On Fri, 30 Jun 95 14:28:20 CDT Dan Houg said:
>Spark plugs.  There are documented cases where the only difference
>between and emission failure (with new regular electrode plugs) and
>emission pass was the installation of tri-electrode plugs.  Now
>here's the kicker:  there is not a dealer listing/vw application for
>the tri-electrode plug for the 2.1L engine.  there is for the 1.9L
>and just about every vw engine in current production but not the
>2.1L.  I can't for the life of me figure out why they dropped the
>tri-electrode from the application for this engine.  They made a
>noticable difference on my 1.9L.  I really wanted to stick a set of
>tri-electrode in my 2.1L but was scared off with thoughts of
>piston-plug clearance etc.  Somebody help me out here.

this is what i found on the 3-prongers:
        Bosch       W7CO                    W7CCO
                                            W7DTC <3-pronged>
        NGK                                 BR6ES
                                            BP6ET <3-pronged>

and i've been running the Bosch plugs not for 21,000 miles (2nd set ...
after 15,000 miles, i got a little paranoid ... the first set was NOT very
burned or used up or even rounded on the electrodes).  and it SEEMS to have
helps the idle and low end power. now, i'll be the first to admit that it's
completely subjective on this! :)

in fact, the only DOCUMENTED change since i put in the 3-prongers (Twang your
magic pronger, Froggie!) is that my AVERAGE fuel economy keeps going up!
yeah, i know ... but it kinda bothers me. the average sat at 19.4 for years
and now in the last 21,000 it's risen to nearly 19.8 ... and i didn't think
the engine should be "loosening up" (for the better) any more.

but anyway, i have the 88 2.1 liter engine and have had NO problems with
length or whatever. it's a little tricky to gap those 3-prongers, but other
than that, it's just a normal plug.

joel