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Old 06-22-2010, 10:49 PM
Rahulio1989300E's Avatar
Rahulio1989300E Rahulio1989300E is offline
V10s & V8s FTW!
 
Join Date: Jan 2005
Posts: 1,147
Duty Cycle Issues

Hello,

I started an earlier thread regarding my emissions results. It was determined from the result that the car was running rich. High CO and HC levels with a low Nox level.

I connected my multimeter to the X11 ports 2 and 3. I put the negative (black) lead into pin 2 and positive (red) lead into pin 3.

When the ignition is turned to position 2, I get a reading of 30.7%. I have no idea what this means???

The pins are really confusing me since if I swap the red and black probes between pins 2 and 3, the duty cycle is now 70% which would indicate a federal car.

The way it is now:
When I start the car from cold, the duty cycle is 49.3%. Then after some time with the engine running, the duty cycle starts to fluctuate between 45%ish and 60%ish.

To get to this point, I did some adjustments to the mixture screw, a fair amount (1 full turn) of CW movements from which I understand is actually supposed to enrichen the mixture...

So as you can tell, I have no idea why this is occurring...

Weird thing is that when I hold the engine at 2500RPM, then duty cycle slowly but surely works its way to 0.00%. Which means the car is leaning itself out?
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2006 BMW M5 "Heidi" @ 109,000 miles
2005 MBZ C55 AMG "Lorelai" @ 165,000 miles
1991 MBZ 300E "Benzachino II" @ 165,000 miles
1990 MBZ 500SL "Shoshanna" @ 118,000 miles

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