Loud knocking noise when under load

[StevenB]

Hi,

Looking for advise here please.

I have a loud knocking noise. Seems more combustion than mechanical and its a very loud clatter ! Much more than normal diesel clatter

Car is a vrs tdi and only 3 weeks old and 1850 miles.

Could it be coincidence that this appeared about 10 miles after filling up

No alarms are up on the dash.

I can Rev through the clatter and things settle down and appear normal.

No drop off in performance.

Revving at a standstill and bonnet open, it is just audible when revved. Happens worst when initial accelerating and the engine comes under load. Noise is not linked to revs which is why I'm thinking it's not mechanical.

Have considered calling the assist line to get someone out as I have to go to Heathrow twice next week !

Have done about 40 miles today and cold or warm makes no difference...

Steve

[Shermo]

Where did you fill up? I've noticed mine be a lot grumblier when filling up at Sainsbury's and now try and fill up at Shell only

[StevenB]

Tesco. But in fairness, it's used fuel from there since new.

I may try and stick some shell + diesel in but at the moment, the gauge is still on full.

[CJSVRS]

Mine has done this a couple of times. Sounds like a petrol engine pinking badly under load. The first time it had what felt like a misfire too. Dealer checked it a could find nothing. It happened in first 1000 miles after filling up at a French Shell garage. The second time it was my normal Tesco fuel.

[StevenB]

Yes, like a loud petrol engine pinking.

I've got skoda assist coming out to have a look.

Also phoned Tesco and they have started proceedings for contaminated fuel ! The lady on the phone wouldn't comment when I asked her if they had a known fuel problem from the station I filled up at!

In 20yrs of owning a diesel never had this before.

Steve

[StevenB]

The guy from Skoda assist was very helpful and confirmed contaminated fuel but not a show stopper so to speak and the noise was the injectors.

Went for a little drive on Sunday and managed to get about 15lts of Shell nitro+ into the tank and the difference within 3 miles was like having a different engine under the bonnet !

Not sure what to learn from this as Tesco mailed me today to say I was the only person to raise a concern and therefore nothing more they could do.

Looks like She'll will be getting more of my business..

Steve.

[Neily03]

Filled mine up at Tesco on Friday, it's running exactly the same as it does on Shell's diesel.  Any fuel can be contaminated, considering it comes from only a handful of refineries, there's nothing to say the stuff you buy from your local shell isn't from the same tanker that just topped up the local tesco....  But i'm not getting into a fuel debated here.

[StevenB]

I agree and take your point.

To be honest, we shop at Tesco and we normally get at least a tankfull with the 20p a lt saving per month which is a cracking deal..

[blahde2]

I agree and take your point.

To be honest, we shop at Tesco and we normally get at least a tankfull with the 20p a lt saving per month which is a cracking deal..

I found that my VRS hated any fuel of the supermarket variety....more the DPF didn't like it one bit. Normal Shell or BP diesel was fine but put a tank of TESCO, asda or S'burys in and every 100mile or so I would need to actively assist a DPF regen cycle.

I see the 20p saving and pine for it, but don't want to risk the DPF dying as that's £1200 + labour. However if your diesel runs just fine on it, then I'd keep using it as 20p is still 20p and that's an epic saving over a year!

[Matt Pez]

Based on the fact that I'm getting at least an extra 50 miles from a tank of fuel running on regular Shell diesel compared to Tesco, that equates to an average saving of £5.50 per tank, or 12 pence per litre based on 45 litre fill up. I won't be going back to Tesco for diesel but we still use Tesco for regular unleaded for SWMBOs TSI as not noticed any significant difference using Shell unleaded, so SWMBO gets her monthly 20 ppl on one fill up while I get about £20 per month saving sticking to Shell diesel.

[themanwithnoaim]

Under flatout acceleration with the TC flashing like mad, I get a knocking noise but I kinda figure thats just the drive shafts complaining. Could be wrong on several levels though.

[StevenB]

I used to fill the Scoob with the 99 Ron stuff and had no trouble with that.

My Mrs has my old ST Mondeo tdi and that has never grumbled with Tesco fuel.

Not sure what to conclude..could have been a bad lot or the VRS is more fussy on fuel ?

We shall see...

Steve

[Yogi-Bear]

I used Shell vPower Max expensive rip-off diesel for the first 1,000 miles in my new vRS... and then I switched to Tesco cheapy diesel, and have now done just over 2,000 miles.

 

In all honesty, I haven't noticed any difference, and the economy has been getting better - but I'm putting that down to the car running in rather than Tesco diesel being better than Shell.

 

So, in conclusion, given the tolerances that the engines need to work to (see other thread about 92 RON fuel in Egypt), I don't think any of the fuels we have in this country should make any massive difference at all... and certainly shouldn't cause the engine any problems whatsoever.

[Matt Pez]

I used Shell vPower Max expensive rip-off diesel for the first 1,000 miles in my new vRS... and then I switched to Tesco cheapy diesel, and have now done just over 2,000 miles.

 

In all honesty, I haven't noticed any difference, and the economy has been getting better - but I'm putting that down to the car running in rather than Tesco diesel being better than Shell.

 

So, in conclusion, given the tolerances that the engines need to work to (see other thread about 92 RON fuel in Egypt), I don't think any of the fuels we have in this country should make any massive difference at all... and certainly shouldn't cause the engine any problems whatsoever.

V Power is defo not worth the extra, makes no difference over standard Shell Diesel as far as I can tell, but in my experience standard Shell diesel gives better economy than supermarket diesel.  I base my comments in post #10 having used supermarket fuel continuously for several weeks, then switching to Shell.  Not done a long term test on unleaded but did not notice any significant difference between Shell unleaded and supermarket unleaded to justify losing the 20p discount we get filing up SWMBOs TSI at Tesco as she only needs one fill up per month.

[andyvee]

My PD140 used to get 50 miles less per tank on Tesco diesel. Filled up at Morrison's once and it ran like a dog on that tankfull.

I just stick to standard Shell diesel.

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[Crogers]

I notice a difference with 99 over 95, and if you shop at Tesco the 20p you save is more than wiped out by the massive cost they charge for.. well everything, but thats a conversation for another time. 

 

I think its worth spending the extra on branded fuel I put 99 in mine and she uses normal, but she won't buy fuel from a supermarket anymore, says its not as good as Shell/BP.

 

I would say I get better economy from 99 and the engine seems to have slightly more responsive, but thats my 5 pence!