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[St] Still have cold start problem



A will back I made the post below. Basically I was having to give the
bike a bunch of throttle to get it started and then it would not idle
until it was warmed up. Once warmed up the bike runs fine. I removed
the stepper motor and the plunger was a bit dirty so I cleaned it and
put everything back together. This did not really help with the
problem.

So I assume either the stepper motor is dead or one of the three
sensors mentioned below is. I know the coolant temperature sensor is
OK as the gauge works. I assume that if either of the intake air
temperature and pressure sensors were bad the bike would not run well
once warmed up and/or the MIL light would be on. This is a 1999 ST
with 49,000 miles on it.

I am tempted to just buy a new stepper motor. Can anyone offer any insight?
Rupert

---------- Forwarded message ----------
From: Rupert Galea <rgalea@xxxxxxxxx>
Date: Wed, Oct 31, 2007 at 7:54 PM
Subject: Re: [St] Cold start circuit is no longer
To: ST@xxxxxxxxxxxxxx

 Found this in Haynes
 "Cold starting is controlled by the ECM which reacts to information
 sent by the intake air temperature and pressure sensors, and the
 coolant temperature sensor, and adjusts the fuel requirements
 accordingly - there is no manual method (i.e. choke) for assisting
 cold starting"

 Since the bike runs fine once warmed up and there is no MIL I am
 guessing these are fine.

 Also from Haynes
 "The idle air control valve is actuated by the ECM and set according
 to information received by the ECM from the various sensors. The valve
 is used to control the engine idle speed, to adjust the air supply on
 engine overrun, to correct for altitude, and for cold starting. The
 idle speed cannot be adjusted manually."

 So it looks like I have a gummed up stepper motor.

 Thank everyone
 Rupert
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