Shifting backfire

[jdbubb@ix.netcom.com (Dan Bubb)]

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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