[T3] ? on dist drive

[William J]

What you are calling spring contacts I refer to as a forked switch.

 My switch reads out fine with an ohm meter. Somehow I get the feeling that 
no injection or shut off is not so great even though the timing drops , not 
insant so you have spark and no fuel . Seem's like a bad idea in stop and go 
traffic.

  It does seem to me that the pin 17 has an affect on idle as well as the 14 
has with fuel shutoff . All I can say is those 2 terminals were real loose 
and now that they are now things have changed , it's better. I never took an 
ECU apart other than to look inside one with the lid off. The result I got 
leads me to believe there is more to it as far as what the ECU compensates 
for and when.
----- Original Message ----- 
From: "Jim Adney" <jadney at VWType3.org>
To: <type3 at vwtype3.org>
Sent: Wednesday, August 17, 2016 8:44 AM
Subject: Re: [T3] ? on dist drive


> On 16 Aug 2016 at 20:19, William J wrote:
>
>>  What about pin 17 ? There are three wipers or slidding contacts . One 
>> that
>> that runs on 12 and 14 and 17 . On decell the forked switch is the 
>> contact
>> on accel the forked switch position contacts for the full load .
>
> 17, as you suspected, controls the shutoff during coastdown
> (overrun.) The double contacts on 14 bridge the gap, allowing contact
> between 14 & 47 (47 is ground, or common, for all these
> contacts/functions.) In normal operation, on the car, the shaft can't
> rotate far enough for the double contacts to both cross the gap
> between 47 & 14.
>
> It's also important to notice the spring contacts at the end of the
> wiper arm. One contact disables the alternating ("throttle pump"
> contacts if the throttle is closing; the other disables the idle
> contact if the throttle is opening.
>
>>  If the injecotrs do not shut off on decell then wouldn't the
>> fuel still be injected and cause un burnt fuel to burn in the heat of the
>> exhaust.
>
> Possibly, but keep in mind that you'll still be getting spark.
>
> Some California cars in '72-3 came with a damper that slowed the
> closing of the throttle so that you'd keep injecting for a short time
> during overrun. Apparently, that produces less emissions than cutting
> off injection quickly.
>
>>  I just find it odd that suddenly after tightening the TPS terminals the
>> popping out the exhaust no longer happens. All the other FI terminals 
>> needed
>> to be tightened yet were no where close to as loose as 14 and 17 .
>
> I don't see how loose 14 or 17 would cause any problems, either.
>
> A loose contact on any of the other 3 could mimic the "throttle
> valve" contacts, however, and might create extra injections.
>
> Note also that the '73 TVSs have a tendency to develop tiny cross
> contact shorts between 20 and 9. Check this with an Ohmmeter: connect
> it between 20 and 9 and slowly open and close the throttle. If you
> see any twiches of the Ohmmeter needle, try cleaning the spaces
> between the little interdigitated gold 20 & 9 contacts. If you can't
> get rid of this, you'll need to replace the TVS, or disable those
> contacts by putting a bit of insulating plastic under the 2
> stationary spring contacts that connect the board to the connector.
>
> -- 
> *******************************
> Jim Adney, jadney at vwtype3.org
> Madison, Wisconsin, USA
> *******************************
>
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