Need help with twin turbo LS2 tune

[QuickSilver2002]

What I do not understand is how halving the VE table helps on an LS2 at all. It doesn't use it with the MAF. I thought when the maf runs out, and if it doesn't fail it goes to the PE table, not VE table for fuel.

Jody

Jody,
They are talking about forcing the car into SD and running a 2bar MAP sensor without a 2bar os. It can probably be done, but it requires a bunch of tricks to figure out what you are doing. You loose lots of granularity and I honestly think you will be better off with a MAF on a car where you don't play with the boost controller too much. SD is great and all, but I don’t think it is worth it without the OS modified to have the extended map values in it.

Just to clarify, when the maf runs out it does not switch to the PE table. The PE table is always in play, it is what determines the demanded AF ratio (via the EQ) when in power enrichment mode. So when the maf runs out you use the PE table to demand progressively higher EQ values as the RPMs go up.

demanded AF = 14.7/EQ

So once the maf hits the last cell in the maf table (at lets say 5k), your PE vs RPM table will start ramping up the EQ ratio at a pretty aggressive rate. This will result in extremely low demanded AF ratios, but the resultant AF can be whatever you want. I could dig up some old examples from my blower car when I had a maf on it if you need to see that.

The thing you have to be careful about with this approach is boost spikes or any other dramatic changes in your setup. The tune ends up being pretty much hard coded once in that area where the maf is static. Most people just go real conservative to allow for plenty of wiggle room. You can get aggressive as you want on the dyno, but I personally dial it back to be fairly conservative unless I’m monitoring things very closely.

[camcojb]

Got it and thanks. I'm going to continue this way for now, that sounds like it's a bit tricky. My boost has been incredibly steady throughout this, so hopefully that will continue.

Jody

[camcojb]

Okay, caught a bit of dry weather so I went out to see if the changes made a difference. Now I can go 12 psi without issue. I was lean, so I changed my PE table where it was pegging the maf and took a shot as far as how much richer to go. First try hit 12.0 A/F in top gear at wot.

This is on the 8:1 402 so 12 psi is not pushing it at all. I can say though that even with the 285 dr's a downshift to second at 50 mph (auto trans) will spin the dr's; first time I did it the car went sideways. It's never done that before with the drag radials.

The changes that worked were setting the maf fail point to 16384 which is as high as it can go. The 15000 HZ patch stops reading beyond that and so you adjust your PE tables from the point you max the maf and set the A/F that way with a wideband. Biggest issue is you'll probably need a different tune for different boosts, but once you set them all you're set. My thoughts are this will work fine until HPTuners can do a SD 2 bar setup for the LS2's. And I don't change the boost very often. I'll find a level that keeps me happy and stick with it.

I am going to swap springs in the boost actuators to try 14 psi just to see how it reacts. Thanks again for all the help guys.

Jody

[EC_Tune]

Glad to hear you are getting this sorted out Jody!
Keep us all up to date!

EC

[2xLS1]

Did your's ever go into Reduced Power mode during all of this?

[camcojb]

Did your's ever go into Reduced Power mode during all of this?

Absolutely, until I put the 15000 HZ patch in correctly and raised the maf limit.

Jody

[2xLS1]

Absolutely, until I put the 15000 HZ patch in correctly and raised the maf limit.

Jody

I've got a 05 GTO with a STS Turbo kit (7~8 psi max) still going into Reduced Power mode even after those 2 fixes were put in. Any ideas what else to change to keep it from doing this? It's also setting a code. I'll know what the code is in a couple hours when they bring the car back to me. We had the car on the dyno for 12 pulls and several WOT blasts on the street and it didn't do it. Thought it was fixed. As soon as the car was taken back to the owner, it popped up again.

[camcojb]

I've got a 05 GTO with a STS Turbo kit (7~8 psi max) still going into Reduced Power mode even after those 2 fixes were put in. Any ideas what else to change to keep it from doing this? It's also setting a code. I'll know what the code is in a couple hours when they bring the car back to me.

Are you positive the patch is in? Go into your tune and click on the HP OS symbol at the upper left and see if it shows patched 15000 or still shows unpatched 11500. When tuning you load calibration changes only, but for this patch to work you have to "write entire" tune, not just cal changes. I didn't do that and the patch won't work.

If the patch is in correctly also go to engine diag and make sure the maf fail is set to 15000-16384.

If these aren't the issue you need to post a datalog and see if we can pick something else wrong.

Jody

[2xLS1]

Are you positive the patch is in? Go into your tune and click on the HP OS symbol at the upper left and see if it shows patched 15000 or still shows unpatched 11500. When tuning you load calibration changes only, but for this patch to work you have to "write entire" tune, not just cal changes. I didn't do that and the patch won't work.

If the patch is in correctly also go to engine diag and make sure the maf fail is set to 15000-16384.

If these aren't the issue you need to post a datalog and see if we can pick something else wrong.

Jody

I positive those 2 fixes are in. We couldn't run the car over 5.5K rpms without the A/F going way lean before I did those. A/F is fine up to 6.6K after I patched and changed the MAF fail freq. This thread really helped me figure out what was going on there. I just found out that just turning the car off and back on reset the Reduced Power error, but the SES is still on. I'll post up more after I read the code in a little while.

[2xLS1]

You can look here and see what the car did. We're real happy with the outcome except for this one last problem.
http://www.ls1tech.com/forums/showthread.php?t=514776

[2xLS1]

OK The code it set was P0068. Any problems with seting the enable P0068 test rpms to 8000 so the test never runs? I'm guessing this is what is triggering the Reduced Power mode. Should I also set the DTC to no error reported or would that even mater with the test enable set to 8000?

[camcojb]

OK The code it set was P0068. Any problems with seting the enable P0068 test rpms to 8000 so the test never runs? I'm guessing this is what is triggering the Reduced Power mode. Should I also set the DTC to no error reported or would that even mater with the test enable set to 8000?

Yes, set the P0068 t0 8000 rpms, I have that also. I assumed you had it shut off, sorry.

Jody

[2xLS1]

All I was able to try so far is the P0068 set to 8000. That seems to be working so far. Then I found post #6 in this thread. http://www.hptuners.com/forum/showth...ighlight=p0068 After seeing the other thread, I went to set the other test to not run and set P0068 to No Error Reported and my MPVI interface took a dump on me so I was not able to flash the other changes. Waiting to hear back from support to see what to do about the interface.