Going back to FI and wanted to know if my memory is right that most of the tables in the '95 PCM don't actually change anything, right? I mean the tables like "Volumetric Efficiency", "%Change to Fuel/Air Ratio at WOT" just don't do anything, right? Or is there more information known now and there are better settings for these tables now for Procharger and Vortech superchargers?

Hal

 

I've got a good link for you to find out what the function of all the tables and how to manipulate them. To answer your question: The volumetric efficiency tables are not used at all on MAF cars unless the car is put into speed density mode either by a malfunction or on purpose. The %change to Fuel/Air ratio vs Rpm at WOT is a very important table to get your AFR dialed in during WOT.

http://www.lt1pcmtuning.com/tips/

 

Thanks! Memory was weak on what worked and the reasons why.

Hal

 

97ws6pilot, do you have any .bin file where the AF cells were changed? I've looked at a few .bin files but nobody was changing those.

Hal

 

All my stuff is .cal which is Tunercat for OBD2. Its pretty easy to tune the af ratio with the above mentioned table. I use a dynojet wideband commander which logs map, AF ratio, throttle position and RPM You just do a 3rd gear street pull and log it. Then look and find out at what rpm's you are lean or rich and either add to the number to richen it up or subtract from the number to lean it out. Then do another 3rd gear pull and tweek it again. It usually takes about 3 pulls to get it perfect.

 

I'm seeing a wide difference of price on these dynojet wideband units, are they all the same (same connectors or just spliced in)? Also, can't you just put wideband sensors in the stock locations and have the stock pcm AF tables work better?

Hal

 

Its better to just leave the stock sensors where they are. Any exhaust shop will have the bung and can weld it for you. It really doesn't matter if you weld it into the left bank exhaust or right bank. It also comes with an AF ratio guage so you can keep an eye on your engine all the time. I have mine mounted in my dual pillar guage pod. I think bought mine off ebay for about $375.

 

So putting better wideband sensor for the pcm to read off won't make any difference?

Hal

 

The PCM can't read a 0-5v wide band sensor.

 

There is another wideband called an LM-1 or LC-1 that has a simulated narrow band output but its still not as good as the GM sensor. Some people have sent the LM1 signal through AC pressure in order to log AFR through datamaster. I chose the wideband commander because it logs everything I need to tune. And datamaster doesn't work with OBD2.

 

I'm thinking it might be cheaper to use tuner cat and freescan to set up a good tune, then port it over to odb2. Does that work? I have '95 pcm/tunercat/freescan and would just need the new ODB2 Jet tunercat to change my stock pcm (so I don't have to swap back for smog).

Hal