anyone see why it's missing on this log?

[camcojb]

I'm about at the end with this project. 05 GTO twin turbo with 402 LS2, 11 degree ET heads, and 15 psi twin turbo.

This is the last log I did today. At 14-15 psi it misfires pretty good at wot, yet I can't see the reason. I know the duty cycle is high, but the fuel pressure is steady, boost is steady, maf HZ don't break 14000 HZ. A/F is 11.9 and very steady, yet it's missing. At 12-13 psi it does not.

Any ideas? I have the 15000 patch, all the normal DTC's shut off, etc. Tried TR6's and BR7's at .030-.032". Runs fine at 12 psi or so but won't handle any more boost.

Jody

[EC_Tune]

Look at frames 142 to 143. Commanded AFR goes from 9.5 AFR to 13.4 AFR. Is COT turned off? How about P0068 error checking? <---8000 RPM fixes that...

[camcojb]

Look at frames 142 to 143. Commanded AFR goes from 9.5 AFR to 13.4 AFR. Is COT turned off? How about P0068 error checking? <---8000 RPM fixes that...

Never noticed that. COT is disabled and P0068 is set to 8000 rpms. Of course, it's misfiring throughout the wot range at that boost level, but what caused the commanded afr to change?

Jody

[EC_Tune]

Wierd... Haven't seen one drop the AFR like that. Especially with all the usual suspects turned off.
Maybe Chris has an idea.

Got an idea for the misfire.
Let's increase your Spark Dwell like this:

26.39844 19.96875 14.27344 11.10156 10.07813 8.03906 7.08594 6.50781 6.07031 5.81250 5.78125 5.75000 5.71875 5.69531 5.66406 5.63281 5.60156
26.39844 19.96875 14.27344 11.10156 10.07813 8.03906 7.08594 6.50781 6.07031 5.81250 5.78125 5.75000 5.71875 5.69531 5.66406 5.63281 5.60156
26.39844 19.96875 14.27344 11.10156 10.07813 8.03906 7.08594 6.50781 6.07031 5.81250 5.78125 5.75000 5.71875 5.69531 5.66406 5.63281 5.60156
26.39844 19.96875 14.27344 11.10156 10.07813 8.03906 7.08594 6.50781 6.07031 5.81250 5.78125 5.75000 5.71875 5.69531 5.66406 5.63281 5.60156
26.39844 19.96875 14.27344 11.10156 10.07813 8.03906 7.08594 6.50781 6.07031 5.81250 5.78125 5.75000 5.71875 5.69531 5.66406 5.63281 5.60156
26.39844 19.96875 14.27344 11.10156 10.07813 8.03906 7.08594 6.50781 6.07031 5.81250 5.78125 5.75000 5.71875 5.69531 5.66406 5.63281 5.60156
19.64844 15.81250 12.38281 10.40625 9.60938 7.94531 7.08594 6.50781 6.07031 5.81250 5.78125 5.75000 5.71875 5.69531 5.66406 5.63281 5.60156
14.89063 12.60938 10.56250 9.29688 8.68750 7.75781 7.08594 6.50781 6.07031 5.81250 5.78125 5.75000 5.71875 5.69531 5.66406 5.63281 5.60156
11.72656 10.24219 8.90625 8.03906 7.59375 7.10938 6.63281 6.14844 5.99219 5.81250 5.78125 5.75000 5.71875 5.69531 5.66406 5.63281 5.60156
8.58594 7.85938 7.19531 6.71875 6.40625 6.03906 6.26563 6.01563 5.92188 5.81250 5.78125 5.75000 5.71875 5.69531 5.66406 5.63281 5.60156
6.08594 6.05469 6.02344 5.99219 5.96875 5.93750 5.90625 5.87500 5.84375 5.81250 5.78125 5.75000 5.71875 5.69531 5.66406 5.63281 5.60156
5.79688 5.78125 5.75781 5.74219 5.71875 5.70313 5.68750 5.66406 5.64844 5.63281 5.60938 5.59375 5.57813 5.55469 5.53906 5.51563 5.50000
5.50000 5.50000 5.50000 5.50000 5.50000 5.50000 5.50000 5.50000 5.50000 5.50000 5.50000 5.50000 5.50000 5.50000 5.50000 5.50000 5.50000
5.50000 5.50000 5.50000 5.50000 5.50000 5.50000 5.50000 5.50000 5.50000 5.50000 5.50000 5.50000 5.50000 5.50000 5.50000 5.50000 5.50000
5.50000 5.49219 5.48438 5.48438 5.47656 5.46875 5.46094 5.45313 5.45313 5.44531 5.43750 5.42969 5.42188 5.41406 5.41406 5.40625 5.39844
5.20313 5.18750 5.17969 5.16406 5.15625 5.14063 5.12500 5.11719 5.10156 5.08594 5.07813 5.06250 5.04688 5.03906 5.02344 5.01563 5.00000
3.92188 3.90625 3.90625 3.87500 3.82813 3.78125 3.73438 3.68750 3.64063 3.59375 3.54688 3.48438 3.42969 3.37500 3.32031 3.26563 3.22656
2.63281 2.63281 2.62500 2.57813 2.50000 2.42188 2.33594 2.25781 2.17969 2.09375 2.00781 1.90625 1.81250 1.71094 1.61719 1.51563 1.45313
2.39063 2.39063 2.38281 2.34375 2.27344 2.20313 2.13281 2.06250 1.99219 1.91406 1.83594 1.74219 1.65625 1.57031 1.48438 1.39063 1.33594
2.15625 2.15625 2.14844 2.10938 2.04688 1.99219 1.92969 1.86719 1.79688 1.73438 1.66406 1.58594 1.50781 1.42969 1.35156 1.27344 1.21875
1.98438 1.98438 1.97656 1.94531 1.89063 1.83594 1.78125 1.72656 1.66406 1.60938 1.53906 1.46875 1.39844 1.32031 1.25000 1.17969 1.13281
1.89063 1.89063 1.88281 1.85156 1.79688 1.74219 1.68750 1.63281 1.58594 1.53125 1.46875 1.39844 1.32813 1.25781 1.19531 1.12500 1.08594
1.78906 1.78906 1.78906 1.75781 1.70313 1.65625 1.60156 1.55469 1.50000 1.45313 1.39844 1.32813 1.26563 1.20313 1.13281 1.07031 1.03125
1.69531 1.69531 1.68750 1.66406 1.61719 1.57031 1.51563 1.46875 1.42188 1.37500 1.32031 1.25781 1.19531 1.14063 1.07813 1.01563 0.97656
1.59375 1.59375 1.59375 1.56250 1.52344 1.47656 1.42969 1.39063 1.34375 1.29688 1.25000 1.18750 1.13281 1.07813 1.02344 0.96094 0.92969
1.50000 1.50000 1.50000 1.46875 1.42969 1.39063 1.34375 1.30469 1.26563 1.21875 1.17188 1.11719 1.06250 1.01563 0.96094 0.90625 0.87500
1.45313 1.45313 1.44531 1.42188 1.38281 1.34375 1.30469 1.25781 1.21875 1.17969 1.14063 1.07813 1.03125 0.98438 0.92969 0.88281 0.85156
1.45313 1.45313 1.44531 1.42188 1.38281 1.34375 1.29688 1.25781 1.21875 1.17969 1.14063 1.07813 1.03125 0.97656 0.92969 0.88281 0.85156
1.45313 1.45313 1.44531 1.42188 1.38281 1.34375 1.29688 1.25781 1.21875 1.17969 1.14063 1.07813 1.03125 0.97656 0.92969 0.88281 0.85156
1.45313 1.45313 1.44531 1.42188 1.38281 1.34375 1.29688 1.25781 1.21875 1.17969 1.14063 1.07813 1.03125 0.97656 0.92969 0.88281 0.85156
1.45313 1.45313 1.44531 1.42188 1.38281 1.34375 1.29688 1.25781 1.21875 1.17969 1.14063 1.07813 1.03125 0.97656 0.92969 0.88281 0.85156
1.45313 1.45313 1.44531 1.42188 1.38281 1.34375 1.29688 1.25781 1.21875 1.17969 1.14063 1.07813 1.03125 0.97656 0.92969 0.88281 0.85156
1.45313 1.45313 1.44531 1.42188 1.38281 1.34375 1.29688 1.25781 1.21875 1.17969 1.14063 1.07813 1.03125 0.97656 0.92969 0.88281 0.85156

Then set dwell Multiplier to 1.0 across the board.
The LS2 doesn't have a multiplier vs MAP (that I'm aware of) so you could probably go a little hotter than the above values for your TT setup. It will make the spark a lot hotter for the boost you are making.

EC

[camcojb]

Then set dwell Multiplier to 1.0 across the board.
The LS2 doesn't have a multiplier vs MAP (that I'm aware of) so you could probably go a little hotter than the above values for your TT setup. It will make the spark a lot hotter for the boost you are making.

EC

Well, thank you very much sir, it's worth a try.

Jody

[EC_Tune]

Can't wait to hear what happens!

EC

[redhardsupra]

you're out of injectors at any moment you get on boost really. by 5500rpm you're completely tapped out.
so you might be misfireing cause the fuel delivery is simply patchy at best. what injectors are these?

[camcojb]

you're out of injectors at any moment you get on boost really. by 5500rpm you're completely tapped out.
so you might be misfireing cause the fuel delivery is simply patchy at best. what injectors are these?

I know that also. These are 60's, I have a set of 75's also, but there aren't any real numbers to use them for the computer as GM doesn't have a proper scale for them. I tried them early on in the tuning and never did get a handle on making them run right, but I had other tuning issues back then also.

Jody

[PurplePiss]

Is it possible he's blowing the spark out?

[redhardsupra]

I know that also. These are 60's, I have a set of 75's also, but there aren't any real numbers to use them for the computer as GM doesn't have a proper scale for them. I tried them early on in the tuning and never did get a handle on making them run right, but I had other tuning issues back then also.

Jody

well, then how do you expect a steady, proper fueling? you can't really predict fuel delivery once you go past 80-85% duty cycle on injectors. so if you wanna continue tuning, i'd turn the boost down as much as possible, get everything in line, and then put in bigger injectors and figure them out.
i have a bunch of logs (both hpt and dyno sheets) where you can see correlating high duty cycle and fluttering power. i'd avoid that at all cost, especially under boost.

[camcojb]

well, then how do you expect a steady, proper fueling? you can't really predict fuel delivery once you go past 80-85% duty cycle on injectors. so if you wanna continue tuning, i'd turn the boost down as much as possible, get everything in line, and then put in bigger injectors and figure them out.
i have a bunch of logs (both hpt and dyno sheets) where you can see correlating high duty cycle and fluttering power. i'd avoid that at all cost, especially under boost.

I understand duty cycle. It has never exceeded 85% until that datalog. Problem is there's no big HP fuel systems for the GTO's, so I'd have to make my own system, surge tank, etc.

I came up with a much simpler solution. I am just finishing putting the car back to stock and it's going to be sold along with all the mods separately. I made a mistake doing this build as there's too many weak links on this car with big power, and I am tired of putting money into it. Couple that with the maf tuning issues with 700+ rwhp and it's just not worth it to me. After the fuel system the rear end will go, then something else, so on and so on.

The engine and turbo system are capable of 1000 HP but I'm limited to much less at this point, and I don't like that. Appreciate the help guys, it's been fun, but at this point there isn't any big hp tuning available for the LS2's other than aftermarket, which is not a direction I want to go on this new car.

Jody