The UK quattro Network - Audi Type 44 Service Manual
The UK quattro Network
Type 44 Exhaust and idling tests (Petrol engines)
Visual check
Before checking or adjusting it is necessary to ensure that all parts which influence the exhaust such as:
- Vacuum pipes
- Crankcase ventilation
- Air cleaner
- Catalyst
- Lambda probe
- Restricted filler neck
are fitted/connected and that the system is free of leaks.
Check and if necessary adjust idling speed and CO content
- For test and setting conditions, values and spark plugs, see "Emission and idling test" binder.
To avoid injuries to persons and/or damage to the ignition and injection systems the following must be noted:
- Disconnect and connect ignition system wiring - including HT and tester wiring - only with the ignition switched off
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Work sequences according to engine code letters:
After making adjustments:- Operate components such as power assisted steering, automatic gearbox, air conditioner and check that engine runs properly with the additional load
Vehicles with catalyst:- Pull hose of CO measuring pipe
- Run engine for about one minute at 3000 rpm
- At idling speed measure CO content in exhaust tailpipe. The catalyst is OK if the CO content in the tailpipe is lower than at the CO measuring pipe.
Note for vehicles with/without catalyst:- Attach or join together all hoses and connections which were pulled off or separated for the test/adjustment.
If the CO content rises after the idling adjustment with the crankcase ventilation hose attached, this does not mean that the adjustment is not correct. It is due to enrichment from the crankcase as a result of oil dilution caused by frequent stop/start driving. A long fast drive on open roads will reduce the amount of petrol in the oil and the CO content will drop to normal. At short notice this can also be done by changing the oil.
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