1984 GTI Rabbit dwell air/fuel mixture readings

Hi

I took an analog dwell meter and connected it to the test connector near the
cold start valve. Thinking about it I didn't consider polarity, so I am not
sure if I measured positive or negative duty cycle. Negative duty cycle is
the time the signal is low.

On the 4 cylinder setting the dwell bounced between 36 and 40 degrees. The
duty cycle would be the dwell reading divided by 90. So the measured duty
cycle was 36/90 = 40 % and 40/90 = 45%. So 40-45%.

This was measured at an idle rpm of around 1100 rpm.


Is this slightly on the rich side? Should I leave everything alone?


The reason I checked this was yesterday I unplugged and replugged alot of
the connections such as the o2 sensor, all the connections to the coil, the
cold start valve, thermo time switch, aux air regulator and the oxygen
sensor thermo switch. I also pushed in on the injectors. The reason I did
this is because the car is old and thought that some of the connections
might be slightly oxidized and not making good contact.

The result of the above is that I have a higher idle and tons of power and
tons of throttle response. The car has tons of power now. I checked the
timing and it is dead on. I thought that something might have failed and
that the car was running super rich.

The car starts fine cold and hot.

At first I thought something must have failed but thinking about it maybe I
fixed something. The car has been sluggish and I got use to it, now there
is tons of power and throttle response.

I will check a few additional things like the aux air regulator to be sure
that it closes when it warms up. I will also check to see the idle speed
boost switch is off and not adding more air into my intake. Not sure if I
should bother to measure the fuel pressure both hot and cold. I guess if I
am anal enough I would.

Any ideas?

Thanks
James

Sounds like you made good progress. ;-)

But you need to get that idle down under 1100 rpms.
Did you try just adjusting the idle speed screw?

Not sure what your question is besides is it too rich. :-(
You will need to check the duty cycle with the engine closer to proper idle
speed.

Sometimes vacuum leaks can occur especially at the fuel injector seals. Try
spraying some carb cleaner at them with the engine running to see if the
idle speed changes.
--
later,
dave
(One out of many daves)

"Tube Audio" <murphysf (AT) hotmail (DOT) com> wrote

Hi

I took an analog dwell meter and connected it to the test connector near
the cold start valve. Thinking about it I didn't consider polarity, so I
am not sure if I measured positive or negative duty cycle. Negative duty
cycle is the time the signal is low.

On the 4 cylinder setting the dwell bounced between 36 and 40 degrees.
The duty cycle would be the dwell reading divided by 90. So the measured
duty cycle was 36/90 = 40 % and 40/90 = 45%. So 40-45%.

This was measured at an idle rpm of around 1100 rpm.


Is this slightly on the rich side? Should I leave everything alone?


The reason I checked this was yesterday I unplugged and replugged alot of
the connections such as the o2 sensor, all the connections to the coil,
the cold start valve, thermo time switch, aux air regulator and the oxygen
sensor thermo switch. I also pushed in on the injectors. The reason I
did this is because the car is old and thought that some of the
connections might be slightly oxidized and not making good contact.

The result of the above is that I have a higher idle and tons of power and
tons of throttle response. The car has tons of power now. I checked the
timing and it is dead on. I thought that something might have failed and
that the car was running super rich.

The car starts fine cold and hot.

At first I thought something must have failed but thinking about it maybe
I fixed something. The car has been sluggish and I got use to it, now
there is tons of power and throttle response.

I will check a few additional things like the aux air regulator to be sure
that it closes when it warms up. I will also check to see the idle speed
boost switch is off and not adding more air into my intake. Not sure if I
should bother to measure the fuel pressure both hot and cold. I guess if
I am anal enough I would.

Any ideas?

Thanks
James