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Bad MPG - WBO2 vs ECU

Dan D

Well-known member
Joined
Feb 27, 2001
Messages
1,171
Location
Brownsburg, IN
I need some help sorting through a closed-loop fuel dilemma. For starters I’m using an Ostrich, Tunerpro+Hexeditor, Pocketlogger, and an LC-1 WBO2 (logged on egr input). Running FIC 1050cc injectors properly compensated for in the code.

My fuel mileage suck. I’m getting 14mpg and I’ve been breaking in a clutch so I know I’m not standing on the gas.

My fuel trims are: H = 102, M = 115, L = 125
At idle and steady cruise, my wideband reads ~14.2

I think I have to trust what the wideband says because it’s the most accurate feedback device I have at my disposal. It says I’m rich and my MPG support that. However, the fuel trims say the ecu thinks I’m lean and the ecu keeps adding fuel to compensate. My injector size settings and fuel pressure seem to be good based on my high trim being really close to 100.

How do I close the gap between the reality (rich on WBO2) and what the ecu thinks (lean in fuel trims)? Is this a deadtime issue, is my narrow band O2 failing - It cycles at normal speeds and doesn’t seem to be on the fritz, but it is 50k miles old.

Advice and opinions welcome.
 

I had some similar issues with my setup fuel trims were pig rich at 82% except for my mid trim which never moves while my wideband told a different story my plugs were showing that I was lean also and she was puffing black smoke under boost? Couple of things check for boost leaks number 1 my wg to mbc silicone hose was leaking and then finally ripped fixing that cured half my issues. Secondly you should only use the wide band for wot tuning the computer should adjust for anything else at idle or partial throttle. The wide band reading can very too much based on its from location where its installed or a bad O2/wb sensor etc. Third check to make sure your battery as well as your fuel pump are in good working order my car would run perfect at partial throttle cruising etc at full boost she would go lean no matter how much fuel i added turns out after looking at my logs my battery voltage was going way down below 12 volts under boost and I think my fuel pump may have a dirty sock filter both will be addressed this week. My fuel trims are also now within spec all near 100% and it doesnt smoke under boost anymore I just need to deal with the battery voltage and fuel pump now good luck....
 

jepherz

Staff member
Joined
Aug 8, 2004
Messages
7,877
Location
KC, Missouri
This is going to sound strange, but my car is running the first gen. Ostrich and an LC-1. I know it's not exactly your situation, but for a long time, my car would run super rich, like 9:1 and had NO power what-so-ever. I couldn't even back up my driveway. I found it to be a flashing issue with the Ostrich, and a few bits were getting corrupt in some way.

Anyways, which version of ostrich are you running? Do you have any method to burn an actual chip with the same image that's on your Ostrich?
 
Last edited:

Dan D

Well-known member
Joined
Feb 27, 2001
Messages
1,171
Location
Brownsburg, IN
I'll have to look and see what version it is. It's pretty new - bought it last summer. What gets me is that the open loop stuff works great. Before the clutch/tranny fiasco,wide open it ran like a raped ape. I was always on it when driving so I dismissed the poor mpgs. Not until recently while I've been easy on the gas breaking in the new clutch did it hit me that there might be a problem.

I can try a chip. I have a burner. Well see what happens.
 
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