Fuel consumption

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sean sherry

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An interesting experiment from here to Newcastle and back, fiddling with the ignition Timing. The Air Con system has a retard device fitted to the Distributor which operates at all times with the Air off and is disabled when the Air is operating. That is , the timing is advanced about 5 degrees as soon as the compressor kicks in to speed up the idle, and prevent stalling with the extra load from the compressor. The vacuum to the retard fluctuates with engine vacuum per the engine load. So I plugged the retard vacuum line going to Newcastle which increased the timing at all times, and then reconnected the retard side coming back. Consumption to Newcastle was a respectable 26.5 MPG and returning it was 25.4
No difference, as I had the Air Con on all the way back as it was a very hot day. Also I was driving 5 to 10 Ks P.H. faster most of the way.

Moral to the story is that Mercedes Engineers know a lot more than I do !

Also changing the Vacuum upsets the Auto Trans upshifts on light throttle.
Tends to cause slight flaring due to higher vacuum . My 3/4 shift is marginal at the best of times when cold.
 

Michel

The Prince of Arabia
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And the moral of the story is:
If it ain't broke don't fiddle with it ;)
 
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