Cold start issues continue (84 4000 quattro)

[Ben Swann]

OK - now you are getting somewhere.  As I suggested, rule out the obvious and work
toward the harder to identify weirdness.  You had a vacuum leak that was throwing things
off and probably causing the majority of problem with starting and driveability.  So
what can be wrong now?

I'll take another SWAG.

Did the P.O. change the mixture setting to compensate for the air leak?  I wouldn't be
surprised.  You can adjust CO/mixture by using  3mm hex/allen key if that is the
problem, but know where you started - how many turns.  Clockwise to enrich.  Best to
leave alone if you don't know for sure what you are doing with this.

Is the throttle body switch operating correctly?  Use VOM to test the idle switch
operation at the connector.  These go bad - common problem.  If switch is not closing
properly, then a variety of things won't work right - closed loop operation at idle,
Idle stabilization and even no start condition.  Kind of a pain to fix, since it
requires to remove the throttle and the switches aren't that common.  I'll lay odds that
this is now the no. 1 problem (with your engine that is).

If you have CIS-e then you have a differential pressure regulator, not a WarmUpReg.
These do get dirty, clogged and so a careful cleaning may be in order.  You want  DPR
repair kit on hand - basically to replace the O-Rings - dealer item..  I have
experienced the DPR causing a no start hard running condition, and is most common when
the car had been sitting for awhile.

By the way, have you completely purged the old fuel and replaced with fresh?

Since the car is a recent acquisition, you should have already replaced the Air Filter
and thouroughly cleaned the CIS metering plate and assembly and checked for binding.   A
lot of bad things are often revealed during this routine but oft. Neglected maintenance.
Fortunately, they are easy repairs involving cleaning and rubber hose replacement.

There are a lot of other things, but these are what I'd look at next.  See:
http://www.gtquattro.com/FAQ.html for other common DIY fixes.

Ben

[Date: Wed, 11 Aug 2010 06:06:35 -0700
From: Johnny B <pre95 at live.com>
Subject: Cold start issues continue (84 4000 quattro)
To: <quattro at audifans.com>
Message-ID: <BLU142-W236C2BE72A2FB475FB7179C8960 at phx.gbl>
Content-Type: text/plain; charset="iso-8859-1"


Well thus far no luck. I have scoured the engine compartment for vac leaks, fixed one
which corrected my high idle, but still have my cold start issue. The coolant
temperature switch came in yesterday (that mounts between cylinders #1 and #2 on the
bottom of the coolant neck leading in to the head), I installed it and this morning,
still a bad cold start. 

Once the car is started, my idle is rock solid, does not wonder, and I have good power
up to ~5k which seems fine for a JT. No running condition issues once started. I did
notice this morning when it first started, I touched the gas pedal to bring the R's up
and it simply died. I restarted and let it idle for ~30 seconds and all apparent running
conditions went away. 

Someone had mentioned the fuel pressure regulator could be at fault, specifically the
"warm up regulator on the fuel head" which I am uncertain as to what he means. There are
2 "fuel regulator" pieces near the fuel distributor, the vacuum regulated piece mounted
towards the front of the car in front of the fuel distributor, and the FPR mounted
directly to the fuel distributor that has 2 wires leading to it. 

Any insight greatly appreciated, I know I have said it but it's very annoying having a
car that is otherwise well sorted and good running with a bad cold start. 

Johnny]