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[mr s]

Hi Guys,

The performance on our Grand Cherokee has been getting worse and worse of late.  I've taken it to a local mechanic who believes that the catalytic converter has collapsed.  Unfortunately he cannot check by removing the cat as yet, apparrently it's held on by a very fragile clip that the local Jeep dealer doesn't have in stock.

I was wondering if anyone else has any experience of this and if anyone can advise anywhere I pick up a new cat for less than the £500 +VAT that the stealers have quoted?

The car is a 2002 2.7CRD.  Any advice on this would be greatly appreciated.

[Mike Pavelin]

If it's the clip that holds the front pipe to the turbo, it's a Mercedes Benz part and easy to get hold of from a Mercedes dealer if Jeep have none. Take it somewhere else. If it needs a cat, you probably won't get a cheap one for the 2.7 diesel though.

[mr s]

Thanks for the tip Mike.  This is the second mechanic I've taken the car to, the last one assured me that a new intake manifold would do the trick, 3 days and a hell of a lot of cash later it was exactly the same.

If I could pick your brains a little further?  I'm getting a fault code of P0243, loads of black smoke and an inability to climb a kerb.  Mech thinks that the inside of the cat has become disloged and is causing a blockage.  I know it's impossible to say for sure but would you agree that it's plausable?

TBH if the clip is so readily available at MB i might just take a look myself.

[greggmo]

if a cat is breaking down it will some times block the exhaust when under load. i will find out if i can get you a good price on a cat tomorrow.

[mr s]

Thanks greggmo for another speedy reply.  I'd really appreciate it if you could supply a price.  Really beginning to regret not going for a 4L now, just seen a cat on there for one priced about £60.  And the money spent on the manifold we didn't need would've gone a long way to funding an LPG conv too  :oops:

[Mike Pavelin]

P0243 is a turbo wastegate solenoid code. Might be a clue or could have been caused by messing about with the intake manifold.

[mr s]

Yeah, I looked the code up and found that.  I believe the thinking is that the restriction caused by the cat is causing overfueling.  This in turn is probably clogging the EGR valve & intake manifold & somehow causing the wastegate to get all confuddled.

My initial thought was whooshing noise + this fault code + no power = loss of boost pressure somewhere.  However mechanic tells me that he has disconnected pipe from intercooler to intake manifold & there's plenty of pressure there.

Though having said all that, having pressure in the cooler pipe doesn't rule out the possibility of it escaping via a badly fitted gasket on the new intake manifold does it?

I guess I'll continue to take a look at the cat anyway, can't hurt to rule it out.

[Mike Pavelin]

If the engine won't rev, it's probably in limp mode becauae of the fault. Until the fault cose is cleared it will remain like this.

[jonathanhann]

this sounds like a one of the boost pipes with a split, opening up and letting the pressure escape.
i work for mercedes benz and we see this every now and then. The engine still fuels as if its got boost, resulting in the black smoke but as there is insufficent boost the mixture is wrong.

Spend time yourself, carefully get someone to put the car under load and try and listen for the hissing or air gushing noise. could be the intercooler or pipes to it.

hope this helps.

jon

[mr s]

This is probably going to sound like a really silly question so i'll apologise in advance :-)

If so i think i know what the outcome will be.  It'll most likely just sit there and do nothing.

[greggmo]

when we say under load we mean uphill with your foot on the gas and making it work hard. i cant get you a cat for it from my usual cheap supplier. sorry.

[demonicwillow]

The black smoke is your first clue, not having experiance with diesel cats, I think its turbo pressure, if you have wooshing then turbo compressor air pressure is escaping, the engine is chucking in tons of fuel but not getting the required air hence the black smoke, see it all the time with the marine diesels, basically wot Jonathan said  

[Mike Pavelin]

If the wastegte is playing up (like the dtc says) you will get those symptoms

[Doodle]

I know that this is on my saab but i had it for about a year and was pretty sure that it wasnt performing like it should. It was checked out and i wasnt getting the boost that i should.

Had most things checked. The local saab specialist checked the blades etc on the turbo and found nothing wrong- they reckoned the cat was blocked or if it wasnt it was the rest of the exhaust.

they got a second hand cat in and trail replaced- as soon as i turned the car over and you could hear it instantly and when i drove it it was fantastic- perfomance was back.

basically the cat had broken down but the mesh at the back hadnt split so therefore no bits could come out.

I now have a jeepo and a quick car!  

[mr s]

Thanks for all the replies guys - I'm determined to get to the bottom of this.

OK, the cat now resides in the boot of the car, a visual inspection of it suggests no problems there    Car drives just about the same with or without the cat in place (just sounds more like a challenger tank now).  Mech now wondering bout getting the turbo checked over.  Some sort of variable vane profile thingumy that could have gotten stuck meaning no boost.

I've been told of a company (Euroturbos) who can put the thing on a bench test to diagnose any issues.  Think I'll give them a call & see if we can get it booked in.  Probably best to see if the wastegate tested at the same time to eliminate it.