[T3] Surging and lurching! Fastback with FI

[Jim Adney]

On 26 Aug 2017 at 12:34, jaredkohler at gmail.com wrote:

> Now, out of the blue, the throttle / engine response upon take off surges
> and lurches violently.

Is the idle normal when this happens?

> I pulled the cover to my TVS (Throttle Valve Switch) to check the contacts
> and all looks as it should. Clean and making contact. I never changed it's
> position to begin with though. The FI TVS harness plug (4 wire) was also
> connected tightly.

I have a faq on adjusting the TVS, but it's almost never the problem. The 
quick check is to simply unplug the TVS and see if the problem goes away. If 
it does, readjustment, cleaning, or replacment may be called for. (Note: I 
have never had to replace one of the '70-1 4-terminal TVSs.)

> My next step will be to check the fuel presser using my fuel pressure gauge.

Probably not the problem. The fuel pressure very seldom changes. It's a set 
and forget item. On your '70, the pressure should be ~30 psi.

Check anything that might be loose in your drive train: lug bolts, CV joint 
bolts, etc. Anything that might add to backlash in the drive train can lead to 
bucking problems. Could be a worn CV joint or broken springs in the clutch 
plate.

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