hesitation in WOT at hig RPM

5.0 V10 50v biturbo - 571 bhp
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argo8
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hesitation in WOT at hig RPM

Post by argo8 » Mon Sep 20, 2021 10:05 am

Hello, I have an audi rs6 v10 tfsi With which I am very happy because its performance in a straight line is amazing at the level of other sports cars that I have
I cannot find out what improvements the previous owner made.
my car is rated for +800 Hp according to the documentation
as far as I have been able to find out, it has large turbos installed
HFP loba motorsport pumps.
ecu remapping
exhaust and sport cats.

It has new spark plugs and oem air filter
the car runs very strong and very well, but when it reaches the top of the rpm counter it suffers hesitation or small jerks when accelerating.

I think you can fix it with new software?
From your experience have you seen this in a car?
what do you think the problem may be?

Thank you so much

welwynnick
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Re: hesitation in WOT at hig RPM

Post by welwynnick » Mon Sep 20, 2021 10:15 am

If it hesitates at high rpm I wouldn't drive it at high rpm.

There's a risk that you have a fuel supply shortfall, and if you go lean at full power you may suffer from detonation and you'll damage the engine very quickly.

Is this a new problem or has the car always behaved like this?

Do you know who modified, and who tuned the car, and when?

You could start by replacing the fuel filter.

Next thing would be to look at mixture strength correction factors, or to monitor lambda sensor outputs when driving on the road.

Nick

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IanH755
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Re: hesitation in WOT at hig RPM

Post by IanH755 » Mon Sep 20, 2021 10:49 am

I know this may sound silly, but with your car having 800+hp have you turned the ASR/ESP (Traction Control) OFF before you go full throttle?

My car with 900hp and (4 new Michelin Pilot Sport 4S tyres) really needs the ASR/ESP switched OFF to get full power every time you go full throttle because, if you keep the ASR/ESP switched ON, this can also cause "random" power dips at high RPM etc.

However, if you switch ASR/ESP off and it still has hesitation at high RPM then your car will have an actual fault somewhere which needs fixing, most likely fuel, which needs fixing.
***OLD*** Daytona C5 RS6 Avant - MRC'd - 500HP & 820NM (PistonHeads Link).

***NEW*** Daytona C6 RS6 Avant - MRC'd - 955HP & 1200NM (PistonHeads Link)

VaudiGR
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Re: hesitation in WOT at hig RPM

Post by VaudiGR » Mon Sep 20, 2021 12:34 pm

Additionally high rpm hesitation may be a coil issue in which case check fault codes and see if a particular cylinder is acting up

argo8
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Re: hesitation in WOT at hig RPM

Post by argo8 » Mon Sep 20, 2021 6:13 pm

the coils are new
I can't know who tuned the car in the past
is there any way to log data
What device or software is used for this car?

VaudiGR
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Re: hesitation in WOT at hig RPM

Post by VaudiGR » Mon Sep 20, 2021 6:15 pm

argo8 wrote:the coils are new
I can't know who tuned the car in the past
is there any way to log data
What device or software is used for this car?
VCDS also known as Vagcom. However there are other gadgets like obdeleven which can show you fault codes.
If you feel hesitation hopefully there will be codes stored

argo8
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Re: hesitation in WOT at hig RPM

Post by argo8 » Mon Sep 20, 2021 6:19 pm

I think it is a diagnostic device (there is no fault)
I need a device such as HP TUNERS
that allows you to mediate engine data and modify it

VaudiGR
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Re: hesitation in WOT at hig RPM

Post by VaudiGR » Mon Sep 20, 2021 7:42 pm

I don't know which one is used for these ECUS

BobBobson
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Re: hesitation in WOT at hig RPM

Post by BobBobson » Tue Sep 21, 2021 8:40 am

IMHO it is impossible to diagnose a heavily modified car over the internet. Even if you get access to modify the ECU code, what parameters are you going to change if you don’t understand the problem?

Surely you need something like VCDS and then log cylinder misfires, knock events, fuel pressure, lambda and probably some more I haven’t thought of during a misfire. Until you’ve done this you’ll have no idea what you’re chasing.

We don’t even know if the car has ever worked or if this is a new issue. If it’s previously run well then jumping to remapping seems like a really bad idea.

argo8
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Re: hesitation in WOT at hig RPM

Post by argo8 » Tue Sep 21, 2021 9:24 am

in the workshop they say that probably
It is the limit of the gearbox that cannot handle the high torque and therefore power cuts occur
the explanation does not convince me.
What is the limit that the gearbox supports?

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IanH755
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Re: hesitation in WOT at hig RPM

Post by IanH755 » Tue Sep 21, 2021 9:59 am

argo8 wrote:
Tue Sep 21, 2021 9:24 am

What is the limit that the gearbox supports?
The Gearbox ECU has a "do not exceed" torque limit set in the software to protect the gearbox, IIRC it's around 950nm. This limit can be removed by remapping the gearbox ECU, which is why cars mapped by MRC Tuning etc can hit 1000nm+ but for a car with over 800hp you would also usually (but not always) have a uprated gearbox fitted rather than using the standard gearbox so that it can cope with the extra torque (usually 1100-1200nm+ on cars with over 800hp).

So what the garage is telling you about the gearbox could be correct, depending on who has mapped the car it might be ONLY the engine ECU which is mapped and the gearbox ECU might still have it's torque protection software there.

However for your fault the peak torque is usually 3500rpm and it reduces at higher RPM so if your problem is only at high RPM it is unlikely to be the gearbox torque limiter. I agree with others on here, you really need something like VCDS or, at a minimum, an OBD-II reader just to check for fault codes and also live monitor things as the engine is at high rpm as you may see things like the fuel pressure falling or maybe a cylinder misfire etc as neither of these would put a warning message on the dashboard but both would be logged as a fault.
***OLD*** Daytona C5 RS6 Avant - MRC'd - 500HP & 820NM (PistonHeads Link).

***NEW*** Daytona C6 RS6 Avant - MRC'd - 955HP & 1200NM (PistonHeads Link)

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