Why are my A/F ratios not consistent?

Reply Subscribe

Thread Tools

Search this Thread

Nov 30, 2003 | 08:12 PM

StupidFast

Thread Starter

TECH Enthusiast

Joined: Dec 2002

Posts: 698

Likes: 0

From: Fort Worth

Why are my A/F ratios not consistent?

I am tuning my truck NA. I have to place my truck into open loop to program my A/F ratio. I got it to 12.9 and was happy. However, driving back to my house I decked it and it read 11.7. I floored it again and found that I got a 12.3. Once again, it read a 12.8. Any ideas? Thanks alot.

Nov 30, 2003 | 09:21 PM

red ws6 99

TECH Fanatic

Joined: Nov 2001

Posts: 1,190

Likes: 0

From: Las Cruces, NM

First are you using a in-car wideband o2 setup, if not don't trust the stock o2s? If you are using a wideband have you turned off COT Catylst (spelling) over temperature. If the computer thinks you might be getting the Cats hot it will dump in more fuel which usually gives AFR in the 11.5 range. Turn that off and then see if it happens.

Gary

Nov 30, 2003 | 09:25 PM

WS6FirebirdTA00

TECH Senior Member

iTrader: (33)

Joined: Mar 2003

Posts: 8,319

Likes: 1

From: North Carolina

i get a more consistent reading than that with my stock o2's in my car

Nov 30, 2003 | 10:17 PM

StupidFast

Thread Starter

TECH Enthusiast

Joined: Dec 2002

Posts: 698

Likes: 0

From: Fort Worth

The COT is turned off. I have a FJO wideband installed the the collector on my driver's side header. I will try to drive it more and see what happens. Weird.

Nov 30, 2003 | 10:48 PM

Slowhawk

LS1Tech Sponsor

iTrader: (12)

Joined: Nov 2001

Posts: 14,865

Likes: 6

From: Bridgewater,Ma

Are you reading intake air temp too?That can make a difference in a Supercharged application.

Nov 30, 2003 | 11:25 PM

CAT3

Restricted User

iTrader: (9)

Joined: Sep 2002

Posts: 7,603

Likes: 0

From: Sierra Vista, AZ

I had similar readings using a different wideband because I took one of the O2s out to place the wideband in, messes up that reading alot.

Nov 30, 2003 | 11:50 PM

Texas Terminator

11 Second Club

Joined: Jul 2002

Posts: 1,426

Likes: 0

From: Beaver Falls, PA

hey man! i think slowhawk may have your solution. at least some kind of temperature issue. not much else that could make your numbers swing that much without setting a code of some sort i would think. do you have it logged? i know you don't have the FMU installed, are you having fuel pressure issues at all? is your IFR table scaled or the same across the board? on that note what are your MAP numbers?

BTW, i got my injectors, headers, and new exhaust in. oh ****! and i still don't have quite 7psi! give me a call this week sometime.