So ive decided that I am going to give this whole self tuning thing a try. I know more than the average gearhead, so dont go telling me that it is for the professionals, because I know enough to know that there alot of shops who do dyno tuning and only touch the PE tables.

So... This is what my plan is as of right now. This is my current setup:

Budget rebuild 383 (scat 9000, scat 6" I beams, KB pistons)
LE2 heads w/ Beehive springs
236/242 .555/.576 112 XE grind cam
Longtubes
True Duals

So my plan is to run it speed density in open loop. The OBD1 PCM has a tune from Ion @ MadZ28. I am ordering a LM-1 wideband for all the tuning.

1st I plan to tune the VE tables using stock O2s and VEmaster to get the VE tables somewhat close. I realize that these will be way off for low rpm because of overlap and O2 confusion. I might also set the BLM boundaries to ignore these RPMs.

Then I will remove the stock o2s and run the wideband with MAP input (still trying to figure out how to do this) to get the tuning right. I think I could use the wideband with a narrowband conversion input into the PCM (open loop) and read datalogs w/ datamaster or freescan. Has anyone done this?

Then I will tune for WOT. Ive gotten mixed input from what the computer uses for WOT lookups in open loop SD. AFAIK it uses VE tables as a base and then to open loop AFR and PE, and picks which is richer. So I will most likely use the open loop AFR MAP vs RPM tables because its more consistent from what ive been told.

Then to spark. I need help on this one. Would I just keep adding spark until it starts to pull timing at a certain RPM/MAP and then pull it back out.

My other issues would be due to overlap on the cam, what should I target as cruise AFR (not actual AFR in the chamber, but readings on a wideband) at 1000-2000 rpm, or under load is this rahter accurate w/ a wideband? I might see if I can get access to emmisions testing equiptment to test for CO2 readings which would tell me when complete conbustion is occuring. I know for cruise, I want somewhere around 15-15.5 chamber AFR for the best gas mileage.

Any input on how accurate my logic process is?

BTW, sorry for the long post.

 

I personally don't like portable wideband units, or at least the ones I had a chance to try. They're usually not very accurate and can lead you in the wrong direction.

Why do you want to run BOTH speed density and open loop? What is your reasoning? Why do you want to run speed density in the first place?

If you are in SD, you will want to get your VE where you want it first, then you can tune the WOT too.

Spark where? WOT, part throttle?

For WOT, I generally preffer to keep the timing in the stock range for these cams. But if you want to play with it, yes, advance one degree at a time until it shows KR and then pull 2. Also, just because it doesn't show KR, doesn't mean your car is making best power at that timing. Combination of air fuel ratio and timing is also important. This is where the dyno helps more than a portable wideband.

For part throttle keep it around the stock settings - 14.7.

 

well 1st off, AFAIK speed density gives you better control over to fine tune the engine. Maybe if I used open loop, it would work with the MAF and the PCM would refrence MAF and Open Loop AFR MAP/RPM tables which would also work. I just dont really like MAF sensors and I especially dont like o2 sensors.

Im curious why you dont like portable wideband and which ones you have used and how are they different from the ones used on dynos. I have access to a dyno, so I could use that. w00t for having friends who own speed shops.

I was talking to a friend and he was telling me that 16:1 is the best AFR for cruise.

Have you ever used emmisions testing, namely CO2, to test for complete combustion?

When in MAF/open loop... does the computer use PE tables still?