It sounds like you need the IID or Faultmate so you can have a look at fault codes, values etc. It sounds like something that would show up immediately on the diagnostics.

If I understand you correctly, the car is becoming slower and slower, is that correct ??? If so, the issue is likely to leave you stranded or do serious engine damage possibly. Not sure if it is wise to stop using it until you know what is going on.

If there is a false air issue, it could be anywhere and difficult to see. The intake itself could have a crack somewhere almost invisible, if some bolt or nut has come loose/off there could be air going into or out off the inlet tract. I'd suggest to get a smoke test done.

If you have the cover off anyway, you could try to use soapy water and see if you notice any bubbles i.e. air leaking out of the inlet tract. Also have a look for loose bolts nuts etc.

Have you checked in air filter, MAF sensor hose already ??? MY 2010 5.0 SC Galway green and sand interior!!
Have the Faultmate MSV2 Extreme to be tinkering with the settings etc. !!

Yes, checked air filter and MAF hose. Also checked and no codes in the car at all and no warning lights on the dash either.

I would have thought if it was a leaking manifold etc...then it would more than likely do it all the time and there would be evidence of a leak and it would be more obvious. Going to try and check the exhaust system as if partially blocked it could explain why the air noise only occurs under WOT and it could be coming back out of the exhaust.

It Is a weird noise though...

cheers Alex

2018 Skoda Kodiaq vRS
2009 Caterham Supersport Race car
2007 M5 Touring
2005 Range Rover Vogue SE Supercharged
2004 SL55 AMG

I'm starting to wonder if it could be the supercharger. Have you ever changed the oil of the supercharger ?? Maybe it is getting more resistance and therefore not working properly but without triggering any faults, just less air going in........... Should trigger faults I'd expect though. MY 2010 5.0 SC Galway green and sand interior!!
Have the Faultmate MSV2 Extreme to be tinkering with the settings etc. !!

Never been changed and we have had the car from 2.5 years old and 27,000 miles to today with 100,700 miles on it.

It is a thought that we have had, the belt and pulley seem ok and not seized or anything, but with the age and mileage of the car if the supercharger is opened up then there will be an amount of wear on it anyway.

Going to check the exhaust side today/tomorrow and see what that reveals. If not, probably going to find an indy who is good with the 4.2 and aware of any issues before giving it to LR who don't see very many of them so are never quite sure when they look at it.

cheers Alex

2018 Skoda Kodiaq vRS
2009 Caterham Supersport Race car
2007 M5 Touring
2005 Range Rover Vogue SE Supercharged
2004 SL55 AMG

The SC engines seem to be remarkably reliable, same as the NA Jag V8s so it is hard to find out what is going on with yours because there is little history of failure. Same goes for the ZF gearboxes, when mine played up there was very little information on failure despite that box being in many different model cars.

Lets hope it is something simple and cheap to repair !!! MY 2010 5.0 SC Galway green and sand interior!!
Have the Faultmate MSV2 Extreme to be tinkering with the settings etc. !!

I'm beginning to think it is more likely the supercharger has failed or is starting to fail at the moment so will make some phone calls to get a rough guide, but I will still get a camera stuck down the exhaust to check the cats.

My gearbox isn't great either  Alex

2018 Skoda Kodiaq vRS
2009 Caterham Supersport Race car
2007 M5 Touring
2005 Range Rover Vogue SE Supercharged
2004 SL55 AMG

So, don't believe the exhaust is blocked - but have not checked.

Have spoken to an LR specialist who said to check pipes to and from the throttle body and the throttle body itself as when he worked for LR, he replaced some pipes. Trouble is, they only look after two SC 4.2's as they say they are few and far between and this is what LR say to me. Have checked vacuum hoses again and made sure that they hold a vacuum and they do, so at the moment they appear to be ok.

Next step is to maybe remove the top of the supercharger and have a look inside. Has anyone ever done this? How easy is it?
Looks like there is a company called Powerhouse who may be able to refurbish the supercharger if that was the fault.

Thanks Alex

2018 Skoda Kodiaq vRS
2009 Caterham Supersport Race car
2007 M5 Touring
2005 Range Rover Vogue SE Supercharged
2004 SL55 AMG

If you speak to Lawton at Powerhouse he is very knowledgeable about S/C Jags and apparently has recently bought himself a L322 S/C. The M112 S/C snout bearings and rear bearings are replaceable but unfortunately not the centre bearings, but to be fair it would be a very definite bearing whine if the bearings are at fault............I know because mine need replacing!!
If you have the engine cover of then undo the allen headed socket grubscrew at the front of the supercharger and see if any oil seeps out. My advice is that you don't take it right out because it is very easy to drop it down the front of the engine.
The bearings and service kit are available as a DIY item but if you want to fit the +10% pulley upgrade then I suggest that you have the snout machined properly.....Powerhouse can do this for you apparently.
I'm taking mine apart to do exactly this after the tax expires end of August.
Cheers,
Ken 55 S/C L322 Zambesi Silver.....GONE!!
56 S/C L322 Java Black......surviving at present...just!
04 N/A 4.2 V8 S Type Jag
1961 reg 3.5 V8 Bowler Tomcat.....Sold
Numerous Classic (rusty!?!) Minis

So, my local LR dealer have the car. They can hear the noise, have checked all the pipes I have checked and checked for fault codes - none stored. Have sent video of it again, at the moment they have drawn a blank as to a definite fault.

The issue is going to be having an educated guess as to what to start taking apart first to try and find the issue.

I suppose if it can't be fixed for a reasonable cost, then probably time to change the car  Alex

2018 Skoda Kodiaq vRS
2009 Caterham Supersport Race car
2007 M5 Touring
2005 Range Rover Vogue SE Supercharged
2004 SL55 AMG

It is interesting that there are no fault codes stored, that means that all parameters measured are within their normal range. I'm starting to wonder if there is a fuel restriction issue although I'd expect a fuel pressure fault or the potentio meter on the accelerator failing maybe. In the sense that the ECU gets told to not go as fast as you would like, so you are thinking that you are at full throttle but the potentiometer is actually only giving part throttle......... That is unlikely to show up on the fault code list but it may be possible to look at the live data to see if there is something showing there. MY 2010 5.0 SC Galway green and sand interior!!
Have the Faultmate MSV2 Extreme to be tinkering with the settings etc. !!

Smoke test has been done which is showing no leaks.

I am using a lot more fuel. I normally average around 360 miles to a tank and only got 230 miles to this tank before giving it to LR on the 7th July. Even accounting for putting my foot down five or six times to test the noise and power it is still using far more than normal. Average fuel consumption dropped by about 0.4mpg on the computer.

cheers Alex

2018 Skoda Kodiaq vRS
2009 Caterham Supersport Race car
2007 M5 Touring
2005 Range Rover Vogue SE Supercharged
2004 SL55 AMG

Hi zarnd,

I've listened to your video clip another 3 times today and your noise is nothing like mine, but to be fair I'm really only hearing road noise, not induction/air escaping under pressure. My problem sounds definitely like bearings but I won't be stripping my S/C down until next week now, but please go to this picture kindly supplied by forum member "kyle h." back in Nov 2016.

http://www.fullfatrr.com/gallery/albums/us...ge~14.jpeg

I you look at the picture now the central alloy intake hose has been removed so you can see the two black gaskets between the output air housing of the charger and the water cooled/heated inlet manifolds. It might possibly be one of these leaking or even the top housing to the top of the charger seal if it is definitely an air under pressure noise you are experiencing. But to be fair I am just clutching at straws trying to help you.
Cheers,
Ken 55 S/C L322 Zambesi Silver.....GONE!!
56 S/C L322 Java Black......surviving at present...just!
04 N/A 4.2 V8 S Type Jag
1961 reg 3.5 V8 Bowler Tomcat.....Sold
Numerous Classic (rusty!?!) Minis

Thanks for that, smoke test and hoses checked and nothing found as of yet.

The noise sounds like it is coming from behind the glovebox and not the front of the car which is even stranger... Alex

2018 Skoda Kodiaq vRS
2009 Caterham Supersport Race car
2007 M5 Touring
2005 Range Rover Vogue SE Supercharged
2004 SL55 AMG

To be honest that is where my noise is more prominent as well. To the extent that the Wife will actually cover her ears because it is quite high pitched and engine rev related, bearing (ish) noise. She now won't travel in the car!!
I just assumed that there was less sound proofing there because of the glove box, hence more sound transfer than through the dash area in front of me.
I bought a new (old stock) Charger from the bay of thieves! It's now on its way to me from Powerhouse after being checked over by them and having a 10% pulley fitted !!
I'm desperately hoping this will sort my problem, but unfortunately it seems not yours.
Good luck. 55 S/C L322 Zambesi Silver.....GONE!!
56 S/C L322 Java Black......surviving at present...just!
04 N/A 4.2 V8 S Type Jag
1961 reg 3.5 V8 Bowler Tomcat.....Sold
Numerous Classic (rusty!?!) Minis

I'm wondering if the increased fuel consumption is pointing towards the MAP or MAF being way out of whack but I would expect the exhaust system lambda sensors to pick up on mixture not being right, too rich. The increase in fuel consumption is pretty high and that indicates something quite substantial amiss but that it doesn't throw up any codes is strange..............

If the mixture is right (and considering no faults it should be) then the extra fuel is either leaking out somewhere (return line to the tank ??).

There is no fuel pressure fault, so the lack of power is unlikely to be fuel starvation

If the SC is doing what it is supposed to do, then fuel will be going in accordingly and all would be OK, if the SC is not pushing enough air in (the MAP would notice that and the fuel amount will be adjusted accordingly) fuel consumption would be sort of normal.

I'm starting to wonder if there is a gearbox issue that is causing too much powerloss while the engine (and SC) are fine......... Maybe worth asking RRPhil if he has any idea about what could be wrong with the gearbox that doesn't throw a fault, makes this type of noise and reduces poweroutput to the wheels................... I feel like I'm clutching at straws now..... MY 2010 5.0 SC Galway green and sand interior!!
Have the Faultmate MSV2 Extreme to be tinkering with the settings etc. !!