2008 LS2 - E67 - TVS1900 - 4L70E - Tuning Tips Needed!

[griffincox]

I have a 2008 AWD Trailblazer SS with a totally stock engine (top and bottom end) and a TVS1900 with 2.9" Diameter pulley, GM 50#/hr injectors (12613412), LS2 Car throttle body (4" diameter fender well intake), LS3/7 MAF, 3 Bar Bosch MAP, 1-3/4" long tube headers with dual 2.5" exhaust, NGK TR6 plugs (.035" gap), plug wires, etc.

I have a few questions related to the engine tuning process. I have searched tirelessly on these issues with very little overall luck.

A few things to keep in mind:

- I live in Denver and the average barometric pressure I see on my MAP is about 82-84 kPa vs many areas 98-100+ kPa. What this means is that nearly the first 3 psi of "boost" are just to make up for the big disadvantage up here (for the racers here, 7000-9000 DA is common)

- The best pump gas I can get here is 91 AKI with "up to 10% ethanol" or 91 AKI with 0% ethanol ($$$). Id like to be able to just pump 91 in and drive it.

- The maximum boost pressure I see is about 135-140 kPa which is 7.8 PSI above atmosphere here or about 5.5 to 6psi at sea level.

- I am tuning in open loop speed density right now with lambda error plotted. I have a NGK AFX wired to my MPVI Pro.

So, a few questions:

- How do those of you with automatic transmission drive the vehicle to tune? Do you select a specific gear and hold it to get into the high load/low RPM and low load/high RPM areas to cover the entire VE table (or as much as you can cover). Driving under normal conditions when the TCM is picking gears the vehicle will never see these conditions (top right and bottom left of your typical VE table), correct? Its also very hard to capture wide open throttle data because you get so few data points per pull. Do you guys just do a lot of WOT runs?

- I am getting quite a bit of knock retard. I need to burn up what is left in my tank and put some fresh 91 AKI in to verify the fuel is "good". But one thing I have been able to find very little info on, is typical spark advance for positive displacement superchargers like the TVS1900. It obviously needs to be a lot less than a naturally aspirated vehicle but are we talking single digits, low teens, high teens? You will see in the log I am getting KR at typically around 12-18* of advance. Also a lot during throttle transients which brings me too...

- I have some transient fueling issues. I have read everything I could find on this and have made some changes to the tune that I need to test. If anyone has tips on transient fueling as it pertains to a TVS1900 let me know. This thing builds boost immediately so the transient fueling is very important. I have basically increased the fraction of fuel that will evaporate from the port walls slightly, and then more aggressively increased the fraction of fuel that impacts the port wall, particularly in the high MAP regions.

Those are pretty much my main 3 concerns. Find attached: a Log (look at 2:10 to find a WOT run) and Stock and Current Tune. Any insight or experience anyone has to share would be appreciated.

I am all ears.

-TBSS - TVS1900 - SD OL.hpl
-TBSS - TVS1900.hpt
-TBSS - Stock.hpt

[griffincox]

Bump. Anyone have any insight?

I also have a cold start issue. It cold starts super lean. CMD lambda starts at about .84-.85 and then climbs to 1.0 as coolant gets to around 90* F. But the actual lambda is beyond what my NGK AFX can read (16.00 AFR/~1.08 lambda). Once warm and on warm starts, idle seems to hover near 1.0. Could this be related to the VE table or injector data or something else. The computer commands the correct lambda but does not fuel for it. So it either is wrong with fuel or air or both.

[griffincox]

It also seems that PE is enabling after some type of delay. I have RPM Delay Set to zero. TPS is low and MAP is low as well (70 kPa Currently). I sometimes don't see PE enable until about 95-105 kPa. Is there some missing tables for an '08 TBSS? Another explanation?

Anyone have any feedback on any of the above?

[kelleyperformance]

shoot me an email, be glad to help you out

[email protected]

[griffincox]

Well, over the course of many months, hours of reading, learning and doing, I am close. Thanks to all that have contributed to this forum and the much larger pool of info out in the world wide web. I have dialed in MAF, SD, transient, cold, warm, etc. Just a few days ago I went ahead and put the engine control back into dynamic air calc mode with closed loop with STFT enabled, LTFT disabled. I have been driving it to work, mostly light cruise, highway stuff. I went WOT a couple days ago, everything good to go. Went WOT just a few minutes ago and felt something very worrying that the log confirmed. Basically at 3 different areas, actual lambda strayed very far from commanded, from what appears to be the injectors not cooperating. This appears to stem from the cylinder airmass not being calculated correctly. I probably need to log a few different PID's like Air-calc mode, etc. Anyway, please review tune, log and image. Looking at frame 6200-6400. Whats going on here???? This is downright dangerous for the motor I am sure. Never saw anything like it in OL-SD, OL- MAF, etc.

Screen Shot 2014-10-22 at 1.28.20 PM.png

Latest Tune.hpt
Latest.hpl

[griffincox]

Well, more info. Of course I didn't check codes after the event. Checked now and there were two immature. As i drove home i went into boost once more P0121 matured and immediately lit the MIL light for P0121. I also saw this code a few weeks ago while in SD-OL after stabilitrak activation.

Thoughts? Throttle body acting up?


[] P0121 - Throttle/Pedal Position Sensor A Circuit Range/Performance (SES) (Pending) (History) (Immature)
[] P1101 - Mass Air Flow Sensor Out Of Self Test Range (Immature)
[] P0121 - Throttle/Pedal Position Sensor A Circuit Range/Performance



Edit: The new log, also another attached image. Look at dynamic air dip far below either MAF or VE. WTF is going on here?

Screen Shot 2014-10-22 at 4.39.19 PM.png

Latest2.hpl

[sssnake]

I saw that you selected torque management > supercharger > supercharger torque management > supercharger > not fitted which you would think would disable all of the supercharger related torque management but... You are awful close to the torque management > supercharger > boost disable > map enable value of 140 KPa. I would bump that value to 175 lather, rinse, and repeat. I think that will help on the cyl air situation.

I haven't had difficulties with any of these codes (so I have very little experience with them) but I would see if I could get the cyl air issue fixed before plowing into the trouble codes (they may all be related to the cyl air issue). Good luck!

I forgot to mention that I would bump the map disable by a corresponding amount.

[griffincox]

I saw that you selected torque management > supercharger > supercharger torque management > supercharger > not fitted which you would think would disable all of the supercharger related torque management but... You are awful close to the torque management > supercharger > boost disable > map enable value of 140 KPa. I would bump that value to 175 lather, rinse, and repeat. I think that will help on the cyl air situation.

I haven't had difficulties with any of these codes (so I have very little experience with them) but I would see if I could get the cyl air issue fixed before plowing into the trouble codes (they may all be related to the cyl air issue). Good luck!

I forgot to mention that I would bump the map disable by a corresponding amount.

Thanks for the help!

All of the settings in the Torque Management > Supercharger area are stock/OE settings for my 2008 TBSS. Those have been unchanged since the beginning. I think the change in cylinder air may be actually happening... The throttle body code has me suspicious of it being fully functional... Truck has been running on this TB and setup for over a year now. Just recently have I started having some issues. And they all seem to be related to the TB. A violent closure of the TB occurred when stabilitrak activated at WOT and now I have seen the code twice since. I am using the early car throttle body now (~05-08, LS cars, silver blade). Considering replacing the throttle body with a late (09+) car, or the 2009+ Car/truck that is used on the 2009 TBSS, 2009+ CTS-V and ZR-1, as well as many full size trucks and others. First I will inspect the wiring and throttle body though. I am leaning towards a hardware failure if you can't tell...

Anyone with further thoughts?

[sssnake]

Understood but... My suggestion is cheap and quick.

You said you left all of these settings stock. Gotcha. So in a stock engine you will never reach the 140 KPa (no blower). You added a TVS 1900 blower. Tuned the car but left this section untouched. Now the engine can reach well over atmospheric pressure. The weather has cooled off lately, which tends to increase boost at bit (more efficient because air is colder/denser). So now you are hitting a MAP pressure level that approaches activation of some control code on the ECM. If fuel cut is one of the boost limiters the ECM uses then you would get what I see in your log.

I am almost tempted to lower mine and go out and log to see what happens

I forgot to mention that the CST V2 guys were having issues with this parameter when upping the boost. They are on a stock blower (obviously) so the situation is different but when I look at the menu structure it looks like this would be an active parameter even if the supercharger not fitted option was selected. Just hard to tel without having access to the ECM source code and looking at the branch logic.

[griffincox]

Understood but... My suggestion is cheap and quick.

You said you left all of these settings stock. Gotcha. So in a stock engine you will never reach the 140 KPa (no blower). You added a TVS 1900 blower. Tuned the car but left this section untouched. Now the engine can reach well over atmospheric pressure. The weather has cooled off lately, which tends to increase boost at bit (more efficient because air is colder/denser). So now you are hitting a MAP pressure level that approaches activation of some control code on the ECM. If fuel cut is one of the boost limiters the ECM uses then you would get what I see in your log.

I am almost tempted to lower mine and go out and log to see what happens

I forgot to mention that the CST V2 guys were having issues with this parameter when upping the boost. They are on a stock blower (obviously) so the situation is different but when I look at the menu structure it looks like this would be an active parameter even if the supercharger not fitted option was selected. Just hard to tel without having access to the ECM source code and looking at the branch logic.

Agreed. Ill up it just to rule it out. I also adjusted ETC Area Scaler to match other vehicles with this throttle body: 4,725.00. I had overlooked this before. The TBSS had 4,552.25.

I also disabled fuel cut in a few things that should have no effect, but to be safe. (Supercharger torque boost limit, Powerhop, etc)

Anyone seen P0121 be related to software vs hardware vs...?

[griffincox]

I was trying to avoid this, but it sounds like this may be something I just have to disable...

http://www.hptuners.com/forum/showth...fety-mode-quot

I would like to avoid disabling this safety feature if possible.

[griffincox]

Okay, so I disabled the 3 tests under airflow diagnostics, and set the temp for the P0101, P0106, P0121 tests to max -40 and min to 493. That cured the DTCs at WOT as expected and also any odd throttle behavior or jerkiness. But I still have a major issue. In open loop PE, lambda does not match commanded in some (many) areas. In open loop SD, and open loop MAF during calibration everything was +/- 0-3% in all areas. Now in Normal/Dynamic, not the case. It strays upwards of 20-30% lean. It seems that Dynamic Air is being calculated correctly (hovers around same values as MAF and VE), but fuel flow doesn't follow.

I changed transients back to stock values to rule that out. The only other ideas I have had, but not tested, are changing the stoich AFR from 14.3 to stock at 14.7. Also, I changed my prediction coefficients in Airflow>Dynamic>Prediction Coefficients to ZL-1 numbers from the stock TBSS LS2 numbers (they are dramatically different). Could this be the cause? I will change these two things and test again. I want to get this figured out as running lean in boost is not something to play around with.

Please help me solve this!

Latest Tune and Log:
Quick Test.hpl
Latest.hpt

[griffincox]

Well, I believe I solved the problem I was having by zero'ing out all 10 Prediction Coefficient tables (I had ZL-1 data in these tables, which in hindsight was not a good idea). This leads me back to a thread I started months ago. It sounds like very little is known about these tables, at least mathematically. Unfortunately I am not good enough with math to make sense of em, but hopefully sometime soon one of you wizards can make sense and use of what seems to be some powerful variables in the OS for predicting airmass.

http://www.hptuners.com/forum/showth...n-Coefficients