black rich soot from pipe on WOT. Tune review request

[John377]

I have a 2002 2500HD 4x4 with specs below. It runs real good and the Lambda numbers on my gauge and logs seem OK but when I mash it on kick down I get black smoke out the pipes. The pipes are coated with soot. just to be clear it is not oil it is fuel. Can someone steer me in the right direction as to where I could have made a mistake in the tune. I attached my tune and a quick log with a downshift that blows black soot.

ls3 injectors
LSXRT intake
102mm TB
ls3 heads
04 LS6 cam
lQ9 shortblock
BBK headers
dual 3" exhaust
Map sensor 1264428

[danmw2003]

Just a guess here, but probably in your transient fueling tables. I'm a bit of a noob myself, so I couldn't tell you how to adjust them.

[kevin87turbot]

It's detonation. You have way too much timing in it. I'd recommend pulling at least 5-6 degrees out of it at WOT. That'll add torque and will also prevent the smoking.

[Digital Corvette]

Just curious why there wouldn't be active KR if there was too much timing?

[John377]

It's detonation. You have way too much timing in it. I'd recommend pulling at least 5-6 degrees out of it at WOT. That'll add torque and will also prevent the smoking.

That's what I thought but its not detonation. I crept up on this timing and the soot never changes. I've reached knock and backed off. The motor runs strong with this timing. I started with 25 at WOT and it starts to knock at 32.

[John377]

Just a guess here, but probably in your transient fueling tables. I'm a bit of a noob myself, so I couldn't tell you how to adjust them.

I did find and article about this and found the math to determine the min fuel in transient. It was different from what I had so Ill give it a try.

[kevin87turbot]

I don't doubt that it doesn't show knock until 30 degrees, but I typically see the power fall off around 28 degrees on the L76/L96 and LS3 combos with stock compression like yours.
On my old V-max truck, I had the same combo as yours, but a little larger Comp Cams camshaft. I ended up with 23.5 degrees timing at peak torque (around 4800 rpm) and around 25.5 degrees timing at 6000 rpm. It made the same peak power from 26-27 degrees at peak hp. It would start losing power at 28 degrees and lost even more at 29 degrees (lost around 6 hp at 29 degrees.) I never tried 30 degrees with it. It was on 93 octane only.

On my Pontiac G8, it would actually make peak power at 27 degrees. It made nearly the same at 28 degrees. (within 1 hp). It would fall off 4-5 hp at 29 degrees.

I'm not saying you're wrong, but I've dyno tuned 41 rectangular headed combos on the last couple years, and they nearly always make peak power on 93 octane from 25-27 degrees. The only exception that I can recall are a couple of lower compression combos that I tuned. They seems to like a couple extra degrees. It may not be the case with yours, but I just want you to keep it safe, and not give up any hp with your tune. If it does detonate at all, you'll always see it puff smoke...

If it's a transient fueling issue, you'll see a little rich spike on your wideband. I didn't notice that on your datalog.

I suppose that you might have one or two injectors that flow more than the rest. I've caught that issue on the injector flow bench a couple times. If this is the case, it will show up on your plugs as well.

On an unrelated topic, does your transmission shift really hard? I just saw that you're tuning in SD mode, but didn't delete the Trans Diag codes...that typically results in max transmission line pressure.

[John377]

I don't doubt that it doesn't show knock until 30 degrees, but I typically see the power fall off around 28 degrees on the L76/L96 and LS3 combos with stock compression like yours.
On my old V-max truck, I had the same combo as yours, but a little larger Comp Cams camshaft. I ended up with 23.5 degrees timing at peak torque (around 4800 rpm) and around 25.5 degrees timing at 6000 rpm. It made the same peak power from 26-27 degrees at peak hp. It would start losing power at 28 degrees and lost even more at 29 degrees (lost around 6 hp at 29 degrees.) I never tried 30 degrees with it. It was on 93 octane only.

On my Pontiac G8, it would actually make peak power at 27 degrees. It made nearly the same at 28 degrees. (within 1 hp). It would fall off 4-5 hp at 29 degrees.

I'm not saying you're wrong, but I've dyno tuned 41 rectangular headed combos on the last couple years, and they nearly always make peak power on 93 octane from 25-27 degrees. The only exception that I can recall are a couple of lower compression combos that I tuned. They seems to like a couple extra degrees. It may not be the case with yours, but I just want you to keep it safe, and not give up any hp with your tune. If it does detonate at all, you'll always see it puff smoke...

If it's a transient fueling issue, you'll see a little rich spike on your wideband. I didn't notice that on your datalog.

I suppose that you might have one or two injectors that flow more than the rest. I've caught that issue on the injector flow bench a couple times. If this is the case, it will show up on your plugs as well.

On an unrelated topic, does your transmission shift really hard? I just saw that you're tuning in SD mode, but didn't delete the Trans Diag codes...that typically results in max transmission line pressure.

I really appreciate the input and Ill give your suggestion a try. As far as the transmission; it shifts firm but not really hard. what does disabling the diag codes do?

[kevin87turbot]

When you fail the MAF sensor and tune in SD mode, you'll want to go to the transmission diag tab and disable the three MAF DTC's. If you don't, it'll max the transmission line pressure and quickly wear out the transmission pump.

HP Tuners Trans Diag.jpg

[John377]

When you fail the MAF sensor and tune in SD mode, you'll want to go to the transmission diag tab and disable the three MAF DTC's. If you don't, it'll max the transmission line pressure and quickly wear out the transmission pump.

HP Tuners Trans Diag.jpg

I did not know that, thanks.

The more I thought about it im not sure if this is a bad thing. Ive been running this big truck hard since 2003 with a turbo SD tune and with the trans set this way. I did 252,000 miles mostly towing before I threw a new motor in it this year, When I did the change I did a new converter and serviced the transmission. When I pulled the pan the fluid looked like I put it in a week before, it had about 90k on it since last fluid only change. Not a drop of clutch material in the pan, perfectly clean.