Shifting backfire

[jlagnese@massed.net (John Lagnese)]

That is the symptom, it jumps around while viewed with the timing light.

Rabbit16v wrote:

> Not necessarily, Dan.  If it is jumping around it could just be a rough or
> irratic idle.  I think this is what he is talking about in the first place.
> Shining the t-light on the timing marks and the timing looks to be jumping
> around.  There is a possiblity that the key is broken but it is dependant on
> what he means by "timing jumping around" I guess.
>
> Dave
> ----- Original Message -----
> From: "Dan Bubb" <jdbubb@ix.netcom.com>
> To: "calimus" <calimus@techography.net>
> Cc: "Scirocco-l" <scirocco-l@scirocco.org>; "John Lagnese"
> <jlagnese@massed.net>
> Sent: Monday, February 10, 2003 5:04 AM
> Subject: Re: Shifting backfire
>
> > Just as a quick check shine your timing light on the crankshaft pulley.
> > If it's jumping around then your crank to timing pulley key is shot.
> > That'll make both ignition and cam timing jump around.
> > As far as the exhaust pop, my experience is this is almost always an
> > exhaust leak (yep I read you have new mufflers) that allows air into the
> > exhaust on overrun and lights off any fuel in the pipe causing the pop.
> > Dan
> >
> > calimus wrote:
> > >
> > > I could be wrong, but if your timing is jumping then that very well
> could be
> > > the cause of your backfire problem.  Actually, I would almost bet money
> on
> > > it.  As for why it's jumping, the timing belt would be the first thing I
> > > looked at.  Replace it and if it continues, you might want to look at
> the
> > > tensioner being faulty.
> > >
> > > William
> > > ----- Original Message -----
> > > From: "John Lagnese" <jlagnese@massed.net>
> > > Cc: <a2-16v-list@mail.a2-16v.com>; "The List" <scirocco-l@scirocco.org>
> > > Sent: Monday, February 10, 2003 12:54 AM
> > > Subject: Shifting backfire
> > >
> > > > Hi,
> > > > I'm getting a curious problem in my daily driver. Its a 91 Jetta GL
> 8V.
> > > Its got
> > > > 194K. When I shift above 4k there a small pop, like a backfire? Do I
> have
> > > a
> > > > sticking valve? Its got a new mid and rear muffler, so the exhaust is
> > > tight.
> > > > Also same vehcile, why would the timing mark jump around? Is my timing
> > > belt
> > > > tired?
> > > > Thanks,
> > > > John
> > > >
> > > >
> > > >
> > > >
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