Audi 80Tdi Erratic Running

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Tue 14 Feb 2006 23:27
Audi 80Tdi Erratic Running - Alek Smart
Hello all.
1992 A 80Tdi suddenly started acting up.
Loss of power,as if in limp home mode then an equally sudden bout of erratic running as if the ignition was being flicked on and off.
All ECU block connections and Ignition Switch connections checked and found ok.....Any thoughts ?
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Tue 14 Feb 2006 23:50
Audi 80Tdi Erratic Running - Screwloose
Alek

Engine control relay?
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Thu 16 Feb 2006 13:59
Audi 80Tdi Erratic Running - Spanner
At this age of car, check for air leaks from intake side, i.e rubber air intake pipe from air-filter housing to inlet manifold. Check security of these pipes and joints and make sure all jubilee clips (or similar) are tight. Make sure all vacuum hoses/pipes are also secure with no sign of perishing.
The symptoms can also be a sign of a problem with the air-flow meter. Having said that, being a diesel, if any of the low pressure side of the fuel system are leaking and sucking in air then you will experience surging and general rough running.
A quick rule is the low pressure side of the fuel system is the fuel tank and hoses incl filter and housing - right up to the diesel injection pump. These hoses are often rubber or rigid plastic. Check carefully for loose connections or perishing.

The high pressure side fuel lines are metal and you can find them on the injection pump and injectors. You will notice small bore rubber hoses coming from the injectors. These are leak-off pipes and take unused diesel (at low pressure) back to either the pump or back to the tank. If these leak, they can cause running problems.
Check the simplest things first before condemning the ECU etc, but don't feel for leaks around the high pressure pipes with the engine running, just in case you have a leak at the injector unions. Most diesel pumps run at 170 bar (a bar being 14.7 pounds per square in) or 2,499 psi !

Andrew
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