M116 Dutycycle checking

[mathew]

Ok guys is there any way to check the duty cycle from the ECU of my 420SEL without an O-scope? I have a slightly lumpy idle I mean ever so slight, if the aircon is on you don't even notice it (slightly higher RPM).
Cheers Mat

 

[Styria]

Hi Mat, an O-scope would probably be the most efficient means of checking the ECU - especially if there happens to be an ever so slight malfunction of any component. It could be an irregularity with a number of components - leads (you could use an ohmmeter to check for resistance), suppressors (same procedure), spark plugs (clean or replace), distributor cap and rotor button.

The 'O' scope will give you cylinder comparisons as well as the function of electrical components, but I suspect you may need a competent mechanic that can actually evaluate the readings provided by the 'O' scope. Keep us posted if you can regarding any future findings. Regards Styria

 

[SEL_69L]

I think the correct oscilliscope graphs should be in a W126 maintenance manual.

Can the appropriate pages of the maintenance manual be obtained from a website?

 

[mathew]

Thanks guys, I managed to get a complete set of new HT leads (Bosch) out of America delivered for $130 OZ and the problem I had is now gone. The car is super smooth, starts easier and pulls like a German V8 should, God I luv this car!

Cheers Mat

 

[Styria]

Thanks guys, I managed to get a complete set of new HT leads (Bosch) out of America delivered for $130 OZ and the problem I had is now gone. The car is super smooth, starts easier and pulls like a German V8 should, God I luv this car!

Cheers Mat

Mat, it's missing the stum pulling torque of the 6.9 - all of 550nm at three grand from the "dirty" engine - do you remember our little trip down to the Southern Highlands, and when we started from, was it Liverpool somewhere ? Regards Styria

BTW - dare I pat myself on the back by suggesting leads and/or suppressors - so many times I have said that those items should be the ones to be checked first - each and every time, as well as the fuel filter, clean the inside of the dizzy cap, shine up the tip of the rotor button and whack in a set of new plugs - 90% of the time that takes care of most issues.