Re: Tools and a problem

["Rich Wagner" <drsavage@xxxxxxxxxxxx>]

Eric wrote:

>Now the problem: I'm failing emissions. The test that I'm
>failing is the Idle Hydrocarbon test.
>  .
>  .
>  .
>Result: still fails, but not as badly. I even went to the
>extreme of putting 87 octane gas in it for the test. I am
>thinking of trying the oxygen sensor but am given to
>understand that it primarily affects CO -- which I pass --
>not HC (insights welcome...especially a part number of a
>compatible, non-Bosch, one-wire O-sensor) I may have misset
>the timing when I tested it this morning -- so that needs to
>be re-checked.

Eric, the three most important items affecting emissions are:  timing,
mixture, and O2 sensor.  Make absolutely sure that your ignition timing is
set to spec.  Retarding the timing causes incomplete combustion, and
results in unburned fuel being pumped into the exhaust--in other words,
high HC emissions.  I believe your car has the single-mode throttle switch,
so the injection system is in closed-loop mode at idle.  That makes your O2
sensor very important.  Check it and replace it if necessary.  You can get
a $20 substitute by asking your parts man for the cheapest single-wire
sensor he has for an L-Jetronic VW Rabbit or Golf.  You will simply have to
solder you own wire on.  Last, the mixture on these L-Jetronic cars is
adjustable.  Make sure yours is set properly.  You can adjust the mixture
by turning the bypass screw on the air flow meter in or out.  In is richer,
out is leaner.

With the O2 sensor disconnected and the timing set correctly, you should be
able to adjust the mixture for a nice, smooth idle.  Adjust for maximum
idle RPM, and then turn the bypass screw out (lean) a bit, just enough that
the idle is still smooth and stable.  You should notice some degree of RPM
drop.  Reconnect the O2 sensor--you should notice little to no change in
the way the engine is idling.  If there is a big change, either the O2
sensor is bad, the timing is set incorrectly (retarded), or you have some
kind of mechanical failure, like an unseated exhaust valve.

After using this same technique on my '82, it passed CO emissions without
any trouble at all, starts easily, and runs smooth as silk.

Oh, one last, but less likely possibility is that one or more of your
injectors is horribly dirty.  An injector can get so gummy and dirty that
its spray pattern looks like a squit bottle on "stream" rather than
"spray".  That can cause an engine to run poorly and also increase HC
emissions.  I haven't actually seen this happen, but it is possible. 
Dumping a can of BG 44K into the tank cures the problem, along with
cleaning up the intake valves.  I recommend dumping a can into your tank
regardless.  It's expensive (about $20 per can) but can cure a lot of ills.

Rich
Montrose, CO
'82 GTV6 Balocco

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