Proper setting for Lambda - PeachParts Mercedes-Benz Forum

Cigar Havana · #1 09-07-2004, 11:51 PM

What is the proper duty cycle % for the lambda on a 1989 420 SEL? I have X11 socket pin 2 to negative and pin 3 to positive and idling hot, a reading between 40% to 50%. Is this correct or should it be changed? Do I have to unplug some vacuum line when setting the lambda?

BenzMatic · #2 09-08-2004, 02:48 AM

~50 % is the right settings. The car should be on operating temp., do not need to unplug any vaccum line. It sounds like you are ok, but if any adjustments need to be done, an interval of 10 - 20 sec is advisable. Use a 3 mm allen to do the adjustments.
Is there a problem with the car or just playing with your new $ 11.00 sears multi-meter

I hope it helps.
Good luck.

Cigar Havana · #3 09-08-2004, 08:07 PM

Yes, this time I was playing with my new toy, the Sears multimeter. Great price, great machine! Last weekend I also got a set of crowfoot flare nut wrenches so I can torque those fuel injection line nuts just right.

In about 2 weeks I'll have my hex drives and then I'll have enough courage to tackle replacing all of the intake manifold O rings, gaskets, vacuum lines from the throttle control valve, control linkage springs, and the throttle control valve sensor. I just want to make sure I can put it all back together, and get it working perfectly. I'm thinking the lambda will have to be reset after the preceding is replaced?

Are there any other parts that I should be replacing when I have the intake manifold off? I'm thinking for a DIY, this is about a 10 hour job? Comments?

Duke2.6 · #4 09-09-2004, 01:39 AM

I like an idle setting of about 45 percent as I believe this will yield better cold start and driveoff being as how less than 50 percent means the basic setting is a little rich of stoic., so it sounds like yours is right on.

Duke

BenzMatic · #5 09-09-2004, 02:50 AM

I guess It will not hurt to check lambada again after all the repairs, in theory it should be still the same.
How about changing the "air tubes" and seats for the injectors. Since you will have everything removed it would be easy to change these. I know mine are very hard and brittle, 17 years has taken a toll on these and I am always afraid to work around them. I will change them one of these days.

Good luck on all of your repairs.

Cigar Havana · #6 09-09-2004, 10:41 PM

I changed the air tubes last year, along with the injectors, and theirs seats. The new air tubes are a lot easier to install than removing the old air tubes. Just cut the old tubes into pieces. Also use some silicone lube on the air tube connections, and buy new connectors and air tube end plugs. The air tube job looks scarey at first but its quite easy, and very inexpensive.