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TrailblazerSS
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Discussion Starter · #1 ·
Is it torque management or the torque converter the reason why if I give it more than 1/8ish pedal off the line it completely dogs out of the hole? If I roll into it it's not as bad. I know a good converter wakes these up but the issue feels computer controlled to me. Its almost dangerous when trying to pull out in traffic and kills 60 foot time. I finally made it to the track and the best 60' I could pull is a 2.26. The one run I rolled into it too fast it crawled to an embarrassing 2.55! The SS is an '09 AWD with IEASTSRT8 intake, IAT relocating kit, Pypes muffler/res delete and SCT custom tune. Thanks
 

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2006 Red Jewel AWD
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11,641 Posts
Burst Knock...The stock tune in the ECM puls a shit load of timing as you wood the skinny pedal from idle. Then it slowly (milliseconds) reintroduces timing back into the program.
 

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Discussion Starter · #5 ·
Yes both traction control and stabilitrac were turned off. No spinning of the tires with AWD. It happens with both the stock tune and my SCT tune. I doubt its knock cause i threw in a few gallons of 100 octane to mix with my couple gallons of 93 just to be safe. Any other thoughts?
 

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'07 SS3 Silverstone
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Since I got tuned from Trent at Colorado Performance Unlimited, I haven't noticed that issue LOL. I hit it, and it responds. Is it as fast a response as I dreamed of? No, but for a DD it's something I will be happy with.

:cheers1:
 

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Discussion Starter · #7 ·
Maybe someone with a pcmforless tune or a professional tuner can chime in and shine some more light...
 

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Burst knock is the computer taking timing out to prevent knock, you could have 150 octane gas (large number for figurative purpose only) and if the conditions are met still see burst knock. Its a safety feature in the computer coding.

Second it could be the negative timing the stock tables have that for a fact SCT does nothing about.

There is a throttle limiter table that could be coming into play.

The 07+ has a tipin limiter as part of the TM system that causes a delay.

lastly if the truck is lean you will see a bog and if pretty safe to say if your using a base tune from SCT its not taking into account your intake system
 

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2006 Red Jewel AWD
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Yes both traction control and stabilitrac were turned off. No spinning of the tires with AWD. It happens with both the stock tune and my SCT tune. I doubt its knock cause i threw in a few gallons of 100 octane to mix with my couple gallons of 93 just to be safe. Any other thoughts?
You don't get what I am saying...Burst Knock Retard has nothing to do with what fuel you are using. It has to do with the program. And unless you have a custom tune with the Burst Knock tables set less aggressive and hurry the decay rate tables as well, you have no way of overcoming it.
 

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Discussion Starter · #11 ·
Ah thanks for clarifying that, makes sense now. SCT was throwing around the term "tipin" limiting or tipin tq when they were trying to figure out the initial torque management issues I was having. In case you missed my post awhile back the truck would load the tune fine, start fine but as soon as i pressed the gas in any forward gear it would kill the engine, in reverse it would not happen. I was their first '09 AWD and first one to have this issue. Its since been corrected but it could definitely use less aggressive burst knock tables and slower decay rate tables by the sound of what Evil SS has mentioned. SCTs been really helpful with me sending files back and forth working out any kinks so I'm hopeful they will take a look at the above mentioned tables. I told them about my minor mods during the tuning process so I'm hoping they've accounted for the intake etc. I plan on doing some data logging and reviewing the a/f and knock as well. Thanks to all for schooling me on the basic tuning involved with possibly correcting this issue.
 

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'07 awd
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:popcorn3:
 

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'07 awd
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Trailblazer SS AWD
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Give alvin a call. He'll set you up. Then get a new converter too. Cant wait to get mine in
 

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06 TBSS 2WD
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139 Posts
I struggled with the same thing for a long time. There are a number of reasons why these things are slugs out of the hole, but tuning can help.

One issue is burst knock. Tuning that out helped.

Another issue is timing tables. I had a mail order tune that had the timing pulled WAY back under 3k RPM's all around the KPa levels that you would see when opening the throttle all the way. My truck was way faster out of the hole with partial throttle because I had much more timing in higher vacuum. Under WOT my truck would fall on its face until 3k RPM's and then it would take off. That's because my timing jumped from 10 to 19 degrees. I cleaned up the timing tables and now have a much smoother transition.

The third issue I ran into was throttle delay. Disabling it makes a nice difference.

At the end of the day my TBSS is still a little doggy out of the hole by my standards, but that's just me. My first car was a '68 Buick GS with a built 455 Buick big block. That thing put out over 510 lb/ft of torque at only 2200RPM's. Talk about instant throttle response! My '06 Titan has lots of instant low end as well..especially with torque management completely disabled. It falls on its face over 5K though.
 
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