[Vwdiesel] 1.6L cold start-idle speed?

[Sandy Cameron]

At 09:29 AM 10/11/04 -0400, you wrote:
>I was monkeying around with my cold start knob (at the pump end) and didn't
>find any difference in idle speed moving the mechanism back and forth about
>3/4" in either


!.. they did not put fast idle on those until 86 or 87

2. No, it wont harm it to run with the knob out.

All it does is advance the injection timing slightly at start up.
Once the engine is running, the transfer pump pressure inside the pump does
the same thing, and the knob has no further effect.

Now, the fine facts:
 Once running, the transfer pump pressure rises and takes over at about
1200-1500 rpm, advancing the timing.
At idle, 800-1000 rpm, the knob still has a slight effect on injection
timing, but not speed on your car

If you have the hood open, and stand beside the car, reach in through the
window and pull and push the knob, You should be able to detect a slight
increase in the clatter with it pulled out (advanced injection)

Also, sitting in the car with the engine idling, using sensitive brain
surgeon fingers, as you pull the knob out, the first bit of travel, you
should feel nothing. Then you will meet some slight resistance, accompanied
by feeling the injection pulses as you pull. This point is where you have
got ahead of the automatic advance, which is doing little or nothing at idle.

If you repeated this test while driving at 2000rpm, you would not feel the
pulses, as the auto -advance has advanced the injection beyond the range of
the start knob, and it now does nothing when pulled out.

This will not work as well on post-87s, as the fast idle mechanisim will
bring the engine speed up as you pull it out, raising the pressure and
taking the auto-advance ahead of you as you go.

Hagar has explained all the above in his hillbilly tuning articles.

Sandy

Sandy