Audi A6 3.0 tdi hunting revs
Discussion
Chaps, had the A6 a few weeks now (great car). However, noticed occasionally when engine is warm and restarted that the revs will hunt at idle until you drive off. Pulls cleanly and doesn't do it again at junctions, when the clutch is depressed or in neutral. Was thinking about cleaning the maf anyway but any thoughts..??
Not sure Dr G would the dpf regen throw a light up on the dash..?? I know the car hadn't done many miles in the last couple of months before we bought it but we have taken it on a good few runs since. I'm away again this week on a 300 mile round trip so maybe an idea to kick it's arse a bit and see whether it improves matters.
It's curious because it doesn't do it from cold just when restarted from hot say after stopping at services but usually a quick blip of the throttle seems to cure it.
It's curious because it doesn't do it from cold just when restarted from hot say after stopping at services but usually a quick blip of the throttle seems to cure it.
Dr G said:
Not generally troublesome on 3 litres and yours might well be (just) old enough not to have one blueg.
Doesn't sounds like a DPF issue from your description; does the car smoke or use oil excessively?
Build was jan/feb 2007Doesn't sounds like a DPF issue from your description; does the car smoke or use oil excessively?
Just checked, its prep only
Edited by blueg33 on Wednesday 25th April 14:30
Dr G said:
Not generally troublesome on 3 litres and yours might well be (just) old enough not to have one blueg.
Doesn't sounds like a DPF issue from your description; does the car smoke or use oil excessively?
It doesn't use any oil but I did notice a bit of diesel smoke when my Mrs started up and drove off in it the other day...Doesn't sounds like a DPF issue from your description; does the car smoke or use oil excessively?
ETA: mines also the 3.0tdi but a 2005/2006 MY with the following code: 7GN = Emission standard, EU4, DPF preparation
I've been thinking about this, and having a bit of a dig arround at work. We have only ever had one V6 TDI properly hunting, revs up and down from 600 to 1000 rpm, and the engine ECU and fuses + connectors within the ECU box were all underwater.
Inlet manifold flaps are common but generally there is no change in the how the engine runs.
There is a know issue with rough idle and white smoke when the engine idle for a long time, but you wouldnt get hunting, just uneven idle like a slight misfire.
Be interested to know what you find.
Inlet manifold flaps are common but generally there is no change in the how the engine runs.
There is a know issue with rough idle and white smoke when the engine idle for a long time, but you wouldnt get hunting, just uneven idle like a slight misfire.
Be interested to know what you find.
Tame Technician said:
I've been thinking about this, and having a bit of a dig arround at work. We have only ever had one V6 TDI properly hunting, revs up and down from 600 to 1000 rpm, and the engine ECU and fuses + connectors within the ECU box were all underwater.
Inlet manifold flaps are common but generally there is no change in the how the engine runs.
There is a know issue with rough idle and white smoke when the engine idle for a long time, but you wouldnt get hunting, just uneven idle like a slight misfire.
Be interested to know what you find.
Thanks TT... You've got me thinking now maybe 'hunting' is the wrong terminology.Inlet manifold flaps are common but generally there is no change in the how the engine runs.
There is a know issue with rough idle and white smoke when the engine idle for a long time, but you wouldnt get hunting, just uneven idle like a slight misfire.
Be interested to know what you find.
I will try and explain a bit better what is going on. This only ever seems to happen when the car is warm so starting from cold the revs are bang on - for the sake of argument let's say 900rpm. However, if I were to drive for a few miles then stop and return to the car and restart the revs will sit at 900 rpm but then drop to say 700/800 rpm and then back up to steady idle so on and so forth. It will do this a number of times although disappears with a blip of the throttle and the idle will be back to normal.
There is no white smoke from the exhaust even when left idling for some time. It could just be a rough idle as suggested above.... Incidentally where is the ECU and box located..?? I am paranoid about water leaks from the scuttle drain holes as had a few problems in the past with other cars getting clogged up with leaves so might check this one to be on the safe side.
Just to add to info, since owning my car last August besides usual servicing:-
i) had chain rattle fixed ie engine+tranny out
ii) investigated both plenum chamber electrics AOK no current or past issues I could see
iii) due to doing retro fits and fixing rear washer pipework issue(as I own an Avant)had seats,carpets and most trim bar dash,roof and door ones off no wiring or detectable issues
I am considering a battery change as mine is original Audi one, had that checked twice no issues...
I have basically worked through a lot of stuff and am stumped
...
Any suggestions guys...
i) had chain rattle fixed ie engine+tranny out
ii) investigated both plenum chamber electrics AOK no current or past issues I could see
iii) due to doing retro fits and fixing rear washer pipework issue(as I own an Avant)had seats,carpets and most trim bar dash,roof and door ones off no wiring or detectable issues
I am considering a battery change as mine is original Audi one, had that checked twice no issues...
I have basically worked through a lot of stuff and am stumped
...Any suggestions guys...
You ideally need to get vag-com connected with someone that knows how to use it,to regenerate the dpf if one is fitted you need to put it that mode via vag-com and go for a long drive till it tells you its done, usualy involves holding it in gear at fairly high revs..
not sure if they do it themselves as i only see cars with issues.
I suspect a small air leak or a faulty afm but id plumb for an air leak if the idle is only sometimes erratic,switching air-con on and off can sometimes trigger the fault.
not sure if they do it themselves as i only see cars with issues.
I suspect a small air leak or a faulty afm but id plumb for an air leak if the idle is only sometimes erratic,switching air-con on and off can sometimes trigger the fault.
Hi, I have VAGCOM/VCDS purchased from Gendan... no faults logged in any modules...
I have no DPF, mines an early 3.0 TDi... PR codes for car off data sticker confirm this, local dealer has also confirmed via VIN check over the phone...
Before chain rattle fix I had this issue... I thought when engine removed/rebuilt it would go away... sadly still there...
I am going to try some measuring blocks in engine module... any suggestions to what to look for guys?
On early versions of throttle valves the gearing for flap can go would this cause the issue if worn or on way out??
I have no DPF, mines an early 3.0 TDi... PR codes for car off data sticker confirm this, local dealer has also confirmed via VIN check over the phone...
Before chain rattle fix I had this issue... I thought when engine removed/rebuilt it would go away... sadly still there...
I am going to try some measuring blocks in engine module... any suggestions to what to look for guys?
On early versions of throttle valves the gearing for flap can go would this cause the issue if worn or on way out??
Removed the throttle body... three torx screws... one hose clip.. one elc.connection
On moving butterfly it would stick at times... when check internals teeth on cog which butterfly is on worn...
Replaced not fix issue
Under instruction from another forum I removed MAF elec connection all issues gone
Now investigating what will solve the issue... so will post back...
On moving butterfly it would stick at times... when check internals teeth on cog which butterfly is on worn...
Replaced not fix issue
Under instruction from another forum I removed MAF elec connection all issues gone
Now investigating what will solve the issue... so will post back...
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