Duty cycle 84%? What does this mean? - PeachParts Mercedes-Benz Forum

haasman · #1 02-20-2005, 05:45 PM

Got a multi-meter with a duty cycle. Followed instructions, red in #3 black in #2 in the test socket on the 91 300e.

Turned on the ignition, but before starting 84% reading and even after the engine is running I still get 81%. The value does not fluctuate.

-Does this mean the oxygen sensor is bad? or .....

-Does this mean the air/fuel mixture adjustment is off the charts?

Haasman

BenzMatic · #2 02-20-2005, 06:43 PM

Did you let the car reach the normal operating temperature before you took the reading?
If it is taken on a normal operating temp. I believe you are running lean, your fuel consumption should be way off also. You should be able to adjust the mixture, as for Oxygen sensor is concern, this alone should not be the determinig factor. Do the test on the sensor itself, there is a procedure out there on these threads for that.

You might already have them but just in case Few good readings on duty cycle
'86 300E rich mixture - Duty cycle help

http://www.peachparts.com/Wikka/EngineControls

http://www.landiss.com/mixture.htm

Hope this is helpul.

haasman · #3 02-20-2005, 09:02 PM

Went out and got it warm and it still reads 81.3-81.7% on the duty cycle setting.

I tried turning the 3mm both clockwise and counter clockwise but didn't influence the read out at all.

Am I so out of range that I am getting this reading? If so which way should I turn the adjuster?

(Below is the meter I bought from Sears for $29.95)

Thanks,

Haasman

A264172 · #4 02-21-2005, 12:49 AM

To which car are you referring? Year/model make a difference for this.
I believe you have a California car (which is indicated by 85% duty cycle at X11 between terminal #3 [+] and terminal #2 [-] with: ignition on engine off)

From my reading of the CD (and I may have this wrong).
You will have to read faults at X92 terminal (near battery) with an LED pulse counter like Arthur Daltons: http://members.aol.com/ajdalton7/ledtool.jpg

It could be that: Only once a pulse reading is taken can you test duty cycle at X11?

But if your Duty cycle reading means something it might be this:
80%
Open circuit or short to ground.
Air intake temperature sensor (B17/2) faulty
Altitude correction sensor (B18) faulty
Test Air intake temperature sensor.
Test Altitude correction sensor.

haasman · #5 02-21-2005, 01:33 AM

Marty

Thanks, I edited my original post for which car (91 300e). Sorry about that.

Seems like a long list .... I will check the codes and report back after I make an "Arthur Daltons Special Tester".

The engine must be running too lean because it stumbles in throttle transition from idle to mid RPMs. At a sustained RPM seems fine.

Haasman

romansek · #6 02-21-2005, 11:53 AM

Are you sure your meter is set for duty cycle (%) not for frequency (Hz)? Upper left button change between duty/frequency.

Roman

haasman · #7 02-22-2005, 12:26 AM

Roman

You were correct. So I changed the button and got percent instead of Hz but still the same except the reading hovers at 90.x%. Twisting the allen either way makes no difference.

How does one determine if the O2 sensor is bad?

Thanks for the help here.

Haasman

A264172 · #8 02-22-2005, 01:08 AM

Test Conditions
Battery voltage 11-14 V,
Engine oil temperature approx. 80°C
Engine idling

90% = Current to electrohydraulic actuator (Y1) implausible....Test electrohydraulic actuator

haasman · #9 02-28-2005, 01:13 AM

Quote:

90% = Current to electrohydraulic actuator (Y1) implausible....Test electrohydraulic actuator

Marty, what does this mean?

This weekend, BTW, I replaced the O2 sensor. For the first time it registered around 40 until warmed up and then hovered around 90%.

I purchased the Arthur Dalton LED tester parts from radio shack. Could you point me towards how to use it to determine the codes you spoke of?

Thanks,

Haasman

A264172 · #10 02-28-2005, 01:36 AM

I am away from my CD until tomorrow evening at work.
I will try looking up the procedures then and check back on the thread.
In the mean time you might want to use search to familiarize yourself with it.
I think your car... now that I recall... California cars have a push button led near the battery to display faults.
Also maybe someone with experience will chime in.
Till tomorrow...good luck.

"90% = Current to electrohydraulic actuator (Y1) implausible....Test electrohydraulic actuator"
From what I recall... You may have to be dirving car to measure this properly... or it could be going south.

A264172 · #11 02-28-2005, 02:29 PM

Haasman,
Just to clarify... You have an M103 engine?

haasman · #12 03-01-2005, 04:43 AM

Marty

I am actually working on two cars ..... a 91 300e and the 87 190e 2.3.

The one that the thread is about is the 300e.

Haasman

A264172 · #13 03-01-2005, 05:42 PM

(These are JPEGS coppied from the factory manual, you can copy them into MS Word or something else and print them out but the text cannot be edited.)
Here are some pictures from pages in the manual that may help:

A264172 · #14 03-01-2005, 06:00 PM

And some more:

A264172 · #15 03-01-2005, 06:03 PM

Let me know if these help or if you need any more info. (The document they are taken from is almost 200 pages long.)
Here is the last one:

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