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Loss of power

Posted: Wed Aug 20, 2014 8:34 am
by qwick69
Hello.
Has anyone else experienced loss of power when overtalking or pulling away hard?
It is an intermittant fault that has happened about 3 or four times now in the last 3000 miles.The car has now covered 5k miles. I put my foot down and the car wants to go, but seems to be held back for a few seconds. It pulls, but only very slightly, it then seems to clear and goes as you would expect.
The last time it happened, I was trying to overtake.... A bottom clenching moment I can tell you.
Going to book it in to Audi to investigate, but the trouble is, it doesnt happen all the time, so I bet they wont be able to find anything wrong with it.

Re: Loss of power

Posted: Wed Aug 20, 2014 9:04 am
by wildbore
Cannot speak for Audi and the ZF box, but this is a common enough experience in Mercedes' autos. Sometimes the box gets wrong-footed and the ECU refuses power to the engine until the box has "sorted itself out" for want of a better expression. It usually happens when kickdown is engaged. It happens only very occasionally and is almost impossible to reproduce on demand.

Re: Loss of power

Posted: Wed Aug 20, 2014 4:05 pm
by W8PMC
I'm no expert but would tend to agree with above & think it's more related to the ECU & transmission rather than an actual fault. Is a real shame that Audi put a regular slush box in the RS6 rather than an S-Tronic but that takes nothing away from the cars performance. Computer probably said no as the box was in sleepy mode so trying to awaken the beast at very short notice possibly caught the computer napping.

Re: Loss of power

Posted: Wed Aug 20, 2014 4:11 pm
by doodlebug
W8PMC wrote:I'm no expert but would tend to agree with above & think it's more related to the ECU & transmission rather than an actual fault. Is a real shame that Audi put a regular slush box in the RS6 rather than an S-Tronic but that takes nothing away from the cars performance. Computer probably said no as the box was in sleepy mode so trying to awaken the beast at very short notice possibly caught the computer napping.
Hardly a regular slush box. The ZF 8 is widely acclaimed as one of the best boxes out there. S-Tronic cannot handle the torque. The RS6 only shifts marginally slower than the RS4, the box is perfectly matched IMO. Also lighter than double clutch....

The new breed of slush-o-matics are the future.

Re: Loss of power

Posted: Wed Aug 20, 2014 4:47 pm
by bam_bam
TCU brain fart. Drive with paddles, problem sorted.

Re: Loss of power

Posted: Wed Aug 20, 2014 4:58 pm
by VARSITY
bam_bam wrote:TCU brain fart. Drive with paddles, problem sorted.
Im beginning to think that BAM BAM has all the answers, to life and everyfink.

Re: Loss of power

Posted: Wed Aug 20, 2014 5:13 pm
by W8PMC
doodlebug wrote:
W8PMC wrote:I'm no expert but would tend to agree with above & think it's more related to the ECU & transmission rather than an actual fault. Is a real shame that Audi put a regular slush box in the RS6 rather than an S-Tronic but that takes nothing away from the cars performance. Computer probably said no as the box was in sleepy mode so trying to awaken the beast at very short notice possibly caught the computer napping.
Hardly a regular slush box. The ZF 8 is widely acclaimed as one of the best boxes out there. S-Tronic cannot handle the torque. The RS6 only shifts marginally slower than the RS4, the box is perfectly matched IMO. Also lighter than double clutch....

The new breed of slush-o-matics are the future.
What's not regular about it? May well be regarded as one of the best boxes out there but better off in vehicles that demand smooth over quick. Audi RS's have always had a bit of an issue with transmissions as was a weak spot in the C5 (i had 2 replaced) & a few let go with the C6. TBH it was only on cars i guess that were pushed harder as driven under regular load i bet they were & are more than up to the job.

As for power & torque, that used to be valid but dual clutch boxes under any other Marque can handle high torque outputs nowadays, but clearly the Audi one perhaps can't.

I've driven the same scenarios in BMW's recently & while their ZF8 is a fabulously smooth box & a marvel to drive, it's not got even a hint of the dynamics of the M-DCT.

I can't take anything away from the C7's box though as it does feel very capable in the cars i've driven.

Re: Loss of power

Posted: Wed Aug 20, 2014 6:01 pm
by doodlebug
Hmm, not sure there are many dual clutch gearboxes that cope with 700Nm plus out of the box, fezzas etc apart.

It's plenty snappy enough for the C7.

Merc are still using slush boxes for their big AMG stuff.

Re: Loss of power

Posted: Wed Aug 20, 2014 6:55 pm
by W8PMC
doodlebug wrote:Hmm, not sure there are many dual clutch gearboxes that cope with 700Nm plus out of the box, fezzas etc apart.

It's plenty snappy enough for the C7.

Merc are still using slush boxes for their big AMG stuff.
I thought the E63 had a Dual Clutch? The M5 certainly has & the torque in an F10 M5 must be on a par with the RS6 as the power is & both are TT V8's. R8's now use the S-Tronic & Porsche have been using PDK in the Turbo & Turbo S for a while & both those cars kick out some torqs.

Tiptronic boxes in RS's to date have been far from bullet proof so i don't agree they're any more capable at handling RS power than an S-Tronic would be but i'm no mechanic:)

No denying the RS6 is a formidable beast though & they sound epic.

Re: Loss of power

Posted: Wed Aug 20, 2014 7:04 pm
by doodlebug
E63 box is pre-historic six speed jobby! Granted 991 TTS is 700/750 and its PDK is awesome. R8 doesn't come close on the torque figures,

I think C6 has been bomb proof. Loads of cars running 1000Nm plus with a stock box. C5 was a different matter.

Re: Loss of power

Posted: Wed Aug 20, 2014 8:56 pm
by W8PMC
It's a new 7 Speed MCT Transmission with MCT translating to Multi Clutch Transmission in the E63 according to t'internet. I'm also sure apart from the outgoing C63, this new box is adorning all current & upcoming AMG's (could be wrong though).

Not so sure the C6 was bombproof as i know of a few whose boxes went South, but overall it did appear stronger than the C5.

http://www.topspeed.com/cars/mercedes/2 ... 36070.html

Re: Loss of power

Posted: Wed Aug 20, 2014 9:05 pm
by doodlebug
Aye, they've changed the gearbox recently. It was a six speed slosh when I was looking. MCT hasn't made it a lot, if any quicker to 60.

Interesting, not heard of a single C6 with a failed box.

Double clutch gearboxes have been much more prone to failure.

Re: Loss of power

Posted: Wed Aug 20, 2014 9:32 pm
by HYFR
Have heard of a few rs5 and rs3 DSG going up the swanny, lest forget the 3.2 V6 DSG

The ZF 8speed is where it's at

Test drove it in the F TYPE R and it makes a DSG redundant as the shifts are blind of any eye quick and you still get the drama and theatre of gears shifting up and down with the farts and pops and bangs and rev match, but then the ultimate smoothness around town

It's a gem

And can handle big torques

Re: Loss of power

Posted: Thu Aug 21, 2014 11:24 am
by W8PMC
doodlebug wrote:Aye, they've changed the gearbox recently. It was a six speed slosh when I was looking. MCT hasn't made it a lot, if any quicker to 60.

Interesting, not heard of a single C6 with a failed box.

Double clutch gearboxes have been much more prone to failure.
The E63S with the MCT is probably the quickest such car on the road with a 0-62 of 3.6secs which eclipses it's competition so the new box has made a huge difference.

I can't argue the point regarding DCT reliability other than i've never had one fail in the 3 cars i've owned with them but have had 2 Audi tiptronic boxes go bang. Agree the new ZF is hugely improved but i'd certainly still prefer a twin clutch for enthusiastic driving & it appears the industry tends to agree given the cars that have them fitted as standard.

Re: Loss of power

Posted: Thu Aug 21, 2014 11:33 am
by W8PMC
HYFR wrote:Have heard of a few rs5 and rs3 DSG going up the swanny, lest forget the 3.2 V6 DSG

The ZF 8speed is where it's at

Test drove it in the F TYPE R and it makes a DSG redundant as the shifts are blind of any eye quick and you still get the drama and theatre of gears shifting up and down with the farts and pops and bangs and rev match, but then the ultimate smoothness around town

It's a gem

And can handle big torques
Really? It's a nice box in all i've driven with it fitted, but the drama is far more manufactured (software) than mechanical which is why personally i feel the dual clutch application is far better suited to performance cars. Agreed it may not be perfect & agree it's no doubt failed in some applications, but then so has the ZF 8 speed. I guess where the ZF8 may have a slight advantage is the night/day ability so in Sports mode/flappy paddle it is quick & makes all the right noises, but in slush mode it's probably smoother than a dual clutch for cruising. That said, i still feel a modern DSG will perform better across the performance spectrum & give better feedback, but perhaps at the slight sacrifice of out & out smoothness when cruising.

I could of cause be talking total bollox as can only speak from my experiences :drink: