LT1-LT4 Modifications 1993-97 Gen II Small Block V8

Running rich, no codes.

Thread Tools
 
Search this Thread
 
Old Aug 5, 2011 | 06:53 PM
  #1  
Z28Roxy's Avatar
Thread Starter
TECH Fanatic
15 Year Member
iTrader: (4)
 
Joined: Mar 2007
Posts: 1,011
Likes: 27
From: Waukesha, WI
Default Running rich, no codes.

Here is a datalog, can anyone help me figure this out - why I'm getting 14 mpg on the HWY?

http://www.mediafire.com/?3e4tp5gt7tk0hml
Reply
Old Aug 5, 2011 | 08:36 PM
  #2  
rich5368's Avatar
TECH Regular
iTrader: (2)
 
Joined: Apr 2010
Posts: 442
Likes: 0
From: Cheyenne, WY
Default

I don't know for certain that you're going to necessarily drop codes if you're rich. I was running rich after my header install and it turned out being faulty O2s that I apparently jacked up when I reinstalled them.
Reply
Old Aug 5, 2011 | 09:06 PM
  #3  
ws6t3rror's Avatar
Launching!
15 Year Member
iTrader: (3)
 
Joined: Apr 2007
Posts: 209
Likes: 0
Default

Vacuum looks not so great for the combo in your sig and the speed/load you were running. Timing is low for the cruising speed and load at around 32 deg should be more like 37-40 if not a bit more depending on the combo. Try and keep it under 1800 rpm... go faster and get into 6th, less vacuum, less engine speed, more ground speed.

Lots of cold starts will absolutely destroy your econ.

I don't really see anything crazy just the small things I mentioned.

Airflow isn't high enough to make it jump out at least to me, then again 10% is only 2.5g/sec.

Also you have what seems like some very large injectors. It takes time to open and close them, the big injectors make the control crappy. If you can only trim in 0.1ms increments, and you only have 2.0ms to fire the injector and 1ms of that is opening and closing what are you left with for fuel control? That might account for a little bit of your issue.
Reply
Old Aug 6, 2011 | 08:18 AM
  #4  
Z28Roxy's Avatar
Thread Starter
TECH Fanatic
15 Year Member
iTrader: (4)
 
Joined: Mar 2007
Posts: 1,011
Likes: 27
From: Waukesha, WI
Default

Originally Posted by ws6t3rror
Vacuum looks not so great for the combo in your sig and the speed/load you were running. Timing is low for the cruising speed and load at around 32 deg should be more like 37-40 if not a bit more depending on the combo. Try and keep it under 1800 rpm... go faster and get into 6th, less vacuum, less engine speed, more ground speed.

Lots of cold starts will absolutely destroy your econ.

I don't really see anything crazy just the small things I mentioned.

Airflow isn't high enough to make it jump out at least to me, then again 10% is only 2.5g/sec.

Also you have what seems like some very large injectors. It takes time to open and close them, the big injectors make the control crappy. If you can only trim in 0.1ms increments, and you only have 2.0ms to fire the injector and 1ms of that is opening and closing what are you left with for fuel control? That might account for a little bit of your issue.
What about the O2 mvs, how they vary so much?
Reply
Old Aug 6, 2011 | 09:34 AM
  #5  
mguidry629's Avatar
TECH Regular
iTrader: (6)
 
Joined: Aug 2010
Posts: 401
Likes: 0
From: Baton Rouge, LA
Default

Am I the only one that sees the "data ok" box flash red every so often? Also, does anyone else see a 5 second gap between rec# 242-243? Just wondering if it's just my computer or the actual datalog because all my logs do that and with the sound up it dings and gets very aggrevating.

But to the OP, I only have experience with datalogging my car, so I'm no expert....but my O2 mvs jump around like that too. I'm pretty sure that's normal.

Do you have a wideband O2? How do you know it's running rich? What kind of O2's and how old are they?
Reply
Old Aug 6, 2011 | 11:32 AM
  #6  
ws6t3rror's Avatar
Launching!
15 Year Member
iTrader: (3)
 
Joined: Apr 2007
Posts: 209
Likes: 0
Default

The o2 mv are SUPPOSED to do that. There is no mystery as to why, and I will explain. The narrow band can't tell you anything besides which side of stoich it is on (no matter what the stoich is for your pump fuel this week). So what your pcm does is based on a set point in mv for o2 switching it adds and pulls fuel to try and cross that switch point. Its really a simple and somewhat dumb algorithm. If its on the rich side the short term trims pull fuel and if its on the lean side they add fuel until they cross the threshold. What you get is an average a/f ratio of stoich for your fuel. The only calibration work on the oem side is to set the gains for the short term and long term trims achieve some stability. Pretty easy task on a dyno with a dev ecm.

If you look at the response of a narrow band to air fuel ratio it should be obvious why it works this way. Its also dirt cheap and effective.

The data box thing is probably because of her data cable being loose a usb/rs232 adapter or some other wiring issue.
Reply




All times are GMT -5. The time now is 06:16 PM.

story-0
6 Gifts Neither Your Dad Nor Grad Will Shove Into the 'Trinket Drawer'

Don't get dad new socks or a grill brush this year.

By Brett Foote | 2026-06-09 14:55:56


VIEW MORE
story-1
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-2
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-3
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-4
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-5
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-6
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-7
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-8
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-9
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