Computer Diagnostics and Tuning Technical discussion on diagnostics and programming of the F-body computers

OBDII leaning out closed loop

Old Jul 25, 2005 | 02:31 PM
  #1  
Red on Red WS6's Avatar
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OBDII leaning out closed loop

I bought tunercat a couple of weeks ago and so far I have just messed around with the transmission tables. I use Autotap for my scan tool and I am getting -11% LTFT bank 1 and -9 to -10% on bank 2 this only happens from idle to around 3000 rpm then zeros out. If I am correct the negative value indicates a running rich condition. So my question is what would be the most effictive table to start adjusting? I was going to use the MAF table but I have a good WOT open loop tune and if I change the MAF tables the AF ratio at WOT would change right? Also does anyone have any cal. files they would like to share stock or modded it does not matter I just want to learn and compare as many as I can.

Thanks in Advance.
Old Jul 26, 2005 | 10:07 AM
  #2  
Chris 96 WS6's Avatar
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Re: OBDII leaning out closed loop

Scan the car at idle to see what grams/sec the MAF reads at idle. Then go into the maf table and subtract maybe 3% from the values in just the cells around that g/s airflow value.

So if the car sees 12 g/s at idle, alter the MAF table cells from, say 9 g/s all the way to 15 g/s. That's the only way I know of to custom tailor the tune for specific lean/rich spots.

If it was rich all the way through you would want to tune with injector constant values, but I guess its the same end result to alter the MAF table.
Old Jul 28, 2005 | 12:19 AM
  #3  
Red on Red WS6's Avatar
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Re: OBDII leaning out closed loop

I pulled 3% out and it worked pretty good I am now down to -5 % -6% so it is getting much better. I will try another 2 or 3% and see if that does it.
I have a question about shifting, my 2-3 shift will not shift when I have the car in 3 position. When I have it in D it shifts fine. Does this sound like somthing I can fix with the computer or is it just my tranny going out?

Also I noticed somthing odd the past couple of day's every now and then when I am sitting at a light my speedometer just jumps up to 75MPH then back to zero. Anyone ever had this happen?
Old Jul 28, 2005 | 07:57 AM
  #4  
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Re: OBDII leaning out closed loop

The 2-3 shift issue might be the shift settings in the PCM. Check the shift MPH for manual mode and compare them to normal mode and see if there's a difference for the 2-3 shift.
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