Robbie512

Audi Cab 1.8 manual is hard to start, when it starts it runs erratically reving up and down without the throttle being touched. This problem is intermittant with the car somedays will run behaving itself then suddenly it starts playing up again. Diagnostics give Throttle body error code that the internal valve is at fault. so far 4 throttlebodies have failed to fix the issue (2 secondhand and 2 new). Have carried out head overhaul including reseat and new valves and seals, new head gasket, new injectors, new spark plugs, and leads, new MAFF and so now I am going the change the ECU. Anyone else had this problem. Help please if you can. Rob

Rusty Spokes

Robbie..are you in the USA? I ask as the Audi Cabriolet last year here was 1998..the B4 Cabriolet continued sales in Europe till 2000. We also did not get the 1.8 engines here. Only the 2.8.

So here we don't have much experience with the 1.8 engines. My opinion would be you have an air leak somewhere..hard to start and idle problems usually indicate an air leak..vacuum line loose, etc.

The German Cabriolet website has information that can be helpful as they have the 1.8 engines.

Audicabrio.info | Faszination & Technik - Das Infoportal

CRAZY_RUSSIAN

is it fly by wire? if so, try replacing your gas pedal. if its a cable, ignore that one. hos is your MAS?
check for vacuum leaks and possibly a broken wire somewhere. also, coolant test your temp sensor for the ECU.

Robbie512

Thanks crazy Russian have replaced the sensor today and at least the erratic running has ceased, still a little difficult to start, changed other temp sensor as well but has not helped the starting. However, it was 2 degrees above zeroe tonight and after a little perseverance she started and once warmed up a little she ran normally. will get the circuit tester out at the weekend to see if there are any broken wires. Had a roof problem earlier this year, after replacing the hydraulics and the slaves that turned out to be a broken wire, so good advice check for broken wires first. Thanks again.

CRAZY_RUSSIAN

I'm glad that helped :-)
there are several issues that can contribute to cold start problems. vacuum leaks, old or inappropriate oil, dirty injectors, or leaky injector seals. Replaced fuel filter in the last 40k? how about air filter? spark plugs?