A/F ratio....
Thread Starter
Former Vendor
Joined: Jun 2001
Posts: 7,204
Likes: 6
From: St Marys PA
I put my car on an OTC scanner and the meter stayed at lean the whole time at idle. It should be bouncing back and forth, right? How can i adjust the a/f ratio? I am just now getting started in the prom business 
Oh yeah and I pulled a few plugs and they are very white on the ends with a little carbon on the threads. What are your guys opinions?
Oh yeah and I pulled a few plugs and they are very white on the ends with a little carbon on the threads. What are your guys opinions?
Le Mans Master
Joined: Dec 1999
Posts: 8,540
Likes: 1
From: And on the fifth day, subpoenas were served to Obama senior staff
Really don't know how you can read mixture w/o a wide band O2 sensor. Stock O2's can really only read 14.7/1 with any accuracy. BLM's will tell a story of what it takes, as compared to factory pre-sets, to reach 14.7/1, but that's about it. Guessing buy looking at cross counts and looking at O2 readings can be misleading. Spark plug deposits can be revealing, but require some study and experience which I can't help with too much. White usually indicates lean on the electrodes, build up on the threads usually means the plug is too loose or otherwise not sealing correctly.
Good Luck,
Pete
Good Luck,
Pete
Pro
Joined: Jun 2001
Posts: 697
Likes: 0
From: College Station Tx
In addition to what was said above, you can't adjust your part throttle a/f ratio unless you go into an open loop (ignores O2 sensor) program - the stock O2's "adjust" the a/f mixture to achieve 14.7:1. If you go open loop you really need access to a wideband to insure a proper mixture.
You can alter your a/f ratio at wot - my suggestion would be to purchase tunercat for your particular pcm and take it from there (you will need a chip burner/eraser also.)
Team Owner
Joined: Mar 1999
Posts: 22,025
Likes: 192
From: At the beach in little Rhody
I have to admit I am not sure what you are asking. The O2 sensor should be sweeping a sine wave, if that is part of your question. If you are starting in the "PROM" business, I would suggest that you read up on how to proceed with any modifications to the fuel or ignition tables prior to making changes. As you probably know, changes to the lean side can result in a toasted motor if you are not careful.
Thread Starter
Former Vendor
Joined: Jun 2001
Posts: 7,204
Likes: 6
From: St Marys PA
Thanks for the replies. I am going to do quite a bit of studying before doing anything to my prom. I would think that the OTC scanner should have been going back and forth between rich adn lean. I will hook it up to my buddies vette and see if he gets any different readings. Any other suggestions?
Team Owner
Joined: Apr 2001
Posts: 22,267
Likes: 3
From: Dallas TX
Originally Posted by PeteL
Really don't know how you can read mixture w/o a wide band O2 sensor. Stock O2's can really only read 14.7/1 with any accuracy. BLM's will tell a story of what it takes, as compared to factory pre-sets, to reach 14.7/1, but that's about it. Guessing buy looking at cross counts and looking at O2 readings can be misleading. Spark plug deposits can be revealing, but require some study and experience which I can't help with too much. White usually indicates lean on the electrodes, build up on the threads usually means the plug is too loose or otherwise not sealing correctly.
Good Luck,
Pete
[/color]
Good Luck,
Pete
[/color]
My measurements are straight off of a dyno with AFR measurements.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Top 10 Corvette Engines RANKED by Peak Torque (70+ Years of Muscle!)
Joe Kucinski
Corvette ZR1X Will Be Pacing the Indy 500, And Could Probably Race, Too!
Verdad Gallardo