False Narrow Band O2 Data At Idle
False Narrow Band O2 Data At Idle Okay guys.. Another minor issue I'm experiencing. I tuned the shop truck we use to chase parts using a Wide Band and Hp Tuners. I did the VE table, and the MAF table separately. After multiple tuning sessions I got it +/-3% across the board. However, once I put the factory narrow bands back on line everything was good driving wise except when I data log it shows that my idle cell (800 RPM at 45 KPA) is lean by about 9%.. This is the ONLY cell out of the entire table that is showing it is lean..... So.. I went in and upped the VE table corresponding cell by 9% just to jump right down on top of the # with the intent that I would most likely be adjusting it again anyway. Cleared the LT fuel trims and went and drove it.. Again, all cells within 3% across the board except the idle cell. Idle cell still showing 9% correction (lean).
I suspect since the truck starts, idles, and runs perfectly before it goes into closed loop that the fueling must be right... but the factory narrow bands disagree and they want to keep adding fuel at idle. Maybe it's because the factory narrow bands don't work well at such low flow.. Maybe it's because I'm using factory cast manifolds but then aftermarket exhaust from the manifold back and the O2 location is different from factory and not seeing enough heat, or exhaust gas flow, at idle.
I'm interested in hearing what you guys think. Yes, I can just leave it alone as the truck has no running issues.. It's only a problem because I know it exists. I only began logging it because we are finally seeing some cooler weather and I needed to do a Idle Config BRAF to populate those lower temperature fields that I could not get during the summer when I was tuning the vehicle. It's cooler in the mornings now.
I suspect since the truck starts, idles, and runs perfectly before it goes into closed loop that the fueling must be right... but the factory narrow bands disagree and they want to keep adding fuel at idle. Maybe it's because the factory narrow bands don't work well at such low flow.. Maybe it's because I'm using factory cast manifolds but then aftermarket exhaust from the manifold back and the O2 location is different from factory and not seeing enough heat, or exhaust gas flow, at idle.
I'm interested in hearing what you guys think. Yes, I can just leave it alone as the truck has no running issues.. It's only a problem because I know it exists. I only began logging it because we are finally seeing some cooler weather and I needed to do a Idle Config BRAF to populate those lower temperature fields that I could not get during the summer when I was tuning the vehicle. It's cooler in the mornings now.
Last edited by Kawabuggy; Oct 27, 2021 at 10:07 AM.
Idle is steady state and it’s using the MAF. So try making the change to the MAF table.
You might also use the VCM control to slowly reduce the idle speed so you catch the freq cells below idle.
You might also use the VCM control to slowly reduce the idle speed so you catch the freq cells below idle.
