[s-cars] Cutting out at speed

[Ben Swann]

Mike,

1. Fuel pump cut is nearly  instantaneous.
 
2.  Ignition switch can do this too - BTDT several times.

3. Fuel pump starvation/cavitation not as likely on S car, but will do this too.

Does sound like some sort of electrical disconnect.  I'd be looking at the fuel pump
relay and associated wiring - goes from/to Ign. Switch, X-relay, ECU, F.P. relay,
coil(s), pump, etc.  Plenty of connections under the relay/fuse panel that can be loose.

Ben


[Date: Tue, 18 Aug 2009 00:47:47 -0400
From: mike claire <mike.claire at gmail.com>
Subject: Re: [s-cars] Cutting out at speed
To: "McCall, Randy" <rmccall at nexant.com>
Cc: s-car-list at audifans.com
Message-ID:
	<d219f42d0908172147u70d8d961gfd923c2e7371ca31 at mail.gmail.com>
Content-Type: text/plain; charset=ISO-8859-1

Thanks Randy, I replaced the fuel pump about 20K ago.  I don't suppose
that's reason to rule it out.

But somebody here doubted my theory about the fuel pump relay, since the
cutout is instantaneous.  I think he's right - if the fuel pump relay cut
out (or if the pump itself were weak) the car would need a few seconds to
starve, and then die.  I wouldn't get the driveline shock I get when the
power cuts out in an instant.

Bob Myers says he had my exact problem, and it was a bad 1.8T ignition
harness.  I don't doubt him, but I don't understand how a coil harness can
fail that way - going from 5 cylinders to 0 instantly.  But I should
probably check my grounds.

I'm going to jiggle the ignition switch next time this happens.  Anybody
ever had an ignition switch give my symptoms?]