Date: Wed, 09 Sep 1998 23:02:28 GMT
From: Ywan Mason <ymasonnopsamsouth.net>
Subject: Re: Help - fast idle on '87 9000 Turbo
Try
http://www.townsendimports.com/tuneup_folder/adj_basic_idle_lh2.1.html
for setting the base idle. This is a revised edition of the TSN FAQ.
More than likely the problem with the cold start hunting is an air mass
meter. No checks on it will conclusively pin point its trouble. Before
you condemn it though, you have to make sure every other base is
covered. This includes making sure all tune up parts are current and
good. All have a maximum recommended service limit of 30K miles. They
include the fuel filter, air filter, plugs, distributor cap and rotor.
You should remove the throttle housing bellows and clean around the
plate while holding it open with carb cleaner and a toothbrush. Remove
the AIC valve and clean its shutter wheel as well. Deposits here can
cause the wheel to bind and burn out the valve's motor. Make sure there
are no vacuum leaks, check all the vacuum lines to the intake and make
sure each one holds vacuum. If not, trace out the leak and remedy it.
Then see http://www.townsendimports.com/tuneup_folder/amm.htm The cold
start hunting/stalling problems are best repaired by a process of
elimination.
There is the possibility that multiple problems are contributing to the
problem. The high idle could be caused by the AIC valve being dirty and
binding or burnt out from long time binding. The electrical connections
at the valve, throttle switch, or air mass meter could be corroded or
loose. The grounds at the intake for the LH system could suffer in the
same way. Never overlook fuel pressure when diagnosing a running
problem. Test it for volume, operating pressure, high limit pressure and
rest pressure. Make sure the ignition timing is set correctly.
Good Luck
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