XPost: alt.home.repair
From: kludge@panix.com
Ken Blake wrote:
>I have a Mitsubishi Lancer 2003 which has low idle speed.
>So low that it stalls unless I keep the gas on the peddle.
>
>What causes that?
You're thinking backwards. Think about what happens when you're at idle.
Something needs to happen to make the mixture more rich, and that could be
done in all kinds of different ways. Some cars have an extra injector just
for idle, some have software in the ECU that runs the normal injectors more
rich, some have a gadget in the carb that is activated by engine vacuum.
I have never worked on a Lancer, but less than a minute with Alldata shows
me that you have an idle control valve. Check it and make sure it is
functioning properly. Is it getting a control signal from the computer
to open and close? The meter will tell you. Is it actually opening and
closing? Your finger blocking the entrance will tell you.
Plenty of other things can cause the mixture to get messed up at idle and
that includes vacuum leaks, so if the valve is operating properly checking
out the vacuum lines is your next step.
If you use a crappy scanner that just gives you codes, you will see a bunch
of codes saying the mixture is wrong, but you already know that. You don't
need the scanner to tell you.
If you use a proper mechanic's scanner you can see all the inputs coming into
the ECU, which includes the mass air flow sensor, and you can see if those
inputs are good and whether or not the ECU is opening and closing the valve
properly. This is useful information but the most important information
comes from your eyes and ears.
>And more important, how can I adjust it?
You do not, you fix it.
>Where do I get more information specific to the vehicle?
Alldata will get you a manual if you don't have one, but for this car
even a Haynes will probably tell you what you want.
--scott
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