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

Is This Possible???

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Old Sep 10, 2002 | 10:09 AM
  #1  
csabatka1's Avatar
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From: Maryville, MO/Seward, NE
Question Is This Possible???

My passenger side was running extremely rich due to a header leak not too long ago. I fixed the header leak, and replaced the plugs on that side due to the rich condition fouling the plugs, causing a weak spark.

My problem now is that from time to time the passenger side is running rich for some odd reason. It'll be fine for a couple minutes (almost always fine in WOT), but from time to time it'll think it's running lean on the passenger side when in fact its not running lean.

Would it be possible to tune/rig the PCM into only reading one (driver's side) o2 sensor?

**Both o2 sensors are brand new, fixed header leak, might leak from time to time causing this problem

------------------
-Chad

1994 Firebird Formula 383 Mod List

12.34 @ 114 mph 1.72 60' on stock bottom end

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Old Sep 10, 2002 | 12:49 PM
  #2  
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I believe if it was running lean for a while before you fixed your header leak it may have upset the BLM's and it may still be learning the new A/F ratio.

Although, I am not completly sure if the BLM's are different for each side. Someone else might be able to be more specific.

Try pulling the PCM fuse to reset your BLM table and then the PCM can relearn it. Don't worry you don't lose you programming just the BLM table.

CanadianZ
Old Sep 10, 2002 | 12:53 PM
  #3  
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From: Maryville, MO/Seward, NE
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Thanks for that idea, I'll give that a try later and see if that helps out any.

I don't know if the PCM learns the A/F to each side, but my entire passenger side's plugs were pretty bad (only 250 miles on the plugs) while my driver's side was perfect with a greyish/tan spot on the plug. so that was giving me reason to suspect that the PCM learns each side independently.

------------------
-Chad

1994 Firebird Formula 383 Mod List

12.34 @ 114 mph 1.72 60' on stock bottom end

Project 383 Purchasing/Removal/Rebuilding/Installation Webpage

Founder of Nebraska GM Modern Muscle
Old Sep 10, 2002 | 12:55 PM
  #4  
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<font face="Verdana, Arial" size="2">My problem now is that from time to time the passenger side is running rich for some odd reason. It'll be fine for a couple minutes (almost always fine in WOT), but from time to time it'll think it's running lean on the passenger side when in fact its not running lean. </font>
Not sure I understand what you are trying to say here... first you say the passenger side is running rich from time to time, then you think its running lean????? Do you have any data to support any of this? BLM's? Wideband O2 readings????

<font face="Verdana, Arial" size="2">
Would it be possible to tune/rig the PCM into only reading one (driver's side) o2 sensor?
</font>
It would be suicidal. If you only read the driver's side O2 sensor, a fault in the passenger side would go undetected. Each bank needs the full feedback control, since it is seperate from the other bank. e.g. if you were feeding both banks the drivers side signal, a rich condition in the drivers bank would cause both banks to lean out.

Find the problem... if you can find data to support the feelings that the problem even exists. Don't apply bandaids.



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Fred
94 Formula A3+1: 381/TH400+OD/N2O

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