lean or rich?? what do I Iook for in A-tap
Thread Starter
Launching!
Joined: Mar 2002
Posts: 201
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From: PA
lean or rich?? what do I Iook for in A-tap I have A-tap, and I need help as to what do I look for. Do I need to look at o2's or Ltrims, and what values represent each(rich/lean)?
for example my Ltrims are avg 20% at WOT A rich or lean value? O2's read .888 on avg at WOT
for example my Ltrims are avg 20% at WOT A rich or lean value? O2's read .888 on avg at WOT
FormerVendor
Joined: Apr 2002
Posts: 278
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From: Yorba Linda, CA
Re: lean or rich?? what do I Iook for in A-tap I suggest logging the following:
Engine Speed
Fuel Trim Cell
Throttle Position Angle
LTFT B1
LTFT B2
STFT B1
STFT B2
O2 B1S1
O2 B2S2
Ignition Timing Advance
Knock Retard
Drive the car as you normally would. You'll also want to get some wide open throttle (WOT) blasts. I find that these are easiest on a freeway onramp.
After logging the data, open the log file for playback and export it to comma delimited format. This will open with Microsoft Excel. I suggest sorting the data by fuel trim cell. I group them by the following criteria:
Cells 0-5 and 21 (no load cells)
Cells 6-14 (part throttle)
Cells 17-20 (idle)
Cells 15 and 22 (WOT)
For no load, part throttle, and idle cells I average the STFT's and LTFT's for each group. Anything negative is rich and anything positive is lean.
For WOT I look at cells 15 and 22 with greater than 96% TPS angle. Average the O2 readings. You want to be in the .890 - .910 range. Anything below that is lean and anything above that is rich. I also look for knock retard above 3 degrees at WOT.
I hope this helps.
<small>[ August 14, 2002, 05:10 PM: Message edited by: SSMAN66 ]</small>
Engine Speed
Fuel Trim Cell
Throttle Position Angle
LTFT B1
LTFT B2
STFT B1
STFT B2
O2 B1S1
O2 B2S2
Ignition Timing Advance
Knock Retard
Drive the car as you normally would. You'll also want to get some wide open throttle (WOT) blasts. I find that these are easiest on a freeway onramp.
After logging the data, open the log file for playback and export it to comma delimited format. This will open with Microsoft Excel. I suggest sorting the data by fuel trim cell. I group them by the following criteria:
Cells 0-5 and 21 (no load cells)
Cells 6-14 (part throttle)
Cells 17-20 (idle)
Cells 15 and 22 (WOT)
For no load, part throttle, and idle cells I average the STFT's and LTFT's for each group. Anything negative is rich and anything positive is lean.
For WOT I look at cells 15 and 22 with greater than 96% TPS angle. Average the O2 readings. You want to be in the .890 - .910 range. Anything below that is lean and anything above that is rich. I also look for knock retard above 3 degrees at WOT.
I hope this helps.
<small>[ August 14, 2002, 05:10 PM: Message edited by: SSMAN66 ]</small>
TECH Addict
Joined: Nov 2001
Posts: 2,207
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From: College Station, Tx
Re: lean or rich?? what do I Iook for in A-tap I would suggest that using 0.850 to 0.950 as a bound for stock o2's is a better idea - and that you should use them as a last resort (e.g. if you get knock retard at 0.900 with normal timing I would definitely still richen it up, etc.).
Chris
Chris
