Mitsubishi GDI Carbon build-up

Honest John Back Room » Technical matters
View Threaded
Sat 11 Feb 2006 17:33
Mitsubishi GDI Carbon build-up - Fat Andy
This is my first posting although I have been reading for a while.
I have a 2000 Mitsubishi Space Wagon 2.4GDI with 37000 on the clock. It has always been serviced by the main dealer, including the optional oil flush and fuel additive. I have always used 98 Oct petrol as well. Despite this I have started to notice all the signs of carbon build up within the engine.(rough running, poor starting, occasional tappet noise at low revs) A quick look at mitsubushi forums shows that almost everyone with a GDI engine (some volvo's too)has the smae problem, yet Mitsubishi only advise a strip down and clean up at approx £600, or replacement throttle body at much the same price. Is this acceptible in a low mileage, well cared for car. Mitsubishi state that the UK petrol is not high enough quality, but they sold the car in the UK and must have known about the petrol available. What next?
Reply | Report as offensive | Link
Sat 11 Feb 2006 19:03
Mitsubishi GDI Carbon build-up - Aprilia
This is a very well known problem with direct-injection petrol engines. The engine can be de-coked in situ by using crushed walnut shell blasting - this is much cheaper than stripping the engine. May need new throttle body - BBA-reman sell these for about £450 IIRC.
Reply | Report as offensive | Link
Sun 12 Feb 2006 07:22
Mitsubishi GDI Carbon build-up - storme
and how slowly do you drive??? do you ever have a quick blast up the motorway???


i wonder if an italian tune would help you???
maybe a blast up the motorway every now and then??

thats going fast in all gears...not just doing 70 in top gear...red line it a bit
--
www.storme.co.uk
Reply | Report as offensive | Link
Sun 12 Feb 2006 19:14
Mitsubishi GDI Carbon build-up - Fat Andy
Thanks for the advice storme. I have redlined it once or twice and as expected every one behind me dissapears in a cloud of smoke. The trouble is finding a place to redline it in south London!!

The car does get a lot of town use and longer trips very occasionally

Is it worth using some additives in the fuel as well as using the Optimax type fuels?
Reply | Report as offensive | Link
Sun 12 Feb 2006 19:23
Mitsubishi GDI Carbon build-up - bell boy
thats interesting Aprilia please enlighten?(not the bba bit i know about them :))
--
\"a little man in a big world/\"
Reply | Report as offensive | Link
Sun 12 Feb 2006 20:15
Mitsubishi GDI Carbon build-up - Aprilia
GDi injects petrol straight into the cylinder. To get good economy they use up to 48% EGR (exhaust gas recirculation). Hot gas flows into inlet manifold where it meets oil mist coming from the crankcase venting systems (via PCV valve). The result is that the oil mist carbonises on the intake manifold and valves - rock hard stuff.
THis can be reomved by taking off inlet manifold and blasting it (and back of valves) clean with crushed walnut shell abrasive. Dealer also use some solution called 'Shuma' (I think??) that helps dissolve the carbon. Takes a couple of hours to do the job. Volvos suffer just the same.

I bad cases the throttle body also gets carboned up.

Mitsu (UK) reckon you should only use Shell Helix fully synth oil and 97+ octane petrol. Also use Mitsu injector cleaner additive (Part no. MZ380226 - I just looked it up for you!).

Better still, don't buy direct injection petrol engines. As usual, stick with the tried and tested if spending your own money.
Reply | Report as offensive | Link
Sun 12 Feb 2006 20:55
Mitsubishi GDI Carbon build-up - bell boy
thank you, never heard of that but always willing to learn.
--
\"a little man in a big world/\"
Reply | Report as offensive | Link
Mon 13 Feb 2006 20:52
Mitsubishi GDI Carbon build-up - gerryt
Just checked the handbook for my 2001 1.8GDI Carisma. Says 95RON or higher in there so I don't see how mitsubishi aren't liable for carbon build up if the vehicle has been serviced properly.
Reply | Report as offensive | Link
Mon 13 Feb 2006 21:09
Mitsubishi GDI Carbon build-up - Aprilia
Well, that's one to argue with Mistu. Like I said, best to avoid new technology on cars, unless you fancy paying for part of the development programme.
Reply | Report as offensive | Link
Mon 13 Feb 2006 23:29
Mitsubishi GDI Carbon build-up - shadow.saw
try using some 10k boost also if you know your way round an engine pour some injector cleaner down the inlet also to stop it happening again buy some fuel treatment which will stop it happening agian or even some octane booster
Reply | Report as offensive | Link
Sun 24 Aug 2014 15:32
Mitsubishi GDI Carbon build-up - Chopper2017

Carbon build up issues are no more with the aid of a very simple service with hydrogen technology.

I had mine done, it took 30 mins and she ran like a dream.

Cost £70.00 to remove the carbon build up and left my car with a great increase in performance, power and fuel efficiency.

It ran quieter and smoother.

It cleans the carbon from the air intake right through to the exhaust including turbo's, valves, combustion chamber, inlet manifold etc,DPF(if not too far gone), EGR and CATs...

Very effective, cheap and non invasive service.

Reply | Report as offensive | Link
Sun 14 Sep 2014 17:09
Mitsubishi GDI Carbon build-up - Dave - Northampton

What is this "service with hydrogen technology" Chopper2017? I've searched online but I just keep finding content about cars that use hydrogen as a fuel. Can you give a link to a page that explains it?

Reply | Report as offensive | Link
Sun 14 Sep 2014 22:44
Mitsubishi GDI Carbon build-up - galileo

What is this "service with hydrogen technology" Chopper2017? I've searched online but I just keep finding content about cars that use hydrogen as a fuel. Can you give a link to a page that explains it?

I'd also be interested to know how "hydrogen" is supposed to dissolve carbon. Carbon is notoriously difficult to dissolve, concentrated hot sulphuric or nitric acid will do the trick, but also dissolves your engine.

Pure oxygen fed onto hot carbon will burn it off but again not good for engine parts.

The electrodes in steel-making furnaces are made from carbon - operate at 3000 Centigrade at the hot end but only erode slowly.

Hydrogen does not readily combine with carbon to form methane or similar gases, I don't see how it could do this in engines, turbos, DPFs etc.

I do hope the OP can provide details of the provider of his magic service.

Reply | Report as offensive | Link
Mon 15 Sep 2014 00:01
Mitsubishi GDI Carbon build-up - Xena
It might be worth checking out a decoke system called TerraClean. I've not used it myself, but there is quite a bit of discussion about it on the web. Have a Google.
Reply | Report as offensive | Link

Looking for a garage you can trust? Honest John's Good Garage Guide has thousands of reader recommended garages, plus how-to guides and tips on servicing.

The Good Garage Guide