I was noticing I was getting 2 degrees of knock at 4800 rpm. This was the only knock and happened on both 1-2 shift and 2-3 shift. I had already put the spark advance in PE back to zero in all columns. I took the slight rise in timing at 4800 in the main tables and flattened it out to 19 degrees like the other upper values in the column. At certian warmer operating temps (180 degrees) I would still see knock. I noticed that the PE fueling tables started to lean the car out at 4400 and then drop it at 4800 to 6.6% . My car shifts at 4900-5000.

Should I increase my PE in the 4400 and 4800 RPM range to correct this??? And is it best to leave the slight increase in timing on the main spark tables??? I assume its the programming anticipaitng the shift but can anyone shed some more light as to what GM wanted to happen??? Why the slight increase in timing and the decrease in fuel at 4800???

Also in the main spark table there is a drop in timing at 1200 RPM in the higher LV8 range. Is this for the converter??? If I have a 2400 stall now should I make adjustments in my spark tables for this?? If so the converter stalls right at 2400 so should I take some timing out at 2200????

 

You'll find the closer you get the MAF stuff to being right, it's little problems will get ya. No MAT, fueling, and Timing corrections is one of them. So you have to set your tune for the worst case, or rely on the K/S for protection.

I can't afford annual engines, so I run on the low side of what I could run timing wise.

Nothing bets experimenting and finding out what your car likes.
Go slow take notes, it'll all make sense, when you can start seeing trends of what your car likes.

 

LOL at irony. I took notes and carefully logged each new bin so that I could always source back to find what alterations I had made and match that up to the corrisponding datalog. Well one night I was a little too enthusiastic and rattled off 20 bins playing with my cold start fuel and IAC control,ect. I did not keep notes on these. Afterward I kept editing the bin in so many different areas to the point that it was simply easier to take an unmolested APYU bin and start over. The only bad part was that I did not record what I did to get my cold start dialed in perfectly. So with the new bin I have idle and part throttle issues for the first minute or so. The real kicker is I still have the bin on my prominator in number 4 location but I can't tell which bin it is So now I start my car on number 4 and switch it over after the car warms up to another bin..... Ah well its only temporary, I just need to go out again and do it all over.

I have kept the timing conservative at 25 degrees total timing at WOT. I will use my friends WBO2 that actually datalogs the session so you can go back and see exactly what rpm and LV8 needs more or less fuel. Before I had a WB installed into a bung in my exhaust but it only gave out a digital reading with no logging capabilities. This time getting my WOT AFR correct should be a lot quicker with this WB and a prominator.

But why on the stock chip did GM decrease fuel and increase timing right at 4800 rpm??? What benefit did they see by doing this??? Sorry if it sounds like a dumb question but I have been looking for an answer for over a week and would like to know just to help understand a bit better.

 

turn down the enables for DFcO seen it cuase knock on a few maf cars. of totaly disbale the DFcO good chance its not really shutting down the injectors in a timely enough fashion when your shifting. closed throttle, engine Decel will trip DFcO. try that see what it nets you.

decel fuel cutoff JIC you were wondering

 

Well I edited the PE% Change To Fuel/AR Vs RPM table. I increased the %change. Hopefully (because I am not sure) I added more fuel from 3200 right up to 4800.

On the same bin I also went to the constants table in tunercat and adjusted the Max Accel. Enrich Async P/W from 5.554 to 8 msec. The reason I did this as well was because when I installed my LS1 injectors I had to increase the amount of time they were open for the car to even run smooth. If I left it at the stock APYU setting the injector was not staying open long enough. I have talked to a lot of people with these injectors and nobody seemed to ever have to do this. I am at a loss as to why my injectors operate differently.FYI my pressure is set at 48psi and I run a 26 injector constant. The car actually picked up a consistant tenth to 2 tenths on the g-tech. But the most important thing was zero knock ANYWHERE. The first time ever no damned blue line came protruding up on datamaster I might actually be able to safely run my nitrous one of these months. I guess wideband is next to check AFR's at WOT.