[T3] Engine Craziness (was Dwell Meter...)

[Jim Adney]

On 26 Feb 2012 at 7:20, Tony Rongey wrote:

> - When cold the engine starts immediately, but will die if I let the RPMs drop 
> below about 1400.
> - After a few minutes, when the engine is about half warmed up, it will cough, 
> sputter, and probably die if RPMs drop below 1500.  After it dies it restarts 
> easily.
> - Once the engine is fully warmed up it runs great and idles pretty well.  If it 
> shut it off at this point I'll have to crank for at least half a minute before 
> it will start, and if I'm making multiple stops around town then every restart 
> is harder than the one before.
> This behavior has been consistent on three or four trips since I got it running 
> again.

I've had more time to thing about this, and I'm reminded that you 
said this car has a '69 FI system. In that case, I suspect that 
you're experiencing bad grounds for the injectors, causing cylinders 
to miss as the heads heat up and the injectors lose their grounds.

On '68-9 FI cars, the injectors each have one side going to ground 
via a single ground connection to a screw into the head, near the 
injectors. Heat cycling makes this connection become intermittent and 
this may be your problem. I suggest that you find those wires and 
loosen and retighten that screw. This WILL NOT be a permanent fix, 
but it should make the engine run better temporarily. If this 
improves things, I have special washers that you can put under the 
screw heads to cure this permanently.

Look for those screws, tighten them, see if it helps, and email us 
back the results. Even if it's not clear that this is the problem, I 
still recommend that you install these special washers. They are 
cheap.

Everyone out there with a FI 68 or 69 should install a pair of these, 
even if you don't think you have a problem.

VW changed things in '70, moving the ground wires to the center of 
the case, where the heat cycling is much milder. These later cars do 
not have this problem.

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