[T3] cool weather idle hunt

Jim Adney jadney at vwtype3.org
Wed Jan 11 20:30:40 PST 2017

On 11 Jan 2017 at 20:35, Keith Park wrote:

> that FI relay screw is a often forgotten weak spot that can leave you hung,
> I remember Russ getting a great deal on a car once because of that....

This much is correct. So far, so good.

> if its loose it can have a high resistance, that would effectively give the
> electronics a low system voltage, could be intermittent and have different
> effects over the warmup curve, not noticable as much at speed but way too
> rich at idle.

Sorry, this is all wrong. That wire is the ground for the FI main 
power relay. All the FI cars have it exactly like that. Since it 
operates the relay, it's an all or nothing situation: The relay will 
be either open or closed. If the ring lug loses that gound 
connection, the relay will open and the FI will stop getting power. 
That would generate a click from the main power relay as well as a 
click from the fuel pump relay, which will also drop out as soon as 
the FI system loses power.

It would be nice to think that this fixed Daniel's problem, but it 
seems unlikely since he heard no clicks when his problems happened. 
OTOH, the clicks can be hard to notice in the middle of an engine 
dying in traffic.

As far as the position of the relay is concerned, when new, it was 
mounted so that the terminals pointed straight down. This makes the 
screw easy to access, but the terminals hard to see. It sounds like 
yours has been bent upwards to make the terminals easier to access. 
You could add a #6 external star lockwasher to make that connection 
more secure. VW may have done at at times; I'm not sure.

VW used the same relay for the rear window defroster in some years, 
and the fuel pump relay is the same in all years. I've got a dozen or 
so good used ones here if anyone needs one.

Jim Adney, jadney at vwtype3.org
Madison, Wisconsin, USA

More information about the type3-vwtype3.org mailing list