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Re: Hot starting problems ur-q
> The cold start injector is controlled by a relay under the dash. >(actually behind the door in the drivers storage tray.
> those with the fuse box in the engine compartment (I'm jealous) I >don't know where your cold start injector relay is.
> You can determine which one it is by starting the car when is is hot >and feeling the relay click on and off about every 7-8 sec.
> Now remove the relay and remove the cover. Near the top of the >circuit board there is a component with a silver dial. Adjusting this >dial will regulate the length of the cold start injector pulse. It >worked well on my car and I no longer have a hot start problem and it >did not create a cold start problem.
The relay you refer to is the "Hot Start Pulse Relay" which according to
the early service documentation is the relay next to the fuel pump relay
(on the left) under the dash as you described. For identification
purposes, the relay part number shown is 813-906-064, Terminals 31b
(green/white wire to cold start valve) , 31 (ground) and 50 (red/black
wire from ignition switch) are used.
When the engine is cold the cold start valve operation is controlled by
the thermo-time switch which is screwed into the cylinder head, after
the car warms up and the thermo-time switch is out of operation, this
"Hot Start Pulse Relay" has the capability to turn on the cold start
valve during engine cranking.
During the early 1980's the VW's and Audis had some Hot start problems
and this Hot start pulse relay was added to "help" the hot start
problem. On the ur-Quattro it came that way from the factory, the hot
start relay is wired in parallel with the thermo-time switch so either
the relay or the thermo-time switch can turn on the cold start valve.
I wasn't aware of the adjustability inside this Hot start Pulse Relay,
thanks a bunch for the information....