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smells rich (was: changed exhaust,...)

To: "Cohen, David M" <d.cohen@hp.com>
Subject: smells rich (was: changed exhaust,...)
From: "John F Sandhoff" <sandhoff@csus.edu>
Date: Tue, 29 Jul 2003 17:16:11 -0700
Drifting off-topic from the original, but hopefully worth something to
someone:

> I have also tried adjusting the air/fuel mixture several times.  The
> car smells like it is running very rich...

Which means that the car is probably running lean.

When you have a lean-burn condition, your unburned hydrocarbons
(HC) climb. This causes the 'unburned gas' smell that you detect. If
everything else is OK, it's likely that you've developed a vacuum
leak that's leaning out the mixture.

In this specific case, a larger, free flowing exhaust improves flow and
is probably flowing more air thru the system. More air = leaner mix.
Also, backfiring on decel is often found to be an intake manifold
leak (i.e. lean mixture at high vacuum).

You probably need to richen things up a bit.

-- John
     John F Sandhoff   sandhoff@csus.edu   Sacramento, CA

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