.

PS: The stock 02 sensor is not useful for WOT tuning. I wish I had that graph that shows the Voltage vs AF range of the Stock O2 sensor, you'd see WHY immediately...it's designed to oscillate around .450 volts....not measure accurate WOT or LEAN ratios.

As Bruce said: WB O2, plug cuts and performance measurements are the three methods that work. And it is best to use them TOGETHER. I am STILL working on my WB O2 sensor, so I only use the latter two methods (for now) and I can tell you that my O2 readings vary and are inaccurate - both in WOT and when I use Highway Mode. Once I get my WB O2 working, I plan to do a post that will FINALLY put a knife to using the stock O2 sensor. It's a Useless tool.

91L98Z28

Do you know off hand how long that table is used after startup? I just looked at it, and it is enriching the mixture 15% at 80C (176 F) and 5% even at full operating temperature (197 F and above).

Grim Reaper

Until the ECM goes into closed loop.

rooster433

Ve tuning is critical for any tuning. You must look first at the purpose of VE tuning. To provide the computer with critical information about the engines therorectical fuel useage. Therfore every table is baised on our VE tables.

IF you provide the PCM with the proper values than PE, cold start and other tables should be accurate.

rooster433

Sorry for replying so soon.

My guess is to:

Provide the PE equation with the value desired then aquireing that value by %error.



note its 2am and returning home from long nite of parting.