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From: junk@ur-tut.UUCP (Jan Vandenbrande)
Newsgroups: net.auto.tech
Subject: Re: still shaking when cold
Message-ID: <347@ur-tut.UUCP>
Date: Tue, 4-Feb-86 13:38:23 EST
Article-I.D.: ur-tut.347
Posted: Tue Feb  4 13:38:23 1986
Date-Received: Fri, 7-Feb-86 22:06:12 EST
References: <265@uwstat.UUCP> <197@xios.UUCP>
Reply-To: junk@ur-tut.UUCP (Jan Vandenbrande)
Organization: Univ. of Rochester Computing Center
Lines: 55
Keywords: Rough Idling Problems, etc. plugs


Alot of you out there seem to have some problems related to rough idling
with a cold engine. I have had a similar problem recently and was able
to fix it. Try the following:

1] Look at the vacuum hoses. See if they are attached well, look for
cracks. If you are capable, check also the valves (if any) and vacuum
activated switches (if any) in the vacuum lines. Don't forget the brake
booster. Mine (and many cars') works on the vacuum. A leak in that may
cause you lots of headaches [check vacuum booster => pedal should go down 
when starting the car, car should not stall when depressing the brake violently)
Keep in mind that some of the vacuum hoses may come loose and start "leaking" 
when warm. So check these hoses with hot and cold engine.
Vacuum hoses control all kinds of functions: vacuum advance/retard, regulating
air/fuel mixture, the choke, etc. So it is not unlikely that a vacuum leak
may have all kinds of consequences. Look at the spark plugs. When thy are
sooty, your air fuel mixture might be too rich, or you ignition is off.
Check also the gaskets between intake manifold & carb./fuel injector.
Leaks there might do nasty things too, but these are not that common.
There is no sence adjusting your timing/carb. when you have a vacuum leak.
Your car is not going to run right. For those of you with some more equipment
try using a vacuum gauge.

2] Check the electrical system for bad contacts. Get a Volt-Ohm meter, the
circuit plan for your car, and check whether all the apropriate places get
juice, and if it is the right amount. Nowadays more and more things are
activated electronically, so a bad contact, or a bad sensor will ruin
it all in rather misterious ways. My problem with rough idling ended
up being a corroded connector that controlled parts of my choke and
the intake manifold preheat. Nothing a bit of sandpaper can't fix (to
clean of the contacts) but it did take me a while to find it.
This is all under the assumption that your battery, spark-plugs, coil
(test with VOM), points/Hall sender, idle stabiliser (if any), injection
computer (if any), fuses, relays, etc. are all functioning properly.
Don't be surprised to find contacts that work part time only. So when
you check your contacts, wiggle the wires to see what happens.

3] Maybe your injectors/carb. registers are soiled. This is more delicate.
If you car runs well when warm, I wouldn't worry about it.

4] Pollution Control Stuff. I know very little about this area, but I do
know that this may ruin your day too.

5] Check for H2O in your gasline/tank. Disconnect the gasoline tube
early in some cold morning and let some of it gush into a container. Let 
it settle. If you find junk, complain to your favorite gas station, or check
your gastank for leaks, rust, condensation water,... 
Be carefull though when you do the above operation. Gasoline tends to be
flamable.   

This is about all I can think of, off hand. Try this first and see if it does
any good. If it doesn't try net.auto.tech to see if anyone else has some
peculiar experiences with this type of problems.

Jan.