A3 8P 3.2 - TAME TECHNICIAN
Discussion
Tame Technician,
I'm nearly there sorting all the niggly little issues with my A3, and last few bits on the list are:
The valve in the exhaust tail pipe is not closing
Slight vibration from the engine on idle/hesitation around 2k rpm
With the valve in the exhaust I don't know where to start, any common reasons for it to fail? Also, what is the 'proper' name for it?
As for the engine, I have changed the spark plugs (improved the situation), air filter and fuel filter. No problems between idle and 2k, and no problems above 2k. No warning lights, no loss of power any where else in the rev range. Vibration is not like a typical missfire and fuel economy is ok. Not an engine mount either....
Any help much appreciated!
I'm nearly there sorting all the niggly little issues with my A3, and last few bits on the list are:
The valve in the exhaust tail pipe is not closing
Slight vibration from the engine on idle/hesitation around 2k rpm
With the valve in the exhaust I don't know where to start, any common reasons for it to fail? Also, what is the 'proper' name for it?
As for the engine, I have changed the spark plugs (improved the situation), air filter and fuel filter. No problems between idle and 2k, and no problems above 2k. No warning lights, no loss of power any where else in the rev range. Vibration is not like a typical missfire and fuel economy is ok. Not an engine mount either....
Any help much appreciated!
Edited by bn9af on Sunday 6th December 23:11
To soon for streched chains or anything nasty like that I think.
Exhaust flap is vacuum operated, you can test the flap mechanisim its self with a vacuum pump. But I'd say there is a vacuum leak somewhere and it could cause both issues.
Coils are pretty rubish on the VR6 engine, so if it develops from a vibration to an obviousd single cylinder misfire, its gonna need at least one of those.
Have you read the fault memory. Anything else not right vacuum related?? Secondary air etc.
Exhaust flap is vacuum operated, you can test the flap mechanisim its self with a vacuum pump. But I'd say there is a vacuum leak somewhere and it could cause both issues.
Coils are pretty rubish on the VR6 engine, so if it develops from a vibration to an obviousd single cylinder misfire, its gonna need at least one of those.
Have you read the fault memory. Anything else not right vacuum related?? Secondary air etc.
Edited by Tame Technician on Monday 7th December 22:43
No not checked the fault history, will get onto that as soon as, as with the coils, is it worth diconnecting them individually to see if there one thats playing up?
As for the exhaust flap, is there a vacuum pipe running from the engine to the tail pipe? or is it an actuator which is electronically controlled?
As for other vacuum related things the brakes are good, but don't know what your mean by secondary air.
As for the exhaust flap, is there a vacuum pipe running from the engine to the tail pipe? or is it an actuator which is electronically controlled?
As for other vacuum related things the brakes are good, but don't know what your mean by secondary air.
bn9af said:
No not checked the fault history, will get onto that as soon as, as with the coils, is it worth diconnecting them individually to see if there one thats playing up?
As for the exhaust flap, is there a vacuum pipe running from the engine to the tail pipe? or is it an actuator which is electronically controlled?
As for other vacuum related things the brakes are good, but don't know what your mean by secondary air.
(1) As for the exhaust flap, is there a vacuum pipe running from the engine to the tail pipe? or is it an actuator which is electronically controlled?
As for other vacuum related things the brakes are good, but don't know what your mean by secondary air.
Check the fault memory BEFORE you disconnect anything!, unpluging one coil at a time, can help show which one is playing up, if one is, but the misfire detection within the cars ECU is normally much better than your ear (not always) so before you induce a load of misfires, see what its got to say for itself.
(2) The vacuum pipe from the exaust will go to a solnoid at some point so the ECU can open and close it, normally if they play up, the soloniod works fine, theres just no vacuum getting to the solonoid.
People take them off on the V8 RS4's so there loud all the time, but forget to plug the pipe and the loss of vacuum makes all the other vacuum operated items stop working, and they wonder why teh car is flat and the engine light comes on.
(3) Secondary air injection is a way of getting "basically 1991 VR6 engines" through current EU emmisions specs by pumping air into the exhaust on cold start. Warms up the Cat and O2 sensors quicker than if it wasnt there.
The valves that allow the fresh air into the exaust are opened by vacuum actuators by a solonoid. Often the first sign of a vacuum leak, hose split or come off etc is the ECU reports Sencondary air flow bellow spec.
Cant remember off the top of my head where the vacuum reservior is or where the various soloniod are, will try and find out for you, in the mean time check the valve on the exhaust with a ahand vacuum pump, it might just be stuck. and check the fault memory before you do anything else.
if you don't have any faults stored and the coils etc seem fine you could check the condition of the throttle housing these tend to get really dirty and cause lumpy idle and hesitation on revs, remove the butterfly housing and give it a good clean, might req re-setting the the throttle hosing back to basic setting using vag.com or other vw software as the ecu adjusts the the butterfly to suit its conditions/idle.
Tame Technician said:
To soon for streched chains or anything nasty like that I think.
Exhaust flap is vacuum operated, you can test the flap mechanisim its self with a vacuum pump. But I'd say there is a vacuum leak somewhere and it could cause both issues.
Mine had the camchain changed this year at 45k (2004 car), although I'm not convinced that was the problem due to a series of subsequent problems that got the dealer throwing parts at it until it was 'fixed'.Exhaust flap is vacuum operated, you can test the flap mechanisim its self with a vacuum pump. But I'd say there is a vacuum leak somewhere and it could cause both issues.
I thought the solenoid for the exhaust flap was electric? AFAIK it's there for low-speed noise reduction, read on a forum that leaving it open all the time actually increased power (on an R32 anyway but I think the same applies) and as such many people disconnect them/fix in the open position.
catso said:
Tame Technician said:
To soon for streched chains or anything nasty like that I think.
Exhaust flap is vacuum operated, you can test the flap mechanisim its self with a vacuum pump. But I'd say there is a vacuum leak somewhere and it could cause both issues.
Mine had the camchain changed this year at 45k (2004 car), although I'm not convinced that was the problem due to a series of subsequent problems that got the dealer throwing parts at it until it was 'fixed'.Exhaust flap is vacuum operated, you can test the flap mechanisim its self with a vacuum pump. But I'd say there is a vacuum leak somewhere and it could cause both issues.
I thought the solenoid for the exhaust flap was electric? AFAIK it's there for low-speed noise reduction, read on a forum that leaving it open all the time actually increased power (on an R32 anyway but I think the same applies) and as such many people disconnect them/fix in the open position.
Yes your quite right about the noise reduction and people leaving them off for a bit more noise/power.
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