Duty Cycle WAY Lean? Help!
 

Hey Guys,

My 300E has had a slowly worsening case of the SSS lately. I have also noticed that my idle is a bit low (+/- 550rpm) and had suspected a lean condition causing this (my milage has been a little too stellar of late: 26-27mpg highway... :eek:).

I just got done checking & re-checking my duty cycle with the following results were:

(All numbers below are approximate and do oscillate w/ car running. Test was done with car @ operating temp, Neg in PIN #2 & Pos in Pin #3.)

Duty Cycle with engine off - 50% (6.03V)
Duty Cycle with @ Idle - 90% (+/-1.2V)
Duty Cycle @ 2500rpms - 65% (+/-4.2V)

From what I can understand on the subject, my DC should be 70% w/ engine off for a Federal car like mine and the 90% DC @ idle indicates an incredibly lean condition. (:eek:)

What would cause the DC to be low with the engine off? Am I looking at a component failure (throttle switch sensor? crank position sensor?) or is my DC just way put of adjustment?

I have read up & learned tons on DC/Lamda function, but I have seen absolutely no mention of the DC being anything other than 70% w/ the engine off... :confused:

Thanks!

Surely someone has to have experienced a Duty Cycle reading off of 70% with engine off?

Paging stevebfl...



:D

I'd have to plead ignorance and query, what the hell is a 'duty cycle'?

Hey Cliffmac,

Duty Cycle is a more or less the measurement of the mixture control in a KE Jetronic FI system (as it relates to this application anyway). Here's a quick breakdown:

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