Lambda Duty Cycle % question - PeachParts Mercedes-Benz Forum

TCCBass · #1 10-17-2002, 05:18 PM

On the '92 300E I have adjusted the Lambda % 3 times. It runs better. I do have to say that. HOWEVER I think something may be out of whack or just completely out.

I can get the duty cycle where it averages ABOUT 50%. I am using Larry Bible's guage and it jumps as much as 7%. Each time I have checked it has been way off the 50% to which I adjusted it the last time. Instead of stalling, it now just "coughs" when I start from a complete stop. Not consistent, just frustrating especially when cold. It will die almost every time.

I have seen in the DIY where the duty cycle was on 50%. Should mine be doing that or will the fluctuate in %. What could be out to make it do this (EHA, Throttle body, Lambda controller?).

I'm actually begninng to have hope. HELP!!!

Mike Richards · #2 10-17-2002, 05:46 PM

Check out what Steve Brotherton had to say in this post:

http://www.peachparts.com/shopforum/showthread.php?threadid=26158&highlight=50%25

TCCBass · #3 10-18-2002, 11:57 AM

Thanks for the link! Every time I check it has changed. 2 days ago I set it to between 45-50%. Then last night I checked again. It was at 30%. Do I have a bad adjustment screw that isn't holding? It runs GREAT after adjustment but just won't hold. That's the great mystery.

The few days it was running rich...could I have cooked my 02 sensor?

dpetryk · #4 10-18-2002, 12:30 PM

I had a similar problem. I could get the duty cycle set at idle but when on the freeway it would move out if range and vice versa. It turned out to be the fuel distributor. I cleaned it with brake cleaner solvent and the problem went away. Since your adjustment keeps moving I would consider the possibility of something associated with the fuel delivery system.

TCCBass · #5 10-18-2002, 02:01 PM

Dave,

You said you cleaned the fuel distributer... Did that require removing the throttle body? I hestitate to dig to far into it, but I'm definitely game. My distributer governor has been replaced. The fuel pressure regulator has not. When I press down to adjust the allen bolt to adjust Lambda the bolt tends to stick down and I must "fiddle" with it to get it back up (good southern term).
I'm all ears (eyes in this case...) as I'm going to TRY to get it solved this weekend.

dpetryk · #6 10-18-2002, 05:41 PM

My fuel distributor was easily removed. The throttle body does not have to be touched (at least on my 420's it didnt). Remove it, whatever it takes and I used "brake parts cleaner" by Albany. It is a great solvent. I sprayed it in all every place I could. In all directions possible. I shook it while the stuff was inside it. I operate the plunger and generally worked it over with the solvent as best I could. The gremlins went away. It has worked great ever since. In my case the car had not been run for 1.5 years and I presume that the fuel had left a varnish deposits inside the thing.

Good luck.