PCM Diagnostics & Tuning HP Tuners | Holley | Diablo

ever seen this? timing observation / question

Thread Tools
 
Search this Thread
 
Old Oct 5, 2005 | 10:47 AM
  #1  
Blackbird's Avatar
Thread Starter
TECH Addict
 
Joined: Nov 2001
Posts: 2,659
Likes: 1
From: Bellevue, Wa
Default ever seen this? timing observation / question

looking at my logs today, looks like when I get off the gas my advance will dip all the way down as low at 3 degrees and then work it's way back up into the high 30's.

any ideas what would cause the car to do this? or is it normal and I have just never noticed.

I am scouring the logs better these days trying to solve my darn pig rich during decel issue.
Reply
Old Oct 5, 2005 | 10:53 AM
  #2  
87GMC's Avatar
Launching!
 
Joined: Apr 2004
Posts: 237
Likes: 0
From: Odessa, Texas
Default

are you m6 or auto?
Reply
Old Oct 5, 2005 | 11:01 AM
  #3  
HumpinSS's Avatar
FormerVendor
iTrader: (1)
 
Joined: Feb 2002
Posts: 3,059
Likes: 0
From: Waldorf, MD
Default

DFCO ro Deceleration Fuel Cutoff what are your injectors doing at this time
Reply
Old Oct 5, 2005 | 11:24 AM
  #4  
Blackbird's Avatar
Thread Starter
TECH Addict
 
Joined: Nov 2001
Posts: 2,659
Likes: 1
From: Bellevue, Wa
Default

m6.

o2's do drop along with the timing drop.

it only does it for a few frames but I just found it odd. could it perhaps be dfco kicking in for a brief second and then exiting? I ask because I have a problem with the car going pig rich during decel and will not recover until I hit the gas. My current assumption is that DFCO is not kicking in as it should.
Reply
Old Oct 5, 2005 | 01:42 PM
  #5  
patSS/00's Avatar
TECH Fanatic
20 Year Member
Photogenic
Photoriffic
Liked
iTrader: (6)
 
Joined: Nov 2001
Posts: 1,010
Likes: 17
From: AZ
Default

I have also found that it goes rich (maybe down to 12+) on decel, but if it stays in decel long enough it goes lean. I mean pretty long, like 8-10 sec. I posted about this awhile back, someone said it was normal.
Reply
Old Oct 5, 2005 | 03:29 PM
  #6  
Ragtop 99's Avatar
TECH Senior Member
iTrader: (7)
 
Joined: Nov 2001
Posts: 9,491
Likes: 1
From: Bethesda, MD
Default

Originally Posted by patSS/00
I have also found that it goes rich (maybe down to 12+) on decel, but if it stays in decel long enough it goes lean. I mean pretty long, like 8-10 sec. I posted about this awhile back, someone said it was normal.
I'm experiencing this too. Plays havoc on the trims, because my low MAP VE is reduce to counteract it going rich on initial decel and then eventually my STRIMs start going over 10%+ if I don't get back on the thottle.
Reply
Old Oct 6, 2005 | 12:22 AM
  #7  
Blackbird's Avatar
Thread Starter
TECH Addict
 
Joined: Nov 2001
Posts: 2,659
Likes: 1
From: Bellevue, Wa
Default

looked at more logs from the ride home.

I guess dfco is kicking in now!

let off the gas car goes super rich, then goes ultra lean, guage read 20:1 you can see on the logs the 02's read zero, advance is zero and A/F just climbs and climbs off the charts until I touch the throttle. I am going to put my VE back to close to stock values down low to see how that effects things. This off throttle very light throttle, low load tuning is kicking my ***. cruise at wot are just fine but this....... arghhhh
Reply




All times are GMT -5. The time now is 06:31 PM.

story-0
Topdon ONE vs. Artidiag 800 BT2: Which is the Diagnostic Tablet For You?

Slideshow: We take a close look at the ONE and Artidiag 800BT2 diagnostic tools from Topdon and the reasons to buy one over the other.

By Pouria Savadkouei | 2026-05-28 11:05:11


VIEW MORE
story-1
Gas Monkey Built a 6-Wheel Ferrari Testarossa With a Corvette LT4 Engine

Slideshow: The controversial Ferrari F6 swaps its original flat-12 for a Corvette Z06-derived LT4 V8 and sends power to four rear wheels through a custom-built drivetrain.

By Verdad Gallardo | 2026-05-26 18:23:54


VIEW MORE
story-2
7 Most Reliable High-Performance Engines GM Has Ever Built

Slideshow:These GM engines didn't just make huge power, they survived abuse, boost, track days, and six-digit mileage with a reputation for refusing to quit.

By Verdad Gallardo | 2026-05-21 16:45:27


VIEW MORE
story-3
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-4
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-5
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-6
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-7
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-8
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-9
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