PCM Diagnostics & Tuning HP Tuners | Holley | Diablo

Help with hard dip and recover on the dyno

Thread Tools
 
Search this Thread
 
Old Mar 24, 2021 | 05:18 PM
  #1  
Hammer31's Avatar
Thread Starter
Teching In
 
Joined: Mar 2021
Posts: 20
Likes: 0
Default Help with hard dip and recover on the dyno

Have a 2007 Tahoe LT
BTR stage 2 new springs lifters pushrods
new built tranny with 2000 convert

I take it to the tuner and he gives me this and said I don’t know why it’s doing that.

I don’t have a ton of info but hoping someone has seen this before and can help. Thanks in advanced

Reply
Old Mar 26, 2021 | 12:31 PM
  #2  
Hammer31's Avatar
Thread Starter
Teching In
 
Joined: Mar 2021
Posts: 20
Likes: 0
Default

Anybody?
Reply
Old Mar 28, 2021 | 07:10 AM
  #3  
Hammer31's Avatar
Thread Starter
Teching In
 
Joined: Mar 2021
Posts: 20
Likes: 0
Default

Come on guys just looking for ideas....I think knock sensor kicked in but that the only thing i can come up with.
Reply
Old Mar 28, 2021 | 07:37 AM
  #4  
smokeshow's Avatar
TECH Senior Member
iTrader: (17)
 
Joined: Feb 2009
Posts: 6,687
Likes: 44
From: Detroit
Default

Post the data.
Reply
Old Mar 28, 2021 | 09:40 AM
  #5  
Hammer31's Avatar
Thread Starter
Teching In
 
Joined: Mar 2021
Posts: 20
Likes: 0
Default

I cant seem to get the info from the tuner...he will only give me the graph and said he has no clue. he did not detect the knock sensor in the run.
Reply
Old Mar 29, 2021 | 11:44 AM
  #6  
minytrker's Avatar
9 Second Club
20 Year Member
Photogenic
iTrader: (13)
 
Joined: Sep 2004
Posts: 1,979
Likes: 273
From: Brenham
Default

1 of 3 things....it pulled timing, closed the throttle blade, or air/fuel changed drastically.
Reply
Old Mar 29, 2021 | 12:49 PM
  #7  
Hammer31's Avatar
Thread Starter
Teching In
 
Joined: Mar 2021
Posts: 20
Likes: 0
Default

Originally Posted by minytrker
1 of 3 things....it pulled timing, closed the throttle blade, or air/fuel changed drastically.
The way it totally crashes, length of the crash is the same all 3 runs...and the time it crashes is totally random all three runs.
just so weird.
Reply
Old Mar 29, 2021 | 12:53 PM
  #8  
Hammer31's Avatar
Thread Starter
Teching In
 
Joined: Mar 2021
Posts: 20
Likes: 0
Default

I have done everything right and this is where i am, tuner i guess is holding on to his trade secrets and wont give me any info. Like who do you go to when the tuner cant help me? Beyond frustrated.
Truck is a dog in a rolling start and then kicks in hard before the shift.
Reply
LS1 Tech Stories

The Best V8 Stories One Small Block at Time

story-0

Amazing '71 Camaro Restomod Is Modern Muscle Car Under the Skin

 Verdad Gallardo
story-1

6 Common C5 Corvette Failures and What's Involved In Repairing Them

 Pouria Savadkouei
story-2

Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph

 Verdad Gallardo
story-3

Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked

 Pouria Savadkouei
story-4

Top 10 Most Powerful Chevy Trucks Ever Made!

 
story-5

Hennessey's New Supercharged Silverado ZR2 Has 700 HP

 Verdad Gallardo
story-6

Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes

 Verdad Gallardo
story-7

Awesome K5 Blazer Restomod Comes With C7 Corvette Power

 Verdad Gallardo
story-8

10 Camaros You Should Never Buy

 
story-9

10 LS Engine Myths That Refuse to Die

 Verdad Gallardo
Old Mar 29, 2021 | 01:04 PM
  #9  
QwkTrip's Avatar
TECH Fanatic
15 Year Member
Photogenic
Photoriffic
Shutterbug
iTrader: (23)
 
Joined: Sep 2010
Posts: 1,324
Likes: 404
From: USA
Default

Where are you located? Maybe somebody can suggest a different tuner in your area.
Reply
Old Mar 29, 2021 | 01:09 PM
  #10  
Hammer31's Avatar
Thread Starter
Teching In
 
Joined: Mar 2021
Posts: 20
Likes: 0
Default

South Jersey...is this normal for a tuner?
Reply
Old Mar 30, 2021 | 11:48 AM
  #11  
Hammer31's Avatar
Thread Starter
Teching In
 
Joined: Mar 2021
Posts: 20
Likes: 0
Default

Originally Posted by smokeshow
Post the data.
Ok here it is...looks to me like Knock sensor kicked in at 1984 RPM's?
Attached Files
File Type: csv
dyno run.csv (1.62 MB, 34 views)
Reply
Old Mar 30, 2021 | 05:31 PM
  #12  
smokeshow's Avatar
TECH Senior Member
iTrader: (17)
 
Joined: Feb 2009
Posts: 6,687
Likes: 44
From: Detroit
Default

Nothing really stands out in that data. Can you feel it or are you just fixating on how it looks on the graph?
Reply
Old Mar 30, 2021 | 05:44 PM
  #13  
Hammer31's Avatar
Thread Starter
Teching In
 
Joined: Mar 2021
Posts: 20
Likes: 0
Default

Does that not show the knock sensor at 1984 RPM to like 2200RPM? Yes i can feel it,
Reply
Old Mar 30, 2021 | 05:55 PM
  #14  
Hammer31's Avatar
Thread Starter
Teching In
 
Joined: Mar 2021
Posts: 20
Likes: 0
Default

Originally Posted by Hammer31
Does that not show the knock sensor at 1984 RPM to like 2200RPM? Yes i can feel it,
ugh wrong column...2700-2819 RPM
Reply
Old Mar 30, 2021 | 07:18 PM
  #15  
Hammer31's Avatar
Thread Starter
Teching In
 
Joined: Mar 2021
Posts: 20
Likes: 0
Default

Ok so the dip on the graph is at 3200 RPM so its not knock sensor...all im seeing is a ramp up 17 to 19 degrees timing at that point and back down to 18 after the dip.
Reply
Old Mar 30, 2021 | 07:56 PM
  #16  
smokeshow's Avatar
TECH Senior Member
iTrader: (17)
 
Joined: Feb 2009
Posts: 6,687
Likes: 44
From: Detroit
Default

Looks like it's just following the spark surface normally. You could probably stand some more spark advance for sure. But nothing really screams 'problem' here. Those dips are all over the place too.
Reply




All times are GMT -5. The time now is 03:10 PM.

story-0
Amazing '71 Camaro Restomod Is Modern Muscle Car Under the Skin

Slideshow: This heavily modified 1971 Camaro mixes classic muscle car styling with a fifth-generation Camaro interior and modern LS3 power.

By Verdad Gallardo | 2026-05-12 18:06:42


VIEW MORE
story-1
6 Common C5 Corvette Failures and What's Involved In Repairing Them

Slideshow: From wobbling harmonic balancers to failed EBCMs, these are the issues that define long-term C5 ownership and what repairs typically involve.

By Pouria Savadkouei | 2026-05-07 18:44:57


VIEW MORE
story-2
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph

Slideshow: A modern Camaro transformed into a retro icon, this limited-run "Bandit" build blends nostalgia with brute force in a way few revivals manage.

By Verdad Gallardo | 2026-04-21 13:57:02


VIEW MORE
story-3
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked

Slideshow: Cadillac didn't just crash the high-performance luxury vehicle party, it showed up loud, supercharged, and occasionally a little unhinged...

By Pouria Savadkouei | 2026-04-16 10:05:15


VIEW MORE
story-4
Top 10 Most Powerful Chevy Trucks Ever Made!

Slideshow: Top ten most powerful Chevy trucks ever made

By | 2026-03-25 09:22:26


VIEW MORE
story-5
Hennessey's New Supercharged Silverado ZR2 Has 700 HP

Slideshow: Hennessey has turned the Silverado ZR2 into a 700-hp off-road monster with supercharged V8 power and a limited production run.

By Verdad Gallardo | 2026-03-24 18:57:52


VIEW MORE
story-6
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes

Slideshow: A one-off sports car that looks like a vintage Italian exotic-but hides a C6 Corvette underneath-just sold for the price of a new mid-engine Corvette.

By Verdad Gallardo | 2026-03-23 18:53:41


VIEW MORE
story-7
Awesome K5 Blazer Restomod Comes With C7 Corvette Power

Slideshow: A heavily reworked 1972 K5 Blazer swaps its off-road roots for a low-slung street-focused build with modern V8 power.

By Verdad Gallardo | 2026-03-09 18:08:45


VIEW MORE
story-8
10 Camaros You Should Never Buy

Slideshow: There are thousands of used Camaros on the market but we think you should avoid these 10

By | 2026-02-17 17:09:30


VIEW MORE
story-9
10 LS Engine Myths That Refuse to Die

Slideshows: Which one of these myths do you believe?

By Verdad Gallardo | 2026-01-28 18:10:11


VIEW MORE