I've tried to search the forums but if I am double posting please could you point me in the right direction...

I have a 2006 4.2 Supercharger, that ran great after I fixed both the alternator and the supercharger coolant pump (inc checking direction, that inevitably was wrong with info from here) within the first year of owning.

Everything was great and I was loving the power, comfort, ride etc etc. (ignoring the intermittent air sus fault yet to deal with)

Until 2 days ago

My RR feels like and sounds like its somehow throwing away the compressed air from the supercharger. It pulls ok now but not half what it used to be. In the upper range of rev range it sounds like the air and whistling sounds are escaping behind the passengers side (its right hand drive) of the dash with no real pull after 4000rpm at all. I cant recreate the sound or fault stationary without the engine under 'strain', and i don't fancy the hand break being that good or wrecking a gearbox.

Ive had the interior air filter out and the lid of the engine off and I cant see any splits in any seals around the supercharger etc.

Preston Range Rover havent been that helpful (still waiting for a call back...) and I would rather look myself after one of the nice RR mechanics over in Burnley had a quick listen to see if I could get home etc but thought it could be a belt (even though it sound like whoosing air and supercharger wine (proper technical description)

If anyone has ever had a similar problem Id love to know what to do next...

I havent yet got a fault code reader but at this rate will get one next week

No fault lights on dash and no error messages either - just hope someone on here has had similar to deal with (and that the damage isnt too bad...)

Sorry to hear you're having some issues. Not able to help you unfortunately, based on the info sofar.

Does the belt sound like it may be slipping ?

Have you checked the MAF sensor (just after the filter in the inlet tube, two torx and it's out). Give it a good clean with carb or injector cleaner just in case.

Other possibility could be the MAP sensor (back of the supercharger if I remember correctly), they have been known to fail. Maybe it is giving wrong readings to the ECU making the ECU underfuel.

How is the engine running apart from the powerloss ?? Smooth ?? or sometimes a bit rough ??

Another option is of course that the gasket between the supercharger and inlet manifold is leaking or the supercharger has come loose (first I ever heard of). Just take the cover of and see if the SC is bolted down well.

Have a look at the air inlet tube from filter to SC to make sure it is all tight and no cracks/holes in the tube.

Could also be fuel system related, filter clogging up (it's in the tank unfortunately, so remove rear seat cushion and open up tank on driver side).

Are you running into problems around 1/4 tank ?? Could indicate fueling issues as well, the pump can't get it over the hump anymore.

I replaced my pump and filter with a new one on my 4.2 as I was having some issues as well and Kingpleb found a brand new pump for 50 GBP so I just put it on, had the fuel system cleaned including the entire inlet manifold and injectors. Plus ECU update and after that it ran brilliantly. Not sure what was the problem since I had it all done in one go.

That's all I can come up with now. MY 2010 5.0 SC Galway green and sand interior!!
Have the Faultmate MSV2 Extreme to be tinkering with the settings etc. !!

Cheers for the reply ebajema - it sounds more like different pressures of air escaping at different revs, and not a squeal of slipping belt. Does the 4.2 have an air dump if it is under fuelling to stop it from running really lean?

The car runs smooth, except the very occasional clunky gear change, idles correctly and everything else is nice and quiet.

It's the same with half a tank, 1/4 tank etc

I'll give the AF sense a clean today (although a while back when I did the SC coolant pump and the connector hadn't say correctly all sorts of errors ensue, so it must be doing something correct)

were there any fuel pressure related fault codes when you did your filter etc
Did yours sound the same on under fuel? (Like an air bed leaking air / faster with more power / less at lower revs etc)

Thanks again

i would guess its a small split/hole in a pipe somewhere which gets bigger under strain ... - .- -.




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Stan you could be right. That is what I meant with the SC being loose or the gasket leaking because that is where the air is pressurized so it would go out. So air is leaving after being measured by the MAF and that makes the mixture more rich.

The inlet side (between filter and SC) is in suction (below ambient pressure since the SC is sucking air in. So after the MAF measured the amount of air going in, additional air is added so the engine starts running leaner.

Another option is a leak in around the inlet manifold, again air being pushed out before getting into the combustion chamber so more petrol going in than there is air for the perfect mix i.e. richer.

As for my problems, I was suffering from a raft of issues at the time including the gearbox solenoid problem and the gearbox and engine oil heat exchangers bursting.

So we did a lot of work. I did have lean mixture issues before it all started and replaced the lambda sensors, didn't change anything until I reflashed the ECU with the latest software, no more issues after that. But by that time the entire fuel system, inlet tract were cleaned and the new pump and filter installed as well .

So sorry, can't help you with the specifics but it would help to get a diagnostic system (IID BT I'd suggest) and clear all your faults as there is likely to be a raft of historical faults. Then drive and check for faults again. I can't remember for sure but I think there is a fuel pressure reading in there and there is also a low fuel pressure code if I remember correctly. And definitely try to get the ECU of the motor management reflashed with the latest software so you know that is at least sorted.

Replace the fuel filter itself anyway and check the old one and tank for dirt. My tank was also cleaned and made spotless at the time. But mine was in Nigeria so I don't know what got into the tank and what quality fuel you're getting. Nigeria is notorious for getting dodgy fuel with all kinds of "extraordinary additives" . So not really comparable with the UK (I hope !!).

With the IID you can also read the MAF and MAP values and whether they generate out of range issues (which could be air leaks or sensor issues). Check all the connectors as well as their wiring.

I don't know of any pressure relief, well I can't remember to be honest as I worked on it a LONG time ago.

The 5.0 SC is running flawlessly (although I'm not the one driving it) it sailed through the MOT again, brake hoses recall done and corrossion check done. So I'm not getting any more fault finding experience with it THank goodness !!

Good luck with the search and please keep us posted  MY 2010 5.0 SC Galway green and sand interior!!
Have the Faultmate MSV2 Extreme to be tinkering with the settings etc. !!

I had a similar thing with my 4.2 which turned out to be a clogged air filter and under high rpm was sucking in the pipe between the air filter and inlet. Might just be worth checking.
Stewart.

stan wrote:

i would guess its a small split/hole in a pipe somewhere which gets bigger under strain

cheers all - i honestly didnt expect so many replies, as well as international, or any help with a boring fault.... I suppose it's about lack of power, one of the things we all buy RR for.

Ive had a look at clips Royston, but there only seems to be one on the MAF sensor (cleaned this morn ebajema) and the rest is all bolted unlike the turbos with pipes and jclips everywhere (as far as i can see from the manual), its seated correctly at the back and i cant feel air leaking while its being revved.

It didnt seem to do it while 'cold' well warm but not fully warm as im not the brutal to drive so hard cold, as it gets warmer it gets worse, but could just be coincidence. I thought it could have been a hole in the seal on the supercharger Stan, that as the engine warms makes the rubber more pliable, but I really didnt want it to be that as the seals seem to be impossible to get from anywhere else than Jag or RR in the uk and look a bit of a pain to fix (although at least at the top of engine)

Im going to check the air filter as soon as I finish typing this Stewart, its been in and out a few times and could be chocking the engine, seems logical, the MAF would be getting less air, puts in less fuel to compensate, doesnt run rough etc and all the noises are from that side of the car and the RPM would still spool the supercharger and it would be trying to suck through the smallest of gaps etc. If its the air filter ill be one happy guy, and in need of getting a few drinks in... I would never have thought about that.

Its a shame I dont have a power take off, I could have run a dummy load and made the engine work hard stationary like doing a generator load test

Back soon with update


Need to buy a FFRR sticker as well

WOW...

Well this is awkward .... so just had the air filter out, given it a bang well away from car, half a ton of dust and a farmers field full of hey later... tipped out little bits from bottom of the air intake, resettled everything including the rubber in wing... replaced the cleaner air filter and the car is alive!!!

just taken out on a 'test run', (not wanting to get into trouble, well away from people and no schools open at this time ) but now its pulling from 30 to normal motorway speeds how it used to (if not better) but need to take it out somewhere other than an A road to check properly as I ran out space, couple of other cars / police chopper out and about and not really up for giving us all a crap rep or getting points on my miraculously clean licence...

Ive not had it long enough yet to think about doing a service as I was told everything had been done (going to check SH when I get home) New air intake filter tomorrow asap and will be doing the lot (inc pollen etc) then going to do plugs oil etc...

One happy S/C owner, for now....

Thank you so much Stewart honestly the last thing it sounded like or that i could have thought , I feel like a muppet but will now frequent here loads to see who I can help in the future....

Thanks FFRR