Re: (16v) Thermo-time Swtich

[Bill.Scarince@tenneco-automotive.com]

Toby,

You said that you verified by using a test light at the wiring harness that the
cold start valve is getting the proper signals, right?  And you also verified
that the cold start valve is operating when the voltage is applied to it.  So
considering that, I don't understand why you conclude the thermo-time switch is
bad when you've just verified that it's not.

That aside, the symptoms you describe sound more like the control pressure
regulator or some other problem that causes you to be too lean when cold.

Before worrying about that, follow the Bentley procedures to verify that your
air-flow plate is adjusted properly, and verify the signals to the idle
stablizer valve.

If all that checks out, then check the spray pattern on all your
injectors.....replace the seals if they are hard/brittle.  Be sure your ignition
system is in good condition.

If all that checks out, then it's time to check the system pressure.  Good luck.

Bill

----- Original Message -----
From: <archive@porknet.fdns.net>
To: <scirocco-l@scirocco.org>
Sent: Sunday, April 02, 2000 4:36 AM
Subject: [16v] Thermo-time Switch


> Hi,
>
> I've been having a cold running problem since I bought my car, an '87 16v.
> The car will take two to four attempts to start, and finally stop
> stumbling after much urging from the gas pedal, but as soon as I let off
> the gas, the idle dips down to 300-400 rpm and the engine sometimes dies.
> After I let it warm up for 30 seconds, I can drive if I rev it to 3000 rpm
> and baby the clutch. For the next 2 minutes of driving, it will die as
> soon as I let it idle pulling up to a stop sign or otherwise. Throttle
> response is very slow and the engine doesn't have much power.
>
> I've attempted to diagnose this problem before, but this time I was
> looking at the cold start valve. I removed it from the intake manifold
> port and noticed that it had a bit of corrosion under the carbon buildup
> on the injector tip. I followed bentley's instructions aiming it into a
> transparent container and cranking the engine. Nothing came out. Finally I
> connected it directly to the battery and after about a second it began
> spraying fuel. After that initial delay, there was no other delay when I
> disconnected it and reconnected it again. The fuel spray was atomized and
> cone-shaped, everything looked good. I bolted it back up.
>
> So I began troubleshooting the wiring. Here is a simplified version of
> what Bentley has for my wiring. The G/W is green wire with white line,
> R/BK is red wire with a black line, etc.
>
>                                       +---internal ground
>                                       |
> +---------+        +--------------------+
> | starter |--R/BK--| thermo-time switch |----G/W----+
> +---------+        +--------------------+           |
>      |                   +---------------------+    |
>      +--------BK---------| cold start injector |----+
>                          +---------------------+
>
> Both the signals from the starter seem to supply +12v when the starter is
> cranking only. I used a test light at the wiring harnesses for the cold
> start valve and thermo time switch and these circuits are both operating
> correctly. I used a continuity meter on the green/white wire between the
> thermo-time switch and the cold start injector and it tested out okay.
> This only leaves two possibilities: a bad ground at the thermo-time switch
> or a bad thermo-time switch. A bad ground is unlikely since the
> thermo-time switch itself is threaded into the block. So I probably have a
> bad thermo-time switch.
>
> The thermo-time switch, as far as I can understand it, is a thermally
> controlled switch that opens above a certain temperature. It is surrounded
> with an electric heated element and it is also threaded into a hole in a
> coolant passage. Above a certain coolant temperature, the switch is always
> open. Below that temperature it is closed. When the starter is actuated it
> stays closed until the heat from the electric element warms the switch and
> opens the circuit to prevent flooding.
>
> So, who has replaced one of these before? According to Bentley I'll have
> to drain my coolant by removing the lower radiator hose. This is fine
> since I don't think it has been changed for at least 2 years. Where can I
> get the good phosphate-free coolant?
>
> I think the hardest part will be getting a wrench on that sucker. It is in
> a nice convienient spot right below a coolant hose.
>
> Speaking of which, I need to replace the coolant hose that runs from the
> block to the coolant bottle. I think this is the one right above the
> thermo-time switch. What is the official name and part number for this
> hose and where can I get one for a reasonable price?
>
> Any pointers would be appreciated.
>
> Thanks!
>
> -Toby
>
> --
> '87 16v silver
>
> --
> Email problems to: scirocco-l-probs@scirocco.org  To unsubscibe send
> "unsubscribe scirocco-l" in the message to majordomo@scirocco.org



--
Email problems to: scirocco-l-probs@scirocco.org  To unsubscibe send
"unsubscribe scirocco-l" in the message to majordomo@scirocco.org