Auto VE questions

[98ls1blackbird]

I have two questions right now.

1. I have followed the Auto VE tuning tutorial and have logged and updated the primary and backup VE tables three times now. The car runs good now, but it ran alright before. The question is, logging while driving seems to only log cell data that is hit during normal driving. Even if I do a couple of WOT passes, the cell count is so low that they are filtered out due to low cell count. How is the PE mode tuned, or is that not covered by the AutoVE procedure.

2. What are the advantages or disadvantages of just leaving the PCM in open loop? Is there any advantage in reenabling the MAF?

Sorry if these questions are basic, but I'm trying to learn, and not hurt my car too much.

[Doc]

1. For your setup as it is right now, bolt-ons, you are going to find that the VE table is pretty much inline with the factory settings- as it should be. If I was to setup two identical bolt-on cars side by side with the only difference being one running the MAF and one SD I should find a negilible difference in performance. Now, throw in one in OL and the other in CL then things start to get a little more complicated. The car in CL will be able to account for day to day, hour to hour weather/temp/air density,etc. conditions. The OL car without Realtime feedback from say a WBO2 using RTACS will only be as good as the last "wash/rinse/repeat." What you are observing is the limitations of AutoVE without a feedback loop to constantly update the A/F calculations. Furthermore, having to be stuck in the low resolution backup VE table (in the case of the early OS's)is clouding the whole picture even more.

Am I saying you are hosed? No. You should be able as countless others have using AutoVE to fine tune your VE table thru interpolation of the filtered readings you are getting to ~ +/- 1-2% which is alot better than stock. Turn the MAF back on, while still in OL with no fuel trims and you should be able to tighten that table up as well. With both VE and MAF recalibrated go back to CLMAF mode and you are on your way.

2. Hitting the areas above 4kRPMs is/are going to be challenging in a 3-D table like the VE. As you have already found out, hitting the different load values is not easy on public roads. Once you do have your VE and MAF recalibrated for the mods you have, then you have to start working on the overall commanded fueling values which at WOT come from the richer of either the PE table or the fueling while in OL table.

Remember AutoVE redefines characteristics of the fueling due to the mods, and your ultimate goal is to have your end results as recorded by your WBO2 match what you are commanding.

The PE table is a low resolution 2-D table that cannot account for different load values at the same RPMs forcing you to make compromises within the 400rpms increments. The stock fueling while in OL has a tad bit more resolution however, it is based on ECT vs. MAP. This is where the advantages of the Custom OS's come into play, more resolution (RPM vs. MAP) to account for varying load/road conditions. Knowing what to command at what rpm/load value is really another subject that has been beaten to death on this forum.

Unfortuneatly, the Custom OS's are not availible for the 97-98s. The good news is you at the end user level can upgrade your vehicle/OS/cal to a 99+up pcm all by yourself with the software/information/end users found here at EFI Live.

Sorry to be so long winded.

[98ls1blackbird]

Doc,
Thanks for your input, I dont think you were long winded at all. One thing is a little fuzzy though. When you said to reenable the MAF in OL, do I just plug it in and relog the data on a test drive, or do I have to make some program adjustments also? I think I want to return to CL because it does not want to idle perfect anymore. It seems to hunt up and down, kind of reminds me of an LS-6 BBC with a roots type supercharger I had years back.
It is kind of hard to do any wot runs on public roads as this thing fries the tires at will and hits any speed limit in seconds.
As for updating to a 99+ PCM, I dont know, I'm about as handy as a cub bear with mittens