The reason its fluctuates is because the computer would be adjusting the mixture up and down all the time.. No fluctuation means computer is not adjusting. The duty cycle IS the diagnostic on these cars.. Various duty cycles mean different things.

__________________
Bill

Backyard Shadetree Mechanic, 30 years running.

1987 300TD
1988 300E (sold, sniff)
1999 S320
1981 Volkswagen Rabbit Truck (Diesel)
2001 Ford Expedition
1988 Suzuki Samurai
On my list to buy: R129, for me, and a R107 for my wife.