Cruise AF and VE tables

[Telco]

The only change I made to any knock tables was to increase allowed knock to 12 degrees when I found that I was hitting 8 degrees and 8 degrees was the max amount of knock it could pull. With 12 degrees of knock retard allowed, it's never pulled more than 11.7 degrees. So, I'm on the ragged edge there.

What I need to do here is find what's causing the truck to pull so much timing on reducing throttle conditions, not necessarily WOT to full close but where the TPS reading reduces. One point, I had 11 degrees of retard on a 5 percent reduction of throttle. I've also noted high retard at very slow speeds, such as giving a little bump in gas in a line of traffic approaching a left turn to a new road. If I can nail this one thing down, I can put the 3 degrees of high octane timing back in and get the power back that I'm missing.

On the O2 setpoint, here's what I'm running now:

CL Mode Bank-1 Bank-2
0 365.001374 365.001374
8 379.989353 379.989353
16 379.989353 379.989353
24 379.989353 379.989353
32 389.992642 389.992642
40 389.992642 389.992642
48 389.992642 389.992642
56 389.992642 389.992642
64 389.992642 389.992642

I'll look your table over now. Just so you know, I was seeing 19MPG mixed driving on the one tune, just got to get the KR dealt with. If I can, I think I might be able to more selectively adjust timing and tweak up to a full 20MPG with city driving, AND be able to spin the tires through first and into second like it was before. I figure I'm about 80 percent there, and if I can get 20 out of a full size 5.3L I'll feel very confident about getting 25+ out of a 4.8 in my own S10. Or, if I go the way my dad wants me, 30+ out of a 3.8L V6.

[cmitchell17]

I never had any luck advancing timing in the low airmass cruise cells.

Although I did not really do any testing, I just never felt in increase in torque.

If you think about it at the low load cells gm spent millions of dollars making a spark table to provide the best economy and emissions. (Emssions always wants MBT timing right? gm would not take out timing for emissions would they?)

But at high load they decreased timing to allow for 87 octane regular gas.
(which makes you think you could get MBT timing for all loads with 87, but then you figure you better run 87+ after you hear knock)

So what I did was use a blend of the high octane table and the optimal timing table. I blended about 80high octane/20 optimal timing in the airmass cells above 1800-2000rpms (Under 1800rpms I kept the timing stock becuase the TC likes to lock making you push the throttle more and then you have more airmass and it likes to knock)

Then I added the rest of the timing through the fuel mixture spark correction table so it would only come in at PE.

[BlackGMC]

IMO your running WAYYYYYYYYYYYYYYYYYY to much timing..... You need to go back to a stock timing table and increase in small amounts, then adjust your VE table, the log, then repeat.... Also your PE table is WAYYYYYYYYY to lean, your commanding 16+ AFR while in PE.... Also your Commanded Fuel while in OL table is also really lean in the wrong areas 85kpa+.... IMO if you continue to drive the vehicle your going to shopping for a new motor very sooon....

[dc_justin]

Absolutely agree with Corey (BlackGMC). Timing is WAY too high here and PE is not utilized properly. I understand the desire to lean the commanded afr out a bit, but this must be done only at light-moderate load. Leaning in PE mode will yield a significant power loss, and with the timing you're running, will also quickly lead to severe engine damage...

[BlackGMC]

Absolutely agree with Corey (BlackGMC). Timing is WAY too high here and PE is not utilized properly. I understand the desire to lean the commanded afr out a bit, but this must be done only at light-moderate load. Leaning in PE mode will yield a significant power loss, and with the timing you're running, will also quickly lead to severe engine damage...

What's up Justin? How was your trip to Texas? Sorry I did not get to meet up with you, while you were tuning Erics truck... Maybe next time..

[dc_justin]

What's up Justin? How was your trip to Texas? Sorry I did not get to meet up with you, while you were tuning Erics truck... Maybe next time..

Trip went well. Really wasn't much more that Eric's truck needed. Very stout setup given the mods and gearing. There will definitely be a next time.

[BlackGMC]

Trip went well. Really wasn't much more that Eric's truck needed. Very stout setup given the mods and gearing. There will definitely be a next time.

Yep he definately needs gears... Next time your in town you gotta let me buy lunch or dinner, something for all the help you have given me..

[Telco]

Yes, PE's already been adjusted, that's now an old file. Under PE I'm now anywhere from 12 to 13 to 1. Not really sure what the deal is on the timing because it's really not all that far off from what the factory tune had.

Yesterday I discovered that I can move the scan through one frame at a time (still learning the particulars of the program) and discovered that I'm seeing 99 percent of my knock retard on actual decel. Anytime the MAF detects a decrease in air, this is when I see the KR engage. Ran out of time to look yesterday, going to pick back up on it tonight and see if I can tweak it some more.

[BlackGMC]

Not really sure what the deal is on the timing because it's really not all that far off from what the factory tune had.

Can you post up your new tune and logs? There are 3 main tables that control the ending timing... HI octane, Lo octane, and Fuel mixture spark correction...

[Telco]

I'll try to get it on tonight.