Audi 80 ADA weak mixture

[murphyv310]

I have already put on a post regarding my car being hesitant when cold.
I think now though the problem is a weak mixture I have replaced the lambda probe and fuel filter. I have checked the plugs and they appear very whiteish, I have also checked the ignition timing, I use good fuel and have used injector cleaner twice in the last month.
One strange thing is if you dip the clutch at say 60 mph and switch off the engine and then restart the car goes great for a few minutes then the fault comes back, any ideas?
Trevor

[mikes2]

I would suggest looking at fault codes or using VAG Com to check the temperature sensor output with the engine running.

It's possible the temp sender to the ecu is sending an always warm
value so not enough fuel is sent.

[murphyv310]

Hello Mikes2 would you know the cold & hot resistance values of the temp sensor?
Thanks in advance.
Trevor

[mikes2]

At room temperature it should be around 2000 ohms.

As it heats up, the resistance drops

[murphyv310]

Hi Mikes2 Thanks for the reply. Mine is 2.7kohm when cold, dropping to 10 ohms at 90 degrees, I would think thats ok.
I will try to read off the codes though but am unsure as how its done or perhaps I am stuck with a VAG dealer. Do you know if there is a manual covering the ADA engine.
Trevor

[mikes2]

Sounds about right if slightly high when cold, although it would be good to see the temperature reading in VAG Com.

For a manual you may be able to get one from here:

http://erwin.audi.de

[murphyv310]

Hi.
I have replaced the temp sensor to no avail, but I have seen on another thread that the ECU relay may have dry joints, there is no ECU relay in the fuse box, and I wonder if the car has this relay, If it does is it behind the speedo? Its an ADA.
Trevor

[mikes2]

the ecu relay only applies to the ABK digifant cars

[murphyv310]

**** CURED ****
I Was having a fiddle at the various plugs and sockets when I noticed the plug for the Knock sensor seemed to have a raised portion under the rubber boot, I took the plug out and the connector was not protruding as it should be in fact the electrical plug had come undone from its housing. I took the car for a run and the fault is gone. I wonder if the Knock sensor is out of circuit when the car is cold? Also do you think the ECU needs re-set or will it learn the problem is fixed, I also notice the engine is running about 5 degress colder which makes me think the ignition retards if the ECU cannot "see" the knock sensor.
Trevor

[mikes2]

The ecu uses a default value if the sensor gives no signal back to the ecu after startup.

There should be no need to reset the ecu