Re: Nasty Idle Question

[Dan Bubb <jdbubb@ix.netcom.com>]

Could be either the auxilary air regulator or the control pressure
regulator. The air regulator, in my experience, just seems to get gummed
up and cleaning it and checking it's little heater resistance seems to
do the trick. As far as the control pressure regulator, I've never been
able to make one of these work right once it's screwed up. They seem to
fail in a mode that is fine for warm running, but doesn't lower the
control pressure to richen the mixture when the engine is cold. A way to
test this is to stick a 3mm allen wrench in the mixture adjustment screw
and put a little rotational force on it without actually rotating the
screw. this gives enough friction to allow you to pull the metering
plate up a little. If the idle improves to a normal level as you pull
the plate up when the engine is cold it's probably the control pressure
regulator.
Dan

Colin wrote:
> The problem:
> 
>      When it first starts on a relatively warm day, it idles like a 20 year old
> Ford.  After it warms up for a few minutes, it smooths out and is good.  On
> cooler days (like we've been seeing up here recently) it starts not bad, but
> the idle goes lousy again after a couple minutes until the engine gets up
> towards normal operating temperature.  Yes I put the O2 sensor in, and it's
> fairly new.  Can't find any intermittent vacuum leaks and the header and
> manifold are snug with good gaskets.
> 
>      My question is...is the lousy idle when cold something I have to live
> with, or can I smooth it out, even a little?  I expected it to roughen out a
> bit with the head and exhaust, but it's really severe.  The idle bobs between
> less than 100 and about 500 (it could be worse, I've got the warm, smooth idle
> at 1100).  I think it should be something I can resolve, but I'm out of ideas
> on what to poke at next.  Maybe the fuel pump?  I replaced the filter about 2
> months ago and that didn't help.
> 
>      There's more about the car (you don't want to know how much I hate
> balljoints...) including suspension and such, but that doesn't really apply to
> the question at hand.  Thanks for any responses.
> 
> Cheers,
> Colin
> 
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