Timing Advance Was: Exhaust whistle and rough idling when

Archives of Posts to the NZ MX5 List back in 2006
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MadMaz
Need, more, 5-ing, time....
Need, more, 5-ing, time....
Posts: 100
Joined: Thu May 18, 2006 10:56 pm
Location: Pukekohe

Timing Advance Was: Exhaust whistle and rough idling when

Post by MadMaz » Tue May 02, 2006 5:46 pm

Hi Peter

That's an interesting point you've raised here - I've heard the same thing
discussed about increased fuel consumption when advancing the timing. I've
done this for many years with all my cars - & always running the maximum
octane rating of fuel I could get.

Advancing the timing provides more "pep" or pick up, especially in the low to
mid rpm range with fuel injected performance DOHC's. On the open road cruise,
a notably lighter throttle is required to maintain 100 km/hr. I've always
experienced better fuel consumption using a light right foot after advancing
the timing.

But...and speaking from experience...a peppier engine does encourage the
driver to drive a bit more spiritedly around town and through the bends on the
open road using more fuel. However, driven properly with a light throttle,
I've always experienced a 2 to 3 mpg improvement in economy (town/country
cycle) with cars in the 1600cc to 1800cc capacity range.

Advancing the timing within the proper parameters (i.e. not to the point where
the engine "pinks" or knocks) actually makes the engine more efficient by
producing more power for very drop of fuel burned. But use a heavy right foot
and the engine will respond quicker, rev harder and use more fuel at the
limit.

Case in point: Mazda 1.6 DOHC Astina I've had for years & have always
monitored the fuel economy fairly accurately (has the same 1600cc B6 engine
block & head as the NA MX5).
*Mileage before timing advance: Town/City cycle; 31 mpg Long
Trips; 38 mpg Hard driving; 31 mpg
*Mileage after 12 degree timing advance: Town/City cycle; 33 mpg Long Trips;
41 mpg Hard driving; 29 mpg

More economical when driven normally - but less economical when driven hard or
spiritedly (& especially on the track recorded as low as 23 mpg!).

And yes, opps, an error in my "tuning up message" - I forgot that the MX5 runs
the leads straight from the coil to the plugs - there's no distributor cap -
unlike it's Astina B6 1.6 & BP 1.8 engined cousins! Sorry about that!

SuperCheap Auto has MX5 NA plug lead sets for $99 and NGK BKR6E11 plugs for
$6.00 each - cheaper than Repco or your dealer - but someone on the List might
know of a better buy somewhere else.

Cheers
Mark
Firm Believer in 98 Go Juice - Go for it!

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