2.4 GDi Engine, noisy tappets and perfomance issue - waue1978
Does anybody have any experience with the aforementioned engine? Specifically, the 2.4 GDi Space Wagon.

Have recently bought a manual UK model with 98k, fairly good history - cambelt changed at 92k - but it seems to be displaying some strange habits.

Have looked at a couple of forums & there seem to be a few issues with excessive carbon build up which can destroy throttle bodies & noisy tappets.

Mine seems to run fine, but it does have the tapping noise & (every now & again) a bit of a hesitancy under hard acceleration. The noisy tappets seem to be heard more often than not at the mo, but the hesitancy really is an occasional thing & has only happened thus far under full throttle acceleration, going uphill & 2 out of 3 times was on a relatively cold engine. It's almost like the poor thing is coughing & spluttering! 10 seconds later & I can put my foot to the floor & she picks up cleanly.

The idle speed ranges from 1500rpm at cold start up to approx 700rpm when warm. Revs occasionally drop to 500 when pulling up at junctions, but haven't had it stall.

The car itself seems to be well looked after, but the previous owner had only used it for the same 2 mile trip to & from work over the past few weeks.

All I've done so far is put a bottle of STP injector cleaner in with a 3rd of a tank & 2 days later filled with Super Unleaded, but it did it again this morning. At the moment I'm under the impression that a good service (accompanied with a good engine flush on the oil change) & perhaps some 10k boost or other Decoking agent may solve the problem, but don't want to spend out on that & later find that the throttle bodies needed replacing. By the same measure, I don't want to spend £2-300 getting the throttle bodies replaced only to find that a service would've done the trick.

Is there anybody with enough experience on these to give a relatively educated opinion on the best course to follow?


Edited by Pugugly {P} on 16/12/2007 at 11:54

2.4 GDi Engine, noisy tappets and perfomance issue - jc2
A fast,hard drive will probably work better than all the chemicals especially if it's been used for 2 m. drives.
2.4 GDi Engine, noisy tappets and perfomance issue - Aprilia
Adding a decoking agent to the fuel will have no effect on the carbon build-up. The carbon builds up in the intake area and orginates from recirculated gases - because no fuel enters this area the deposits are not washed away. No fuel additive can enter this area so don't waste your money on it.

Best thing would be to visually inspect for carbon deposits (this may need some dismantling or use of a endoscope). Mitsubishi do their carbon cleaning agent which can be sprayed into the inlet area.
2.4 GDi Engine, noisy tappets and perfomance issue - waue1978
What you're saying makes a lot of sense - its just too cold to be outside dismantling & to be honest, I really don't know my way around a GDi engine well enough to chance it at the mo.

Remembered a product that was publicised a few years ago called 10k Boost, & I've just found that it's still available. Spray it into the air intake & it clears out the carbon build up.

Would this be a wise investment or could it potentially cause more problems than it would solve?
2.4 GDi Engine, noisy tappets and perfomance issue - Tim Allcott
My mother in law has one of these so I get to drive it quite regularly. The hesitation might be due to the fact that the engine is (I believe) always running as lean as it can be: and I wonder whether, sometimes, it tries just a little too hard. I find it slightly annoying, but not as annoying as the vehicles thirst!
2.4 GDi Engine, noisy tappets and perfomance issue - waue1978
Well, she had a full service yesterday. All filters changed, plugs were left though as the mechanic said they were in good condition & were platinum plugs too. They ran some super duper cleaner through the system & he even managed to give the throttle bodies a bit of a clean, but he did comment that they weren't too bad anyway.

However, when I was driving him back to the garage I managed to get the car to do its spluttery thing again. He's suggested that it may be the potentiometer on the throttle bodies that's causing it & that a new set may solve it (wasn't 100% sure though).

I then spoke to a company called Guy Rogers that will rebuild mine for £200 + VAT, but the fellow on the phone said that if the problem is intermittent, it may not show up on their bench test. They could still do the rebuild, but it may turn out that the problem wasn't with the throttle bodies. His best advice was to find somebody with the correct equipment to diagnose the fault first (but admitted that Mitsubishi dealers may not be the best option).

Something I forgot to mention in the first post - once in a while I can turn the key to start the car & get nothing. No turnover, no tick, just nothing. If I then switch off & start again it will start as normal. Could this be related or would it seem that I have got myself a "Friday Car"?

2.4 GDi Engine, noisy tappets and perfomance issue - Screwloose

Don't worry; these were only built on Fridays....

This sounds exactly like the problem Aprilia suggests; manifold clogged solid with carbon and one or more of the inlet valves intermittently sticking open - hence the tappet sounds.

Frankly; I've never had much luck with spray cleaner. To do the job properly is head-off, inlet guides modified and the manifold blast-cleaned. A can of spray might be worthwhile as a temporary test though.

2.4 GDi Engine, noisy tappets and perfomance issue - waue1978
Can anybody reccommend an expert in the SP10 area that I could take the car to?
2.4 GDi Engine, noisy tappets and perfomance issue - mr pembroke

hiya, i have been experiencin the same sort of problems with my 2.4 gdi spacewagon. it sometimes struggles on tick over, and it missfires occasionaly which causes it to lack in power. i have had a diagonosis check done and was told it was a fault on the cam belt but the previous owner had it replaced, another garage said it was a build up of carbon in the throttle body and that it neede decoked. after reading different forums and seein that quite a few pple have the same problems and how they resolve it so i had a go.

I removed the throttle body and srubbed inside the plastic housing with a little petrol and a bottle brush, then sprayed 3/4 of carbareta cleaner inside. cleaned the butterfly valve and put it back together. the only problem is once i put it all back together it did take a few attempts to start but once she fired she was idling perfect.

I took her for a drive and coudlnt believe how much this could change the performance...she flys like s*** now!!!

im just hopin this has solved the problem and i dont need to spend hundreds of pounds on a decoke!! but i recon this needs to be done every so often due to the build up of carbon that they suffer from. hope this is of some help to you guys and will keep u posted on any change in my car.

2.4 GDi Engine, noisy tappets and perfomance issue - injection doc
Coked up inlet valves can cause sticking which in turn makes the tappets noisey and also coked up inlet valves can cause hesitation.
I have seen restricted oil pick up strainers in the sump cause intermitant tappet noise!
There are a couple of methods of cleaning these without removing cylinder heads. I have done hundreds as I used to specialise in this method when fuels were very poor quality! I used a sand blaster with " walnut husk and olive stone mix" and make sure each inlet valve was shut and blast the port for about a minuet, the sandblaster also had a vacum hose built in that would carry all the waste back. I always had 100% success with this method and it was so easy just removing an inlet manifold, sometimes I would do the exhaust as well and even inlet manifold and EGR ports. I think snap-on & Forte used to make these kits.
A 2nd method of which i had excellent results was to fit a water bag in the engine bay with a pipe to the inlet manifold with a fine misting jet and clamp on the pipe to control the water flow and allow water mist to be sucked into the engine. belive it or not over a few hundered miles this will wash an inlet manifold and valves clean ! its remarkable to see but works brilliantly.
If you ever think of a cylinder where a head gasket has gone they are always carbon free where the water has washed the carbon away.
Ford escorts with sticking valves under acceleration responded brilliantly to water being sprayed in a fine mist. I have on occassions when I had some that were so bad they couldnt be driven was to leave them ticking over on the forcourt with a misty spray from a garden hose running in the air intake with gentle revs every now and again to watch out for water build up to prevent flooding the manifold or engine. I used to leave them running for about 4-5 hrs. never ever had to physically decoke one using this method.

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