Lack of Boost and engine response below 2,500rpm

[shanek]

Hi Guys,

I am suffering from a very strange issue with my RS6 PE and just wondering if any or you guys have suffered anything similar?

When trying to accelerate with anything less than 2,500rpm, there is very little power/torque available and when looking on the boost gauge, there is almost no boost available. It drives like an old school 80's turbo car with loads and loads of lag.
Once past 2,500rpm, normal (ish) service is resumed with ok torque and power available but I have noticed that the overboost function is not operating. I have also experienced some engine hesitation when in the higher rev ranges like there is some fuelling, air or ignition issues.

My car has been in the stealers since the middle of last week but no errors have been logged, Audi Technical say there are no known issues (so I cant possibly be having any issues) and they have no other RS6 or RS7 in to allow a back to back comparison.

Compared to how the car was, it feels so slow and lethargic with no real throttle response and when trying to pull onto roundabouts or out of junctions from a standstill, it can feel quite dangerous due to the lack of engine response below 2,500rpm.

Has anyone else had anything similar?

[rtd]

I experienced similar but when I was having an issue with my stop/start system and stealer couldn’t locate any faults - I complained to Audi UK - who arranged for car to be taken back into stealers and they replaced parts on car as per directions from Audi UK - been fine ever since. Maybe worth calling them?


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[innercry666]

Mine has felt a bit sluggish at times recently. Definitely lethargic at times so much so I thought the discs were binding in the calipers so had them checked but no issues.

Funnily enough I had a Start / Stop error showing for two journeys the other day but has now cleared. The car is in Audi next week for an oil change and new plugs so will get them to look at it.

What was the issue with the start / stop do you know?

[rtd]

Audi UK, advised stealer to replace fuel pumps and something else I think - it’s not missed a beat since. If you have an issue and stealer can’t find any faults then best thing is to call Audi UK. However, remember that if the wheel is turned, the AC is on and if it’s on an uneven surface, slope or incline the system won’t engage. There is some info on this in the manual.


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[crashley]

How do you see the boost gauge? I remember having it, but have subsequently faffed around and lost it.

[shanek]

Its displayed on the drivers display when in 'Lap Timer' mode.

[innercry666]

Cheers rtd. Do you know if there is a TPI on this?

The last time I rang Audi UK I got nothing but incompetence! I'm amazed they had the technical knowledge to advise the stealer of anything!

[MikeFish]

I wouldn't expect much boost below 2500rpm. That sounds normal to me. However, you say it feels different so sounds like there is a fault. Not wanting to state the obvious but have you checked to make sure it is in Dynamic and not Comfort as that will affect throttle reposnse which could be described as hesitation. This can easily happen if you use the spare key for example, as drive mode will be set the same as the last time that key was used.
And with this hot weather is it defo not heat soak?

[rtd]

To be fair the person I spoke to sounded just like some call centre operative - but the fact that I wasn’t prepared to just get off the phone prompted him to talk to other colleagues and then it got escalated. And then that same evening the service manager at the stealers rang me to get the car in - said he’d been advised by Audi UK, and they would need car for a week. Where are u based? No TPI flagged.


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[drhex]

It is on the lap timer in FIS.
Florian

[shanek]

I wouldn't expect much boost below 2500rpm. That sounds normal to me. However, you say it feels different so sounds like there is a fault. Not wanting to state the obvious but have you checked to make sure it is in Dynamic and not Comfort as that will affect throttle reposnse which could be described as hesitation. This can easily happen if you use the spare key for example, as drive mode will be set the same as the last time that key was used.
And with this hot weather is it defo not heat soak?

Hi Mike,

Its pretty much the same regardless what Drive mode its in.
It would be interesting to see what another car behaves like so here is the situation: With Dynamic mode selected and in manual on the gearbox, at approx 30mph with either 4th or 5th gear selected (whichever equates to about 1,600rpm), floor the accelerator while watching the boost gauge and waiting for torque delivery.
As per Audi data, peak torque should be available from 1,750rpm with peak overboost torque availabe from 2,500rpm. My car feels like a 1.4 petrol with no torque and no turbo boost until engine rpm gets above 2,500rpm at which stage, some torque appears but nowhere near the normal amounts I am accustomed to.

From memory (as its been such a long time since it last worked correctly) engine response and torque delivery should be almost immediately after the accelerator pedal is mashed, not having to wait the 5-10 seconds it takes for the rpm to rise.

If anyone can let me know how their cars responds just so I'm not barking up the wrong tree?

[MikeFish]

Yes torque is pretty much there all the time. My point was that I wouldn't expect the boost gauge to show much until about 2500 rpm onwards. I'll try the Ted tout later but first thing I ever notice when test driving was that it would just shift whenever floored.

Is it actually over boosting? The boost gauge should go red when on over boost. Try flooring on a slight incline and looking at the boost gauge.

[MikeFish]

30mph in 4th or 5th sounds pretty low, I'd expect it take a while to get going at that sort of speed and high gear, but I'll try it.

[Markp]

What is the box doing? Does it feel the same if you manually change down?

[MikeFish]

I just tried it.
30mph and 1600rpm is in 5th. Mine feels slow on this test too as it is way to low a gear for that speed. If it was in auto you'd be fine and be in triple digits in no time but in manual and in 5th then you might as well be in a 1.4 diesel.
mine does go straight into overboost and boost start very low and slowly rises.
tried putting in manual and flooring at 2000 rpm a few times but nothing really happens very quickly. Do the same in auto and bye bye.