[T2] ECU and larger displacement

[Dennis Gentry]

Did you use a crush washer plus the sensor ring, or just the sensor ring?
If you left off the crush washer, the plug might extend into the cylinder a
tiny bit more, making it run hotter?  If hot gases were escaping, you
should have been able to hear it, plus it would leave tell-tale marks
around the hole.  (Try running with a spark plug only screwed in a couple
of turns to see what I mean. :)

I like your hypothesis about it running lean, since too lean will
definitely cause high CHT.  Are you thinking that the injectors meant for a
1.8 L engine are failing to keep up with 2 liters of displacement at high
RPMs?  I don't think that's the cause, since (I think) the injectors were
the same from 1975 through 1979, when the stock engines became 2.0 L in
1978 or so.  You could check for too-lean and for reasonable vs. too-low
power output by putting it on a dyno and measuring the CO/O2 levels in the
exhaust, but I imagine there is an easier way to do it that I'm not
thinking of right now.

Good Luck!
Dennis



On Wed, Aug 3, 2016 at 11:46 AM, Sami Dakhlia <sami.dakhlia at gmail.com>
wrote:

> Hi,
>
> I'm back in California for the month, my annual pilgrimage to the US
> to work on my '75 bus (and see family, too :)
>
> I must admit that I'm just not enjoying the bus as much as I used to;
> it's just a big headache. Too much time spent on fixing things, not
> enough time spent traveling. Last year I installed a Dakota Digital
> head temperature gauge and the temp readings went through the roof!
>
> We suspected that the O-ring crimped on the thermo-couple didn't allow
> for a proper seal of the sparkplug, allowing hot gases to escape and
> cause the high temp readings. I've now relocated the sender, wedging
> it between the fins, not under the sparkplug. Not perfect, but a
> better solution will have to wait until the day I have to pull the
> engine.
>
> While the temp readings are no longer outrageous, they're still north
> of what's acceptable, sometimes above 380 F. And the engine is lacking
> power, even by vw bus standards.
>
> Which brings me to a new hypothesis: the engine is running lean when
> pushed to the limit (highway driving at 60mph, or climbing hills).
> It's a '75 model and came stock with a 1.8 liter engine. I have since
> "upgraded" to a 2 liter engine. I have so far assumed that the AFM
> would properly compensate for the extra displacement, but now I'm
> wondering.
>
> BTW, I also adjusted the AFM following the instructions at
>
> http://www.itinerant-air-cooled.com/viewtopic.php?f=50&t=7761&sid=26d79b8f4581a7c3219fbb1581ad5523
>
> Thoughts?
>
> Sami
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