2004 6.0 NV4500 Tahoe

[Dantheman1540]

Tonight was my first time really getting on it since I did the heads and although it has an exhaust leak and isn’t really done being tuned, it feels much better midrange and definitely up top! The maf fueling looks great +/-3% and it seems to love 23* of timing. After I finish fuel tuning I can’t wait to sprinkle a little more timing and see what it does.

It actually spun on the 1-2 shift long enough I peddled it which it’s never done on dry pavement.

 

[iamdub]

Tonight was my first time really getting on it since I did the heads and although it has an exhaust leak and isn’t really done being tuned, it feels much better midrange and definitely up top! The maf fueling looks great +/-3% and it seems to love 23* of timing. After I finish fuel tuning I can’t wait to sprinkle a little more timing and see what it does.

It actually spun on the 1-2 shift long enough I peddled it which it’s never done on dry pavement.

Mine's at 24° (on 93, 10.25 SCR)

 

[Dantheman1540]

Mine's at 24° (on 93, 10.25 SCR)

Before at 10.9cr & 21-22* it had what I thought was false KR in weird spots including right at the top but I thought it was related to the shifts. I did a bunch of spark table smoothing and upped it to now 23* with 10.5cr and it has absolutely zero KR anywhere and genuinely feels more lively. I’ve seen some people seeing 26-28* making Mac power with somewhat similar cams in ls2s so I’ll try to sneak a little more in there later and see how it feels.

 

[Dantheman1540]

I make sure to keep the low octane table 4* or more below the high in case it does sense KR.

 

[iamdub]

Before at 10.9cr & 21-22* it had what I thought was false KR in weird spots including right at the top but I thought it was related to the shifts. I did a bunch of spark table smoothing and upped it to now 23* with 10.5cr and it has absolutely zero KR anywhere and genuinely feels more lively. I’ve seen some people seeing 26-28* making Mac power with somewhat similar cams in ls2s so I’ll try to sneak a little more in there later and see how it feels.

I'm kinda feeling that my 24° might be safer than I thought. Instead of trying to max out the timing to the ragged edge on 93, I'm gonna try 90 octane (50/50 mix of 89 and 91) and work down from there.

 

[Dantheman1540]

I'm kinda feeling that my 24° might be safer than I thought. Instead of trying to max out the timing to the ragged edge on 93, I'm gonna try 90 octane (50/50 mix of 89 and 91) and work down from there.

Do you know what your low octane spark table is set to? I ran 87 with the previous setup but only during a long road trip that was a steady cruise for two tanks.

 

[iamdub]

Do you know what your low octane spark table is set to? I ran 87 with the previous setup but only during a long road trip that was a steady cruise for two tanks.

24°. Just ramps up more sharply on high octane. Unless we're looking at two different things.

I could probably run 87 on a road trip if I could ensure that I wouldn't go WOT.

 

[Dantheman1540]

24°. Just ramps up more sharply on high octane. Unless we're looking at two different things.

I could probably run 87 on a road trip if I could ensure that I wouldn't go WOT.

There's a high octane table which is what the truck will start with and stick with unless KR is recorded then it will pull timing and possibly revert to the low octane table of the KR is consistent. Typically a good tuner will take the high octane table paste it onto the low table and then subtract X amount of timing across the board to keep stuff safe in the event you get KR or decide you want to run cheaper fuel which I will be doing after I get the tune sorted.

 

[Dantheman1540]

Very frustrated with this idle surging, sometimes it idles flawless then other times it drops into this crazy sawtooth pattern where timing can jump from 29* to 15* I've already made fairly large changes to the overspeed/underspeed tables trying to keep the spark from over correcting itself and the spark table is very smooth and gentle, especially in those areas and the surrounding cells.

I'm gonna go back to adjusting base idle airflow and see if that's part of the problem. The white sawtooth pattern is the spark advance.

 

[Dantheman1540]

I think I partially figured the idle out, the base idle airflow need about a 50% increase which seems crazy when keeping the same cam. Guess these heads really flow a ton.