duty cycle drift

[Paul Meyers]

Gee, that's how mine work as well (steady at 65% until warm, whereupon they
start to control). I'm assured that they're functioning nominally when
they're "hunting" back and forth. I tried it on 2 different ECUs and
different cars and it works exactly this way.

Paul Meyers 
Gray 87 5KCSTQ 1.8bar eurolights fuchs 145 kM, needs loom transplant 
Pearl 88 5KCSTQ 1.8bar eurolights fuchs bilsteins 125 kM 2pc-em k24 turbo 
Metallic White 87 5KTQW eurolights bilsteins 191 kM daily driver
Blue 86 5KCSTQ parts car 


-----Original Message-----
From: Konstatntin Bogach [mailto:kbogach at home.com]
Sent: Saturday, December 02, 2000 7:42 AM
To: quattro at audifans.com
Subject: duty cycle drift


I was measuring FV duty cycle at different conditions (not driving) and
found strange drift. At start and cold engine it is stedy 65%. Then it
slowly moves down and at ~50% it goes to closed loop. Now it changes in
45-55 range. Bridging contact 2 and 3 on trottle switch connector (WOT)
send it to steady 62%(open loop). Looks good?
But after 10-15 min of playing with it I found that at closed loop duty
cycle is shifting toward 40-50% and stays there. What it might be?
Something causing rich running?

I did it first time and I have several questions.
I pressed repeatedly "hold" button on multimeter to see the range of
duty cycle cause it was changing continuosly on the screen. I saw posted
messages saying that people observe duty cycle while driving. I doubt
they used the same method I used. What do they use?
Another question: using same method I measured O2 sensor output voltage.
It is between 20mV and 2.2V. From what I read I expected to see ~1V as
upper value. And I though all of them has same output voltage. Any
ideas? 

Thanks.

Kosntantin Bogach
200tq 89