[Diy_efi] Post 4-Wire O2 Sensor Swap Observations...

[David Cooley]

First, lean makes the exhaust "pop" or burble on decel due to extreme
leanness.  it is so lean on decel that you getincomplete/no burn on some
cylinders.  this travels down the exhaust and ignites when it get's hit by a
flame from an exhaust port, or something hot in the exhaust.  I can
demonstrate on my Harley the lean decel pop by leaning the idle screw while
slowing on engine brake to a stop, but if I richen it up even 1/4 turn, it
goes away.
2nd, the Exhaust leak not only lets exhaust out, but in between exhaust
pulses it actually lets air into the exhaust system.  The O2 sensor then
reads lean as there is now more O2 in the exhaust stream reaching it that
there was that left the motor.  My dodge ram has a problem sealing the
drivers side collector to the down pipe, and I can always tell when it has
started leaking because my L.T. fuel trim shows I am very lean, and my
mileage takes a 12-15% nosedive 


  _____  

From: diy_efi-bounces at diy-efi.org [mailto:diy_efi-bounces at diy-efi.org] On
Behalf Of Donovan, Larry
Sent: Friday, April 22, 2005 1:20 PM
To: 'diy_efi at diy-efi.org'
Subject: RE: [Diy_efi] Post 4-Wire O2 Sensor Swap Observations...





-----Original Message----- 
From: David Cooley [mailto:n5xmt at bellsouth.net] 
Sent: Friday, April 22, 2005 12:35 PM 
To: 'Mike Frels'; diy_efi at diy-efi.org 
Subject: RE: [Diy_efi] Post 4-Wire O2 Sensor Swap Observations... 

Popping on decel is from lean, not rich... 
And if you had an exhaust leak before the O2, it may read lean, but mileage
would go down the toilet as it would be richening the mixture up to
compensate.


Neither of these make sense to me. How can popping be from lean and how can
an exhaust leak cause the oxygen sensor to read lean? How can an exhaust
leak change the amount of oxygen remaining in the exhaust. Please explain.

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