type44T cold start problems

[SJ]

>From: JordanVw at aol.com
>Subject: type44T cold start problems..

>im having probs w/ the '86 5kt again....same problem as before..  car
starts,
>then idles like crap, really low..  shut it off, start up again, idles
fine,
>then drops down low again after one minute..
>the idle switch on the throttle body was replaced.. as well as both temp
>switches..   worked fine for a few months, now its doing the same thing
again...
>ideas?
***** Sounds like a lean mixture.
Car starts ok, because the cold start valve gives added fuel.
When cold start valve shuts off (based on temp sensor input), EFI is using a
lean mix and engine stumbles and barely runs.

Do the propane test to verify. Add propane at air intake input and see if
that clears up the stumble at idle.
If problem clears up, you have a lean mix.

Lean mix can result from not enough fuel or too much air.
With these cars, the problem is almost always too much air - - air leaks.
Use propane to find the air leaks. Especially at the fuel injector insert
seals. Are these original injectors and inserts and O-rings?

Lean mix can result from insufficient fuel pressure >> bad fuel pressure
regulator.
Test the fuel pressure - I use a home made fuel pressure tester. Contact me
off line and I'll send you pix and build instructions.

Lean mix can result from bad temp sensors. They tell the EFI system that its
warm when its cold and DPR does not provide sufficient fuel flow.
You can take off the sensor connector and substitute with a resistor. Pick
the right one from the list below.
Temp vs Resistance readings on my 90 100q temp sender.
deg F   ohms
35        4500
60        3200
80        2300
100      1360
150      510
207      203

Lean mix can result from bad computer. You are in Limp Home mode.
You can simulate this by removing connector from DPR. See if the symptoms
are same.
Car will run in Limp Home mode with a warmed up engine. .. but it may not
start.

You can have a combination of problems. I had a similar problem as yours.
Fuel Injectors were old - 1988 and 165k miles ---> plugged up ---> too
little fuel --->lean mix at idle (O2 sensor out, open loop mode)
Fuel Injector O-rings leaking ---> additional air --> lean mix
Not enough fuel and too much air gives you a real LEAN mix.

SJ
85 Dodge PU, D-250, 318, auto
85 Audi 4k - - sold but still on the road
88 Audi 5kq
90 Audi 100q




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