Re. Narrowing down my start issue (84 4kq)

[Ben Swann]

So far this coincides with what I suggested in the prior emails.
 
Leaks in the carbon canister lines can indeed be problematic.  Any Air leak will result
in harder starting and initial running and the larger the leak the worse the problem.
 
Engine going into closed loop operation when warmed up making things run better are
indicative that it can now compensate better for an air leak.  When engine warms up and
goes closed loop operation the Oxy Sensor, temp sender signal ECU to adjust fuel mixture
via DPR and fuel frequency valve.
 
If idle switch is INOP then there will be no CS pulse!
 
Funny I never used anything fancy to adjust the airflow plate, but certainly nothing
like doing it precisely.  Basically you don't want any binding either due to bad
adjustment or grit.
 
Don't get carried away with the fance tools and procedures on this engine.  It really is
far too simple!  Just change air filter, dig in and clean up the mess that is in the air
flow metering area.  Spray clean it, work it, lubricate, reassemble.  Then drive the
pejesus out of it.
 
You are very near solving this.
 
Ben


  _____  

From: Johnny B [mailto:pre95 at live.com] 
Sent: Monday, August 16, 2010 3:02 PM
To: cody at 5000tq.com
Cc: benswann at verizon.net; quattro at audifans.com
Subject: RE: Re. Narrowing down my start issue (84 4kq)


Spoke with the previous owner of the car this morning regarding my hunt on this starting
issue. 

Apparently the fuel pressures were checked several times over, as well as each injector
being tested for proper spray & pressure, all seemed fine. He noted spending over $600
over the course of the past 2 years replacing everything he can touch along the way.
Fuel pump / check valve were replaced as well (so not stock units as I had previously
thought). He had the DPR tested and tuned, fuel pressures checked, new fuel pump &
filter put in, ECU coolant temp sensor replaced, all vac lines replaced (before I did it
all over again), ISV tested and cleaned, as well as a vac leak down check on the system.
Apparently all of this checked out while he was on the hunt for this problem (probably
why it runs so sweet once started!). 

I am still going to swap DPR's to see what she do. I am also meeting up with a friend
today to toss on the metering plate adjustment harness so I can dial it in properly
apposed to playing the guessing game. The DPR installed does respond when unplugged
(idle drops roughly 200rpm), plugging it back in at idle will result in an increase of
idle by 200rpm. One portion of the vac system I havent checked is the charcoal canister,
which will be getting a thorough once over today (though I dont believe the canister can
cause this start issue). Accumulator checks out, and has no leaks. 

Correct me if Im wrong, but because this is happening at start up, and at no other time
with the car, I am ruling out the ECU and sensors related to the ECU as when first
starting the car reverts to the static adjustment at the fuel metering plate as to how
it should run. After 5-10 seconds when warm the sensors will tell the ECU to switch over
to closed loop mode, when cold it takes a bit longer as the sensors are not reading
anything yet (everything is still too cold). The PO stated he has started the car with
the ECU out when hunting things down on the start issue, he was surprised it fired up
then quickly realized it was because the ECU controls nothing while the idle / wot
switch is engaged. 

Not throwing in the towel, though it's definitely trying my patience. At least I will
know everything I need to about CIS-E when this is all over! (HUGE thanks to everyone on
the mailing list here!! 

Johnny



> From: cody at 5000tq.com
> Subject: Re: Re. Narrowing down my start issue (84 4kq)
> Date: Sun, 15 Aug 2010 19:52:06 -0400
> To: pre95 at live.com
> CC: benswann at verizon.net; quattro at audifans.com
> 
> Check. The. Fuel. Pressures.
> 
> -Cody (mobile)
> 
> On Aug 15, 2010, at 4:22 PM, Johnny B <pre95 at live.com> wrote:
> 
> > 
> > Well thanks for the great tip! I swapped the fuel pump relay for the fan relay from
my ur-quattro and no change on start (though the fuel pump runs on a constant as you
said it would, I let it run 3-4 seconds before trying to start, same symptoms. I put the
fuel pump relay back in Huw!). Very frustrating to say the least... I'm, not really sure
where to go from here regarding this start issue. If its not a lack of residual fuel
pressure, and not a vacuum leak (just replaced all formed vacuum tubes & all cloth
covered vac lines, checked the entire system over), and knowing it had this same issue
prior to new injectors being installed (this problem carried over from before the engine
rebuild, which included all gaskets, rings, cylinder head rebuild, and fuel injectors +
seals).. where do I go from here? 
> > 
> > Starting to get discouraged... if you give it any throttle over a light touch of the
gas pedal for the first minute (when cold) it bogs and wants to die. Does the same when
hot but only for the first 8-10 seconds... Im thoroughly stumped. Car has great power
through the RPM band, top & low end are fine, idle is always rock solid just shy of 1k,
cannot source any vac leaks with the chemtool when warm or cold... not really sure what
else to check. Once the start symptoms pass, the car is perfect.. it doesnt drive like
it has any issues at all which just adds to my frustrations. 
> > 
> > Thanks guys, I'm not giving up hope but definitely understand why so many throw in
the towel and go EFI. 
> > 
> > Johnny
> > 
> > 
> >