4kq hard start when cold (vacuum leak?)

[Tom B]

Thanks for the tip Russ. I will check the temp sensor on friday, which is
the soonest I will get a chance. I had noticed in my Bentley that that was
one of the things that can cause this kind of problem, but had discounted it
because before when I had had this prob it was a broken vacuum line. Oh
well, might as well check it also :-)
Thanks and have a good one,
tom


>Tom,
>In addition to the vacuum lines, you may also want to check the
>resistance of the coolant temperature sensor, the two-prong plug-in on
>the bottom side of the upper radiator hose mount on the cylinder head.
>It should be 2.5K ohms at 60 degrees F according to Bentley, IIRC. If
>you're in colder climes (it was 68 here in Milwaukee today!), I
>checked the resistance on my working sensor for a friend recently at
>36F and came up with 5570 ohms.
>
>Lower resistance fools the engine into thinking the engine is warmer
>than it actually is, so it leans out the fuel mixture. Your engine
>runs great for a couple seconds because the thermo-time switch is
>dumping fuel into the intake manifold to facilitate starting. The car
>dies when that extra fuel supply switches off. When you step on the
>gas to deliver more fuel, you're actually contributing more air
>through the throttle plate than fuel through the injectors, so the car
>stalls out.
>
>Hope this helps,
>Russ Maki
>Ixonia, Wis.
>
>
>
>
> > From: "Tom B" <dr_hydro at hotmail.com>
> > To: quattro at audifans.com
> > Subject: 4kq hard start when cold (vacuum leak?)
> > Date: Wed, 05 Dec 2001 15:31:51 +0000
> >
> > Howdy all,
> > My '87 4kq has developed an interesting failure mode. When cold
>starting the
> > car will start, run fine for 2-4 seconds, than die. Giving the car
>gas
> > causes it to die even quicker. After about 15 starts you can get the
>car to
> > stay running if you keep the engine revved to about 3k+.  After a
>minute the
> > car will run fine, with no problems.
> >
> > I had the exact same problem on an 82 cgt 10 years ago, and, too
>make a long
> > story very short, ended up finding out that the problem was a broken
>vacuum
> > line (ask me my opinion about Imported Car Center in Williston Vt :-
>( ).
> > When the line was fixed, the car started and ran great.
>Unfortunately I did
> > not do the repair myself, so I do not know which line was
>broken/leaking.
> >
> > Would anyone happen to know just which line it may be? I am planning
>on
> > replacing all of the vacuum lines this weekend, but would like to
>replace
> > the one that is causing this immediately.
> >
> > Thanks in advance,
> > Tom
>
>


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