[Gmecm] Help with unusual BLM's

[Randy & Gene]

     Hi Andrew, today I solved a 3 year mystery as to why my 1993 Pontiac
Sunbird with a 3.1 V6 did exactly what your engine is doing. I had taken it
to a dealer and Mr. Goodwrench charged me close to $1300 Cdn and couldn't
fix the problem in 13 hours. I took it to another fellow who had worked for
GM and he changed the upper and lower manifold gaskets citing there was a
vacuum leak..$500...and another emissions shop charged me close to $200 for
telling me it had a vacuum leak near the back of the engine because when he
sprayed a liquid in that area the engine sped up a bit......this car has a
full body kit installed otherwise I would have towed it to the wrecking
yard...anyway...I bought a 1992 Sunbird with the same engine for
$350....bought a manual and laptop from E Bay and proceeded to swap parts
out...O2,EGR,TPS,MAP,ECU and even checked every mile of cable harness  for
resistance...everything including injectors were swapped, throttle
body.........nothing helped...then I decided to start over with basics....a
simple compression test was first.....pulled all of the spark plug boots
first then took out the 3 front plugs and number one from the back....number
3 was missing....or at least half of it was...part stuck in the boot and the
other in the head......compression was good on all and when I supplied a
plug from my parts car the 3.1 lit up like it was new..........you can't
imagine my joy........the only code I ever got was a 45....rich O2...it had
been replaced...a broken plug........make sure your basic stuff is in order
first and good luck.....Gene

----- Original Message ----- 
From: <ahuxtable at sola.com.au>
To: <gmecm at diy-efi.org>
Sent: Sunday, March 26, 2006 8:04 PM
Subject: [Gmecm] Help with unusual BLM's


Hi all.  I've been trying to work out why for some reason my car has
been running rich.  I just always assumed that it was the O2 sensor
playing up - Until yesterday that is...

I logged some data and the highest BLM I saw was 120.  Most being around
115 so my engine is running fairly rich. So, the computer thinks that
it's running rich and it actually is = not O2 sensor.  Next I thought it
might be the CTS or MAT sensors but logging them, it's all normal.  CTS
reports running temp of ~85DegC (184DegF) and MAT is reading as expected
too.

What else could be forcing the engine to run rich?

Thanks
Andrew
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