RESUME: 100Q engine problems

SJ syljay at
Tue Dec 21 23:21:53 EST 2004

From: "Denis J" <sparkplugvw at>
Subject: RESUME: 100Q engine problems

> I m not home and i sent that today but it seems it did not get to
Audifans!! quattro at,, i dont see my my posts !!!!
****I dont see a Cc: or audi address in your email. Are you sure you sent it
to quattro?
> Car: Audi 100Q 1989
> Engine: 2.3 NA CSI-3
> symptoms:
> - Hard starting hot and cold, starting as a big lazy cow.
**** Nobody knows how a lazy cow starts . . .better to keep comments like
that out since it does not add anything to clarify the problem.
What are the symptoms? Long cranking times? Does it try to start on one or
two cylinders and then dies? Does it cough and sputter?
Did you check for a binding sensor plate in the fuel distributor?
Are the plugs wet?

> - Lower power; cant pass other car on the road. If i push the accelerator
more than the half the engine slow down instead of accelerate. I must let
the engine take breath before push more on the accelerator. The sparkplugs
look white and gray since the engine is going bad.
**** White and grey? That sounds like a lean mixture.

> -Bad fuel economy
> -The piston swim in fuel if i miss the first start on cold weather.
**** That means that the cold start valve is working. Maybe its always on?
You would be running rich all the time, lousy mileage and hard starting.

> -Now the car is stalled 350km form home at -25C
> I did:
> -Installed a check engine light:Very useful.
> -I Retrivied the fault codes: knock sensor only ; cleaned the sensor
connector, was oxidated.
> -Reset the fault code and check for others . None since i fixed the knock
> -Did output check with the check engine light;everythings ok.
> -I changed the DPR connector and cleaned it, since that day the car ran
powerful and good fuel economy for 2 weeks,,,, then back to a big lazy
**** Car should run with DPR disconnected. This is the limp home mode.
Starting may be difficult with DPR disconnected.

> -The fuel pump is 1 years old, i did not check the delivery rate.
(Pressure dropped to 4.3.)I took the fuel pump from my ex-5000TQ 87 and was
running very good before i removed. I should have took all the inject system
from that car :-(.
> -Checked the fuel filter on the fuel pump;ok
> -Checked fuel lines:ok;They all been changed last summer 2004.
> -Changed fuel filter close to the fuel distributor.
> -Checked fuel system pressure;4.5 bar and 67 psi with another meter.
System pressure drop immediately to 20psi when the engine stop. The pressure
then drop slowly to 5 psi and stay there for maybe 1/2 hour.
**** Stay with PSI standards, Americans arent familiar with "bar" readings.
You defnitely have a problem in this area. System pressure should be 90 PSI.
And, it should not drop off so quickly. You should have minimum 40 PSI after
10 minutes.
Low pressure is either fuel pump or pressure regulator.
Pressure drop off is either fuel pump check valve or pressure regulator.
Cold start valve could be leaking.

> -Just changed sparkplugs
> -Try other sparkplugs wires;Beru. Checked on the dark if i can see any
sparks come out the wires and distr. cap.
> -Checked the vacuum: 9psi. suppose to be around 20. The only leak i found
is one injector insert.
**** Whats this? What vacuum? Vacuum when engine is running?
Is this what you mean by a vacuum leak? Extra air coming into the engine
thru a broken hose?
How are you testing for this? Vacuum readings are in inches nor PSI.

> -I removed all the injectors and clean around, put silicon around them and
putted them back. The stores were closed that time, it s why i did that.
> -Removed the DPR and cleaned it.
> -Just changed oil :castrol synthec 5W30. Cause the car was swimming is
fuel;after lot of starts and wet cylinders
> -Checked the current on the DPR. Bentley procedure.:ok.
> -Checked the ISV with 12v charger:ok. But when i plug the wires to the ISV
the 12 V drop to 0volts
***** Huh?
You test the ISV with a 9 volt battery.
Explain about the 12 volts dropping to zero. What 12 volts? What are you

> Note: The engine seems to start when someone start while i push the distr
plate with my hand !!!!
**** I mentioned before about a sticking sensor plate. Make sure its clean
and free to move.
Push or pull?
Are you trying to start the car with the air bonnet off?

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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