[T3] B brain

[Bobnotch]

Right before the 2004 Invasion I had a German Blue coil go bad. The engine would run fine at idle, but put a load on it and it would fall on it's face. I went thru every system on the engine before I found it, because the engine would "run" I didn't think the coil was bad. It wasn't until I changed the coil that everything became "normal" again. Then it was a matter of swapping everything back. When the engine lit off (after the coil change) the car almost reversed thru the rear wall of my garage, before I shut it off. :O


-----Original Message-----
From: Jim Adney <jadney at vwtype3.org>
To: type3 <type3 at vwtype3.org>
Sent: Sun, Jun 10, 2018 12:21 pm
Subject: Re: [T3] B brain


On 10 Jun 2018 at 6:06, donrob at yachtsales.com wrote:

> I have seen a bad coil produce as very weak spark (especially in small one
> cylinder engines) where the engine would run, but not well. A new coil
> fixed it right up.
>
> I once had a beetle come in with an odd looking coil that didn't run
> right. Replaced it with the correct Bosch unit and it ran properly.

Yes, I've seen problems like that, too. Those are difficult to quantify and
seem more like an extreme miss than simply a weak spark. It's quite possible
to get spark when the situation at the gap is easy, so the spark can jump the
gap, but when the cylinder pressure is high, and higher pressure makes for
better insulation, the voltage can't get high enough to jump the gap.

This makes for a sort of "situational miss" where an engine may idle, albeit
poorly, but die completely when the throttle is opened.

It's certainly true that if I see a poorly running engine with a bunch of odd
aftermarket parts replacing the reliable Bosch OE parts, the aftermarket
parts get my first attention.

We also had a list member a few years ago who had been sold the taller
Beetle dist cap for his Type 3. That meant the spark had to jump a couple
rather large gaps inside the distributor in addition to the gap in the spark
plug. Since the Beetle cap is maybe 1/2" taller than our cap, it amazed me
that the engine ran at all. I don't remember the details, but I don't think it was
driveable.


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

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