[T3] gas mileage, voltage, etc.

[Jim Adney]

On 21 Jun 2017 at 8:45, Daniel Nohejl wrote:

> I didn't check the resistance of each wire. Rather, I checked that
> each wire was firing last time I had the timing light hooked up.
> Wouldn't an intermittent miss also show up under load and not only
> periodically at idle? General driving is fine and responsive as always
> though I should maybe add this one irregularity: three times last
> week, I experienced a slight bit of hesitation or a miss when trying
> to accelerate hard up the steep portion of a bridge in 2nd. It wasn't
> quite as jarring as a full miss but felt like slightly more than
> hesitation. But I drive that bridge sometimes twice a day and it
> didn't occur regularly and hasn't shown up since last week.

In order for ignition to occur, a spark has to jump the spark plug gap. This is 
most likely to fail when the fuel mixture pressure in that gap is high, because 
high pressure makes a better insulator.

I agree that it's unusual to have a problem at idle but not under load. OTOH, 
going up the steep portion of that bridge is under load. So I recommend 
checking the resistances of the SP connectors. An open resistor here can 
lead to an intermittent miss and poor gas mileage.

BTW, in recent years, most of the spark plugs made for our cars have a 
resistor built in, so the resistors in the SP connectors are now redundant. 
For anyone now using resistor type plugs, I have non-resistor SP connectors 
which work just fine with them, and eliminate this potential problem. Putting 
the resistor in the plug means that you get a new resistor with each plug 
change, so they should never give a problem.

-- 
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Jim Adney, jadney at vwtype3.org
Madison, Wisconsin, USA
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