Engine Rough at 2300rpm, Normal?

4.2 V8 40v biturbo - 450 bhp
4.2 V8 40v biturbo - 480 bhp (plus)
graybags
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Engine Rough at 2300rpm, Normal?

Post by graybags » Fri Jan 25, 2008 1:41 pm

Although I am new to RS6 ownership, I'm not convinced that my engine is running correctly.

Although it is quite smooth when driving gently, it gets rough as the revs/load increase. When overtaking, the exhaust note gets much louder without a huge increase in acceleration. The push-in-the-back is quite gentle.

One specific symptom is as follows: In neutral, gradually increase the revs until around 2300. Here the engine starts to run roughly (misfire?) and the balance goes so that the whole car vibrates (like running on 7 cyl). Do other people's engine do the same? I'm told that this is normal.

It's a standard engine and there are no error codes.
It has just had the full 40K service, including plugs, which has made no difference.

Please tell me this isn't normal. My Wife's 2.0TT is as quick.

Many thanks, Graham

andyt
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Re: Engine Rough at 2300rpm, Normal?

Post by andyt » Fri Jan 25, 2008 2:19 pm

graybags wrote:Please tell me this isn't normal. My Wife's 2.0TT is as quick.
That's *definitely* not normal!

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CliveH
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RE: Re: Engine Rough at 2300rpm, Normal?

Post by CliveH » Fri Jan 25, 2008 3:34 pm

None of that sounds normal to me Graham.

Take it to a specialist - oh, I see you're in Oxfordshire - just pop down the road to MRC. Doug will tell you exactly what's wrong with it :thumbs:
Clive

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RS4 B7 phantom black saloon, mint, fully loaded, low mileage - FOR SALE!- http://www.rs246.com/index.php?name=PNp ... ic&t=88981
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graybags
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Post by graybags » Fri Jan 25, 2008 3:40 pm

Thank you both for the reassurance.

I was pretty sure it was wrong. I will go to MRC.

Cheers, Graham

skiwi
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Post by skiwi » Fri Jan 25, 2008 10:07 pm

are you sure there are no codes? it sounds like you have a misfire and the usual suspects for these events are plug wires, output coils or maf.

definitely take it to a good dealer and demand that they fix it. what you describe is not normal.

graybags
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Post by graybags » Sat Jan 26, 2008 12:03 am

It does feel exactly like a misfire – worse under load and higher revs.
Frustratingly, there are definitely no codes though.

I demonstrated the effect to a dealer today and was assured that it was normal.

Any recommendations of a dealer that really knows what a '6 should be like?

Gray

skiwi
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Post by skiwi » Sat Jan 26, 2008 8:14 am

1) not all misfires will throw codes.

2) change dealers.

3) for your own peace of mind, i suggest that you find another rs6 owner in your area (and they are some probably on this list) and compare vehicles.

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Gavc500
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Post by Gavc500 » Sat Jan 26, 2008 9:51 am

PM'd you
Ebony Black Avant with Black Optics, Silver Leather and Piano Black/ Full Milltek - 100 CPSI cats and non-resonated! TVR for the summer..... and SL55 AMG just for the pose!!

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CliveH
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Post by CliveH » Sat Jan 26, 2008 1:27 pm

What skiwi said :thumbs:

On #2, I assume you haven't got to see MRC yet?
Clive

S2 ABY coupe, S4 B5 saloon, S4 B6 avant
RS4 B7 phantom black saloon, mint, fully loaded, low mileage - FOR SALE!- http://www.rs246.com/index.php?name=PNp ... ic&t=88981
S8 D2 facelift, RS6 C5 saloon, both gone but not forgotten

graybags
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Post by graybags » Sat Jan 26, 2008 5:48 pm

Spoke to Doug this morning. Car's booked in this Thursday. As he quite rightly said, a dealer will just continue to change parts until they hit on the right bit – which could take ages.

Un-surprisingly, the rough running is much more noticeable now that I have finally got the DRC system sorted. Wow! What an improvement that makes.

Really anxious to get the engine fixed now. I've owned the car nearly two months already.

Thanks again everyone for the assistance.
Graham

MarkB
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Post by MarkB » Sat Jan 26, 2008 5:49 pm

Keep us all updated. It's good to hear what the result was... Thanks
Mark

graybags
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Post by graybags » Fri Feb 01, 2008 3:10 pm

Well now I really am confused.

According to a thorough health check (thanks to Doug), there is no evidence whatsoever of any misfiring from the engine. Fuel, lambda, airflow, timing, exhaust temp, etc., all normal.

But. . . there is a definitely a vibration coming from somewhere as the revs rise – particularly felt at around 2K. It is noticeable when driving and when in neutral it actually shakes the whole car.

Is this, perhaps, just normal for the V8?

It does seem to pick-up better now all the plugs are tighter though.

Concerned of Oxford.

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Rupert
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Post by Rupert » Fri Feb 01, 2008 5:10 pm

I'm no expert, but would worn engine mounts have anything to do with this?

http://rs246.com/index.php?name=PNphpBB ... nts#156439
golfather wrote:They use hydraulic mounts as opposed to rubber bushes to reduce engine vibration coming into the cabin.

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Rupert
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Re: Engine Rough at 2300rpm, Normal?

Post by Rupert » Fri Feb 01, 2008 5:12 pm

andyt wrote:
graybags wrote:Please tell me this isn't normal. My Wife's 2.0TT is as quick.
That's *definitely* not normal!
Sorry, I read the rest.
Nope, that's definitely not normal. Mine still makes me say "wow" from time to time and that wouldn't happen if it wasn't stupidly fast.

skiwi
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RE: Re: Engine Rough at 2300rpm, Normal?

Post by skiwi » Fri Feb 01, 2008 8:05 pm

my guess would be engine mounts. they are electronically controlled using a fluid damper system. this is supposed to go from soft (@idle) to hard @higer revs. worth a check. good luck getting to them.

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