4kq hard starting-stumbling

[Ben Swann]

Check the fuel injection thermo sending unit located on the cooling neck.
make sure wiring is good and connection is good.

The Negative temp. coeficient(NTC) sensor should be around 2500 ohm at
20degC(68F) higher resistance at lower temp and lower resistance with car
warming up.

Ben

[Date: Wed, 22 Jun 2005 14:13:47 -0700 (PDT)
From: William Perron <w_perron at yahoo.com>
Subject: 4kq hard starting-stumbling
To: quattro at audifans.com
Message-ID: <20050622211347.13577.qmail at web33405.mail.mud.yahoo.com>
Content-Type: text/plain; charset=iso-8859-1

I've been having a problem w/ my '85 4kq lately that I
can't seem to figure out.

Problem:  Hard starting when "cold"-- cold varying from 50F to 95F.  Car
will sometimes catch when key is first turned, but then stalls.  After a few
attempts the car will eventually start, but will have trouble
idling for about 30 seconds- usually need to keep the  revs above 1500RPM
during this time - then the idle evens out and I can drive away.  Once car
is warm, I can turn off and restart easily.  AFter it sits for a few hours,
the hard starting begins again.

Diagnostics/Changes so far:
-Checked Idle switch- it is working properly
-Swapped ECU temp sensor with known good--no change
-Cleaned all grounds, connections including intake manifold grounds for ECU
-Swapped in known good plugs/wires distributor cap - no change
-Swapped large intake manifold boot - no change
-Attached hose clamps to all ISV hoses - no change
-Swapped ISVs - no change
-Checked all hoses for vacuum leaks - nothing found
-Re-did all small vacuum hoses in engine compartment w/ new ones- no change
- Installed new injector seals - no change
-Centered air plate in fuel dist. - no change
-Checked that Cold start valve is receiving voltage hen cranking - it does
receive voltage
-Checked after start enrichment function--ECU does nrich mixture after
starting
-adjusted idle speed (w/ duty cycle meter), mixture nd timing- no change
- installed known good fuel pump relay no change
-installed a normal relay so fuel pump runs whenever
ignition is on--waited at least 30 sec to "prime
system" ---no change

I'm really not sure what else to check at this point.  ONe interesting thing
I noticed is that the car seems
to start pretty well if I leave the ISV unplugged??  I hough the ISV might
be a problem so I swapped in a
differnt one--no change...

Any thoughts or comments appreciated


-Bill
Burlington CT
'85 4kq]