Suggestions for curing sluggish throttle response

[Joe_G]

These changes made a nice difference to me. I may try a little higher on the filter table values next time I play with it.

Excellent, thanks. Is this from a C6 Vette? What year?

You're showing the differences between two tunes. Would you mind too much showing your tune instead of the changes?

I'm assuming your changes displayed above are from stock... but I don't really want to make that assumption not knowing what year your car is and what tune you're comparing to.

Sorry to keep asking more or less the same question! But I sure appreciate your help.

[deanm11]

His car is a Trailblazer SS.

Bill- your screenshot shows negative values for enable delay and maximum mass ??!!

[Joe_G]

His car is a Trailblazer SS.

Bill- your screenshot shows negative values for enable delay and maximum mass ??!!

He's showing the differences between two tunes - look closely at the table he's showing. The "show changes" button is highlighted. That's why I asked my question above.

[deanm11]

He's showing the differences between two tunes - look closely at the table he's showing. The "show changes" button is highlighted. That's why I asked my question above.

Doh! Sorry. Didn't know that worked for the non-table values.

[BBA]

LOL...yep, that was the differences. Although now that I think about it I went a little across the range on the filters, instead of just the first four cells in the last tune I did.

The tune I was showing was my 2007 TBSS, which is why I showed the differences because my base values will mean very little to you for a different car. I did basically the same changes to the 2006 C6 with the same results.

[BBA]

Here is the C6 screenshot:

[Joe_G]

Here is the C6 screenshot:

Great, thanks!

Earlier you mentiomed to reduce the MAP filter from .25....but it's not changed. Is that an oversight or did you find that change not effective?

I'm loaded up and ready to test tomorrow, I'll post up my thoughts.

Thanks again!

[FraggerCrue]

One thing you have to keep in mind, that is a big cam (see this discussion link).

Regardless of tuning, it will always be sluggish at 2000 rpm. You also have 1 7/8 headers on a stock displacement LS2, which helps to kill your low end torque. To see this for yourself, take the car to the dyno and begin your pull at 2000 rpm. I bet you don't make good power until 4000+

The 3.90 gears should help a lot with the sluggishness, because of the greater torque multiplication and because they help you get into your power band more quickly.

[Joe_G]

One thing you have to keep in mind, that is a big cam (see this discussion link).

Regardless of tuning, it will always be sluggish at 2000 rpm. You also have 1 7/8 headers on a stock displacement LS2, which helps to kill your low end torque. To see this for yourself, take the car to the dyno and begin your pull at 2000 rpm. I bet you don't make good power until 4000+

The 3.90 gears should help a lot with the sluggishness, because of the greater torque multiplication and because they help you get into your power band more quickly.

Actually, if you look at my dyno sheet in post 13, my torque is more or less the the same as bolt on only down low. I'm not complaining about low end power at all, it's great. What I'm talking about is when you hit the gas with the clutch pushed in it takes a moment to rev up. Not a big deal except I like to go to HPDE and the slow response to hitting the gas pedal makes heel and toe shifting more difficult.

[BBA]

Joe: Map Filter...

It's still in my plans, but I haven't experimented that much with it so I don't want to post any specific settings to mislead anyone until I get a better feel for it.


So, how did your testing go?

[Joe_G]

Joe: Map Filter...

It's still in my plans, but I haven't experimented that much with it so I don't want to post any specific settings to mislead anyone until I get a better feel for it.


So, how did your testing go?

Well, made the changes yesterday and scanned my way to work. Car did seem a little more snappy with throttle response. Not night and day but better. Fuel trims were -2 to 0, so fueling must be very close. I'm going to scan again today and see how I'm doing.

[kenny c]

I also made some changes based off of the info in this thread. The SOTP dyno shows improvement, but how much I can't be sure.

Thanks for sharing all of this information!

[Joe_G]

I scanned to work again today - it feels snappier but I've learned to not really trust my STOP meter. Again, my fuel trims were really low - lower than normal (closer to 0).

I don't think these settings would lower the STFT and LTFT trim adjustments would they?

In summary, I'm liking the changes. I'm really looking for a change that as I think about it is a SOTP change - I want the car to rev up faster with the clutch in or in neutral, so this changes is working so far. I might increase the settings some and see if the effect gets more pronounced.

[BBA]

I scanned to work again today - it feels snappier but I've learned to not really trust my STOP meter. Again, my fuel trims were really low - lower than normal (closer to 0).

I don't think these settings would lower the STFT and LTFT trim adjustments would they?

In summary, I'm liking the changes. I'm really looking for a change that as I think about it is a SOTP change - I want the car to rev up faster with the clutch in or in neutral, so this changes is working so far. I might increase the settings some and see if the effect gets more pronounced.

I'm happy with mine so far as well, but I may go a little more too. Let us know what your final outcome is. I have an automatic, so the changes are not going to feel exactly the same as someone with an M6.

I can see it changing STFT a little, as in a good way because your getting less of an AFR under/overshoot on accelleration.

[5_Liter_Eater]

I made the changes BBA posted in the C6 screenshot above. I have to say I did notice the throttle being snappier. It also seemed like my low RPM/low throttle had more oomph, like it took less throttle to do the same thing than previously.

[Joe_G]

I made the changes BBA posted in the C6 screenshot above. I have to say I did notice the throttle being snappier. It also seemed like my low RPM/low throttle had more oomph, like it took less throttle to do the same thing than previously.

Hey Bill, did you notice any difference in your LTFT's being smaller?

[5_Liter_Eater]

Unfortunately I wasn't logging fuel trims with the config I was using.

Anyone tried disabling transient fueling alltogether?

[flea]

Great post, it's nice to see other people are having similar sucess modifying transient fueling using temp bias, etc.

http://www.hptuners.com/forum/showthread.php?t=13569

[Joe_G]

OK upped the settings a bit, the increase %are as shown below:

0

16

32

48

64

80

96

112

128

0.02807

0.02035

0.01099

0.00591

0.253

0.269

0.285

0.302

0.318

15%

10%

5%

3%

These settings seem good, I think I'll run with them for a while.

My LTFT's are really close to 0 now that I've made these changes - I wonder if these changes are affecting that??

Flea I don't have a wideband but I bet we were having the same exact problem! If feels like the accelerator pump is not working (back from my Holley/Quadrajet tuning days). These changes seem to have increased the "pump shot" a bit which is good.

[Kelp]

Joe: Map Filter...

It's still in my plans, but I haven't experimented that much with it so I don't want to post any specific settings to mislead anyone until I get a better feel for it.

So, how did your testing go?

Hi, I've been following this and applied these fuel transient and cylinder charge parameters tonight. Datalogged and noticed that cat-less smell is a little more tame. Throttle response seemed better, but I was also expecting it. The MAF increase was nearly instantaneous on the log, for sure. Overall, it drove smoother around the neighborhood.

What were your ideas with the "MAP Filter" parameter? I would try it, but don't know which way to adjust it.

I also kept my Delta TPS at 1, seemed ok there. Thanks for the good insights and applications.