RS6 stuttering at low revs
Discussion
Evening
My C7 RS6 is ‘stuttering’ and very jerky at low revs:
Only happens at 1500-2000 rpm under light throttle and disappears above 2200.
No loss of power - pulls smoothly to the red-line, never does it when box is in sport (presumably because it’s never lower than 2200 rpm).
Dealer had had it in twice - not showing any fault codes.
Beginning to really drive me nuts. Car has done 57k, run only on 99 RON fuel and service schedule had been adhered to.
Anyone got any suggestions as to what it might be?
My C7 RS6 is ‘stuttering’ and very jerky at low revs:
Only happens at 1500-2000 rpm under light throttle and disappears above 2200.
No loss of power - pulls smoothly to the red-line, never does it when box is in sport (presumably because it’s never lower than 2200 rpm).
Dealer had had it in twice - not showing any fault codes.
Beginning to really drive me nuts. Car has done 57k, run only on 99 RON fuel and service schedule had been adhered to.
Anyone got any suggestions as to what it might be?
Is this when you're accelerating through those revs or when you're driving at a steady speed within that rev range? I only ask as my OH's BMW 120d does the same if you're driving at a steady speed at around the level where the turbo kicks in. It's as though the turbo can't quite decide whether it should be doing something or not so it keeps kicking in and dropping out and makes the car feel jerky. If I drive in a higher or lower gear so I'm above or below the point where the turbo kicks in I can make perfectly smooth progress.
annodomini2 said:
Mr Gearchange said:
Dealer has checked the plugs and they aren’t causing the issue.
I'm not saying they are, more what is the condition of them after the stuttering, this will tell you if it's a mixture or combustion issue.Fuel filter, dodgy coil pack? If no fault codes I'd recommend a good specialist like VRS to take it out to replicate the symptoms and they could do some live data logging. They will check for things like fuel trims, pressure, lambda/o2 etc. Might throw up a weak spot somewhere. Not expensive to do.
Discombobulate said:
Apologies for stating the bleeding obvious but have you ruled out the cylinder deactivation - felt as a jerk when the car drops to 4 cylinders under light throttle? It is deactivated when in sport 
Not according to the display - it was one of the first things I looked for.Also cylinder deactivation still operates with the box in sport
Digger said:
Hang on . . . so the dealer have had it in twice, & are presumably replicating the issue, yet still handed it back to you without resolving, twice?!
They’ve handed it back once having been unable to replicate it.They’ve now had it back for 5 days and I’ve told them I don’t want the car back until they have solved the problem. One of their techs is using it as his daily until then.
But apparently if the laptop doesn’t show a fault code they don’t know what to do
Edited by Mr Gearchange on Saturday 27th March 13:42
So after 3 weeks they have decided it was the plugs after all, despite telling me that it wasn’t initially.
They then tried to charge me for 4 hours diagnosis to find what was obviously some kind of misfire issue - without having checked the plugs - despite having ample time to do so whilst they had the car in bits to replace the water pump and thermostat housing.
Really glad it’s resolved - and hasn’t been too financially punishing but Jesus Christ - 3 weeks to diagnose faulty plugs causing a misfire?!
They then tried to charge me for 4 hours diagnosis to find what was obviously some kind of misfire issue - without having checked the plugs - despite having ample time to do so whilst they had the car in bits to replace the water pump and thermostat housing.
Really glad it’s resolved - and hasn’t been too financially punishing but Jesus Christ - 3 weeks to diagnose faulty plugs causing a misfire?!
Without defending or attacking anyone (as we don't know all the details) this sounds like a tricky problem to solve. We don't know where they've looked already.
Cars are fiendishly complex things and generally speaking you need a fault code to give you a starting point. They don't tell you what's wrong but they tell you what the ECU can or cannot see. This is your starting point. Audi's diagnostic software ODIS runs a process called 'guided fault finding' that in itself needs something to work from. This usually involves testing, elimination, data-logging, replacement parts... Even guided fault finding sometimes feels a bit scatter gun and not at all customer focused "replace engine ECU and re-test", or "replace engine". That's extreme but you catch my drift I'm sure.
If the ECU can't see anything unusual then you've nowhere to start from. Technicians are expensive so a garage will not allow them to start a job blind and no customer will authorise an unlimited number of billable hours. You can't run a business this way and it isn't helpful to a customer.
The 'obvious' place to look involves watching live data but there's some skill involved in knowing what to look at and how to interpret it. All of this work is near impossible to budget/quote in terms of time or money.
There is within main dealers a tendency to do things "by the book" where sometimes more lateral thinking is required. Even an independent (good, bad, or otherwise) has to be able to reproduce the fault under workshop conditions before they can do anything about repairing it.
Cars are fiendishly complex things and generally speaking you need a fault code to give you a starting point. They don't tell you what's wrong but they tell you what the ECU can or cannot see. This is your starting point. Audi's diagnostic software ODIS runs a process called 'guided fault finding' that in itself needs something to work from. This usually involves testing, elimination, data-logging, replacement parts... Even guided fault finding sometimes feels a bit scatter gun and not at all customer focused "replace engine ECU and re-test", or "replace engine". That's extreme but you catch my drift I'm sure.
If the ECU can't see anything unusual then you've nowhere to start from. Technicians are expensive so a garage will not allow them to start a job blind and no customer will authorise an unlimited number of billable hours. You can't run a business this way and it isn't helpful to a customer.
The 'obvious' place to look involves watching live data but there's some skill involved in knowing what to look at and how to interpret it. All of this work is near impossible to budget/quote in terms of time or money.
There is within main dealers a tendency to do things "by the book" where sometimes more lateral thinking is required. Even an independent (good, bad, or otherwise) has to be able to reproduce the fault under workshop conditions before they can do anything about repairing it.
Mr Gearchange said:
But apparently if the laptop doesn’t show a fault code they don’t know what to do
Mr Gearchange said:
but Jesus Christ - 3 weeks to diagnose faulty plugs causing a misfire?!
For me, these two quotes sum up almost all that's wrong with the modern car + main dealer combination.Gassing Station | Audi, Seat, Skoda & VW | Top of Page | What's New | My Stuff