[DML] Re: My first tune up: Making progress, not quite there yet

["David Teitelbaum" <jtrealty@xxxxxxxxxxxxx>]

Well, that was clever! The noise is normal. On some cars it is more
pronounced than others and under certain driving conditions it can be
more or less. What is the variable here is the decel valves in the
throttle plates. Make sure they are not stuck and they move easily on
the springs. Much more important on a 5-speed than an automatic. What
is happenning is when you slam the throttle valves shut the mixture
goes rich for an instant until the mixture unit can catch up. During
that instant a slug of over-rich air/fuel goes through the motor and
some of it burns in the exhaust. Most noticeable when you are driving
down a hill and you lift your foot off the gas quickly. Exhaust leaks
can also make the noise worse by letting air into the exhaust to help
the burn and then letting the noise out.
David Teitelbaum
vin 10757



--- In dmcnews@xxxxxxxxxxxxxxx, Ryan Wright <ryanpwright@...> wrote:
>
> Hi David,
> 
> On 2/6/06, David Teitelbaum <jtrealty@...> wrote:
> > Hard to tell what you noise is this far away!
> 
> How about if I bring the noise to you?? :)
> http://www.ryanwright.com/tmp/dglug.mp3
> 
> Notes:
> 
> 1. It doesn't happen when the car is cold (REALLY cold; within 30-60
> seconds of startup I'm OK, after that the noise shows up).
> 
> 2. It only happens on deceleration.
> 
> 3. It's much more pronounced when the idle switch is engaged. If I
> decelerate without hitting the idle switch, it's virtually
> non-existant.
> 
> 4. The noise is worse now that I've got the Lambda system working
> correctly. Go figure?! :)
> 
> 5. If I dial the mixture rich (way rich, at least 1/2+ turn beyond
> where the Lambda system gives up trying to regulate things), the n







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