Jay, I can't tell you for sure that this is what is happening, but: I think
that what you might have happening is that the block and and internals are
getting warm, while the air outside is still cold. As you know, a cold
engine requires more fuel to start and run than does a warm engine. If you
have a warm engine, and the PCM sees a cold air temp(IAT sensor) and a
cool/cold coolant temp(Coolant Temp sensor), the PCM won't know the engine
internals are warm. Therefore, when you crank it up, the PCM immediately
throws more fuel into the mix(kind of like a "choke" function) because of
the "cold start" condition it's seeing from the sensor input it has. The
engine internals are warm and do not require as much fuel to run properly
and are being fed too much fuel. When the engine stumbles or misses because
of an overfuel condition, the PCM picks up on it and backs the fuel off
accordingly. What you could do to correct or help this condition is to
acquire on of Bernd's IAT adjusters. You could then: turn the key on and let
the PCM take a second or two to analyze the sensors and you could use the
IAT adjuster to make the PCM see an IAT input that is higher than the
corresponding outside ambient temp. So say it is 10* outside when this
conditon occurs one day. The next day, try adjusting your IAT adjuster up to
30* or so and see how it affects it. If it makes the condition better, but
doesn't cure it, continue moving up the temp scale on the adjuster the next
morning. If you get to a point where the truck takes longer to start or
won't start, you've gone too far and you need to come back some.It wouldn't
take you long to figure out how to adjust it according to the outside temp.
HTH,
Will Coughlin willcoughlin@hotmail.com
'00 Reg. cab 2wd, 4.7L/NV3500HD/9.25" 3.92 sure-grip
----Original Message Follows----
From: "jay & dana" <jay&dana@telus.net>
Subject: DML: Block Heater question
Date: Thu, 13 Dec 2001 16:20:54 -0800
For those of you that live in colder climates and use a block heater, I
wonder if I can ask you a question. On the mornings when I don't use my
block heater the truck starts and fast idles fine. But some times I will
put my block heater on a timer to start 2 hours before I go to work in the
morning. When I do this the truck starts fine but will spit and sputter for
aprox. 2 seconds, then run fine. I'm just wondering why the block heater
being plugged in would make the engine sputter like this for a very short
time, while without the block heater there is no hesitations. (and don't say
"then don't use the block heater") :-) This has happened like this for a
few years now in winter and has just got me curious. BTW, this is on a 97,
318 and it's getting cold here in BC, Canada. Thanks for any responses,
Jay
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