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05-18-2006, 07:36 PM
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#1
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AF Newbie
Join Date: Aug 2005
Location: Granville, Massachusetts
Posts: 22
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Bank one lean @ 79 MPH
Got the "light" today and checked it out when I got home. Code triggering the light (drivetrain) was "Bank One Lean". The snapshot said it happened @ 79 MPH. Never exceeded 55 MPH in the last week! Wha? ('98 4WD, standard)
Tom
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05-18-2006, 08:54 PM
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#2
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AF -Advisor
Join Date: Sep 2003
Location: Sudbury
Posts: 13,562
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Re: Bank one lean @ 79 MPH
What year?
__________________
1995 Factory Blazer Service Manual for sale, PM if interested.
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05-18-2006, 09:05 PM
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#3
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AF Newbie
Join Date: Aug 2005
Location: Granville, Massachusetts
Posts: 22
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Re: Bank one lean @ 79 MPH
LT,
'98, 4WD, standard. It's in the post. Good to see you back around.
Tom
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05-18-2006, 10:14 PM
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#4
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AF -Advisor
Join Date: Sep 2003
Location: Sudbury
Posts: 13,562
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Re: Bank one lean @ 79 MPH
Lean sensor signals are usually linked to a dirty MAF sensor.
__________________
1995 Factory Blazer Service Manual for sale, PM if interested.
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05-19-2006, 12:39 AM
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#5
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AF Fanatic
Join Date: Oct 2004
Location: Muskegon, Michigan
Posts: 2,835
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Re: Bank one lean @ 79 MPH
depending on mileage it could also be a sticky o2 ... was the only code a lean or was there more? what secer detected the issue and set the code?
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05-19-2006, 01:01 AM
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#6
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AF -Advisor
Join Date: Sep 2003
Location: Sudbury
Posts: 13,562
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Re: Bank one lean @ 79 MPH
Quote:
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Originally Posted by dmbrisket 51
depending on mileage it could also be a sticky o2 ... was the only code a lean or was there more? what secer detected the issue and set the code?
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You have to watch it there, it is sensing something which doesn't mean it is defective.
I worked on a 1997 that was having lean problems and codes and it came back to a faulty dirty MAF screwing up all the fuel trim values.
Cleaned the MAF and all went back to normal. Had one guy that had to change the MAF completely in order to get the fuel system right again.
__________________
1995 Factory Blazer Service Manual for sale, PM if interested.
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05-19-2006, 01:30 AM
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#7
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AF Fanatic
Join Date: Oct 2004
Location: Muskegon, Michigan
Posts: 2,835
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Re: Bank one lean @ 79 MPH
but its only detecting it on one bank and not both, thats the only reason for my though of a bad o2, could also be a vaccume leak (severe)
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05-20-2006, 06:45 PM
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#8
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AF Newbie
Join Date: Aug 2005
Location: Granville, Massachusetts
Posts: 22
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Re: Bank one lean @ 79 MPH
I dumped the code, but remember that an O2 sensor was out of range. I watched it run and noticed that one was "spikeing" (but didn't register as a code or "pending code). I should have saved a graph to post . Then again, 170k miles!
I just thought that the 79 MPH was wierd.
Tom
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05-20-2006, 09:56 PM
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#9
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AF Fanatic
Join Date: Oct 2004
Location: Muskegon, Michigan
Posts: 2,835
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Re: Bank one lean @ 79 MPH
they should run between low 100 ish to 200 tops, and 7 or 800 on the top end when under a load
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10-30-2006, 06:11 PM
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#10
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AF Newbie
Join Date: Aug 2005
Location: Granville, Massachusetts
Posts: 22
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Re: Bank one lean @ 79 MPH - update
I know it's a late reply, sorry I had some problems. I took your advice and cleaned up the MAF sensor this past weekend. I also cleaned up and tightened the duct connections downstream of the sensor. No more lean burn! Passed inspection today - thanks for the tips.
Tom
Now it sounds like it's bearing/hub time again!
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10-30-2006, 06:57 PM
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#11
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AF -Advisor
Join Date: Sep 2003
Location: Sudbury
Posts: 13,562
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Re: Bank one lean @ 79 MPH - update
Quote:
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Originally Posted by firepaw
I know it's a late reply, sorry I had some problems. I took your advice and cleaned up the MAF sensor this past weekend. I also cleaned up and tightened the duct connections downstream of the sensor. No more lean burn! Passed inspection today - thanks for the tips.
Tom
Now it sounds like it's bearing/hub time again!
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Glad to have helped you.
And thanks for letting us know how things went. 
__________________
1995 Factory Blazer Service Manual for sale, PM if interested.
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