Date: Tue, 26 Jan 1999 00:37:53 EST
Reply-To: Modl6971@AOL.COM
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Michael Modl <Modl6971@AOL.COM>
Subject: Reply, [syncronized] Question
Content-type: text/plain; charset=US-ASCII
In a message dated 1/25/99 6:08:05 AM Pacific Standard Time, tbednark@ford.com
writes:
<< I've always had trouble with my Syncro during warm-up, bucking, poor
acceleration, etc. but if I just let it warm up in the driveway,
it's OK. Warm and hot starts have been quirky too, but at 191,000
miles, I cut her some slack. Recently, though, warm starts have
become a real problem. This typically happens 1/2 to 4 hours after
parking it. The engine starts properly, but then it falters and
sputters. Usually, the engine just dies immediately. It always
restarts, but then stalls again. Holding the accelerator at part or
full-throttle doesn't help. During the whole episode, the exhaust
smells rich. Disconnecting the cold-start injector didn't help
(didn't make it worse, either). If I can manage to keep it running
for about 1.5 to 3 minutes, or restart it repeatedly, it smooths out
and then runs properly. Cold start is still OK (as long as I let it
warm-up).
The fuel pump was replaced at a dealer about 5 years (50K miles ago).
Fuel filter about 4 years ago. Injectors/seals and the coolant temp
sensor last summer. O2 sensor (3-wire) was replaced about 2-3 years
ago. I checked out the fuel-pump relay for evidence of
overheating/burned contacts/broken solder joints (no problems). I
have some suspicions that it could be related to the differential
pressure regulator. I had a problem with it before, but was able to
resolve it by flushing it out with brake cleaner (I can imagine what
Bosch wants for that part . . .). I tried flushing it out again this
time, but it didn't help.
Any thoughts on this? Rear-wheel-drive and a V8 is a drag in snow .
. . >>
First of all, find out if your cold start valve even works. With a cold
engine, remove the valve without disconnecting the fuel line, briefly start
the engine, fuel should spray. Do this carefully, no fires please. If it
doesn't spray, email me back, we'll worry about it later. On your hot start
problem, this is so so common on all CIS fuel injected cars. You are loosing
fuel pressure while the engine is off. It's being lost at the tip of the
injectors. The fuel is vaporizing or boiling in the tip of the injectors. A
fuel pressure test wont show this minor fuel psi drop. If the injectors are
the original in this car with 190k on it, it's time for new injectors anyway.
Replacing them will give you usually about an 80% improvement on the hot
restarts. Injectors aren't cheap either. $40 or so each.
Has the frequency valve been properly set at the fuel distributor? It's
supposed to be set at 50% duty cycle or 45% dwell, (runs best at 45% duty
cycle or 40% dwell). A VW specialist, one that's been around many years can do
this. There may be carbon on your valves too, soaking up the fuel on start
ups like a sponge, it leaves no fuel left in the combustion chambers. One can
of Lubro Molly valve cleaner (ventile sauber is written on the can, it german
made) slowly sucked in the intake manifold through a vacuum hose will usually
clean up those valves pretty well. Or dump a can of the same and also Lubro
Molly injector cleaner in the gas tank when the gas tank is almost empty, and
drive the shit out of the car. It cleans those valves pretty well. Add a can
of both again to a full tank of gas.
You mentioned the warm up regulator too. It should be checked for proper COLD
CONTROL PRESSURE with a cold engine. It should be around 18 to 22 psi, or 1.4
bar.
Have fun, see ya, Michael
87 vanagon syncro
87 5000 quattro
past auto's
93 passat VR6
93 corrado VR6
88 quantum
89 golf
86 golf
89 audi 100
81 jetta diesel
81 rabbit diesel
84 quantum
87 scirocco 16V
82 scirocco, race car
80 scirocco
83 audi 5+5
81 BMW 635 csi euro model, rare
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