-----Original Message-----
From: Navarrette, Vance
Sent: May 11, 2005 11:50 AM
To: 'Lizirbydavis@cs.com'; 6pack@autox.team.net
Subject: RE: running on "dieseling"
Joe:
Running on is common on carbureted cars of that era. Emissions
laws effectively required lean fuel mixtures at idle, which are prone to
running on. Nothing is harmed, although it sounds terrible and is
annoying. You can try fattening up the mixture, but that will probably
hit your fuel economy, and may make black smoke. You probably need a
needle that is richer at idle but the same everywhere else to really
deal with it in this manner.
Not to worry, the TR6 has a solution already installed, although
in our cars it is frequently disconnected or broken. It is the
anti-runon valve, located just below the carbon canister. It is often
removed by people under the erroneous impression that removing the
emissions equipment will improve performance or mileage.
If your valve is intact, the most likely culprit for it failing
to work is the that the wiring at the oil pressure switch is
disconnected or improperly connected. There are 3 wires, and 6 possible
ways to connect the wires. Only 1 way makes the oil pressure light, the
run-on valve and your alternator light work properly. Depending on the
way the switch is wired, your oil pressure light may stay on, come on at
the wrong time, etc.
Make sure everything thing is in place, and connected first.
Check the connections at the valve and the oil switch for corrosion,
etc. Test the valve by applying 12v directly to the terminals. You
should hear a loud click. If everything checks out, then your oil switch
is wired incorrectly. Note that you CANNOT test the switch itself with a
volt ohm meter, as the anti-run on function only operates when oil
pressure is applied and the ignition is in the off position. This will
only occur for a few seconds after your turn off the motor (i.e. when it
will try to run on). The only way I know to test the switch itself is to
have a buddy start the car, wait for the oil pressure, and then switch
it off while you watch your voltmeter. You may need to do this several
times.
The correct wiring diagram will be in your owners manual. The
drawing of the switch shows 3 terminals oriented the same way as the
switch has them oriented. Attach the wires the same way as the drawing,
and you should be in business.
Vance
-----Original Message-----
From: owner-6pack@autox.team.net [mailto:owner-6pack@autox.team.net] On
Behalf Of Lizirbydavis@cs.com
Sent: May 11, 2005 11:18 AM
To: 6pack@autox.team.net
Subject: running on "dieseling"
What causes my car to run on for a few seconds after I shut it off?
I've been fiddling with my timing trying to optimize performance. I
idle at about 1000rpms hot. Compression is 9.7:1 Is this dangerous?
Joe Davis
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