Greetings to all, as a new member I have noted quite a lot of references to fuel octane ratings and associated problems with carbon build up in the engine.

We have had our 1998 2.4GDI Spacewagon for just over 3 years covering about 30,000 miles. Total mileage on car - 98,000.

Our first breakdown occurred yesterday when the engine management system warning light came on with significant loss of power, upon pulling into the side of the road the engine cut-out. However, after a short wait the engine started ok again and all now seems to be fine.

I am unable to gain much info on the ECU operation, but consider that the loss of power may be associated with the ECU reverting to an "emergency" mode, would this assumption be correct ?. In addition will the fault be recorded in the ECU to enable a subsequent diagnostic read-out at the Mitsu garage ?.

In addition to above, would be grateful if further info could be provided as to problems associated with carbon build up on GDi engine due to use of 95 Octane petrol and recommendations as to what octane/type of fuel should actually be used (Shell optimax etc). Slightly concerned about this due to mileage of vehicle and possible link to problem reported above.

Hi,

I have a 1999 2.4GDI SpaceWagon and have just had the same problem, it has covered 60k miles. Providing you dont disconnect the battery Mitsubishi will be able to tell you the fault code.

On mine, the engine management light came on, although it still drove pretty much ok. Switched off for a bit and eveything back to normal. Took the car to Mitsubishi and the error was due to the mixture being incorrect, ie. fuelling and exhaust emmisions were to high.

After some time investigating in the garage it turned out that the car had a large carbon build up in both the exhaust induction and head. Mitsubishi confirmed this is a common issue and it will require a stripdown and full decoke. Cost of over a grand. Days and Halfs work.

Have now spoken to numerous people in the trade and it is very common in these direct injection engines. Volvo also have the same problem with the 1.8 as it is the Mitsi engine.

Once decoked you are better off running on quality Super Unleaded or Optimax so the sulphar content is lower and it doesnt re-occur so quickly. Personally I wont buy another Mitsubishi after this, as I love the car but have been very dissapointed with this as it will never go away.

I would also get somebody to checkout your Throttle Body as it is very common for them to get coked up as well. A remanufactured one is about £500.

Cheers

Many thanks for advice, car is going into garage for service next week. have asked them to check the error codes and also for signs of coking up. Not sure I want to hear the result !.

Again many thanks, will advise on result for info to any other members, surely misubishi should provide advice on this potential problem in the owners handbook !!!.
Am I being naive. The car has been operated in accordance with the owners handbook, as it does state that 95 octane fuel can be used. But if so many people are having this problem then clearly this statement may be incorrect.

May be worth taking legal advice, any thoughts !.

Regards.

Before my car finally went to Mitsubishi I took it to 2 other garages, both confirmed the same problem. Just is an inherant problem of the GDI engines and also the fact that they have an EGR valve doesnt help either.

Using super unleaded will not remove the problem; only delay it for a bit longer due to it being higher quality fuel.

I know somebody who works for Volvo and they have had cars in at 1yr old with the 1.8 engine and they have needed a decoke. If under warranty it is free of course. Apparantly some dealers use walnut shells to blast the engine clean; this removes the need for the head off etc.

Volkswagen are also suffering similar issues with there new FSI engines as well. My motto now is to never buy a direct injection petrol engine again, not until we get some decent petrol in the uk anyway. Japan and Germany etc have over 100 ron fuel at loads of petrol stations.

With reference to the 95 ron fuel, it is a requirement for all new cars to be able to run on it. Unfortunately there is no requirement for analysis of how well your engine reacts to it. For example I have a Subaru Impreza 1yr old and it states you can only put 98ron pertrol in which means optimax only.

However Subaru UK say it will run fine on 95ron although it will retard the engine and reduce the performance. By checking this with a knock sensor it means that basically the engine is pinking all the time.

Many thanks for advice very much appreciated.

With regard to my particular problem, I have been able to spend a bit more time evaulating the fault and have got a better understanding of what is going on.

Essentially what is happening is that the EMS warning light starts flashing, engine power is lost and the engine quite quickly stops when the accellerator pedal is quickly or fully depressed.
After coasting to a halt and switching of the ignition for a short period (30 secs to a minute) the system resets itself and you are able to restart the engine and drive away quite happily with EMS light extinguished. In some ways this is not to bad a thing as it encourages you to drive economically !.
To me this is pointing toward a possible EMS sensor or servo fault, as opposed to an emissions problem.

Either way I now have more confidence that it should be a fairly straightforward procedure for the garage to diagnose the fault. At the same time I will get them to check for signs of the engine coking up to give me an indication as to any future expense particulary as the the MOT is due in march.

Looks like we might have to start saving up for the Grandis as long as that is not a direct injection engine also.

Hi,

If you could let me know how you get on it would be much appreciated. As there arent a massive ammount of people with these cars, any additional info helps us all.

Sounds like your problem will hopefully be a sensor somewhere that has perhaps failed. The common one is the lambda sensor which is located on the exhaust system pretty much directly under the drivers seat. You have to unbolt the front drivers seat and get under the carpet to disconnect and check it which although doesnt take to long is a bit of a pain.

The other main sensor is the airflow sensor which can easily be reset by unplugging it and plugging back in again. It is located inline next to the air box.

Hope it is something simple,

Regards,

andy

Not a problem, will post result next week.

ian.

Received news from garage, problem is related to throttle body, new one required, due to throttle sticking through build up.
Garage are unable to clean the existing as it is a sealed unit. Suffice to say- not cheap.
get car back on Thursday.

Ian.

Thanks for letting me know, I am keeping an eye on mine as I did get it cleaned out as much as poss by an independant garage before the decoke; however they couldnt do much with it so keeping my eye on scrappers and ebay for replacement ready.

Just out of interest I was recommended this place for throttle body's

http://www.bba-reman.com/catalogue/Detaile...ailedProduct=48
Replacement throttle body is £425.

Fortunately I know a couple of mechanics who could fit it easily so I dont have to pay Mitsi labour rates.

Car now back from Garage, repair seems to have done the trick, certainly the engine seems more responsive. Unfortunately I paid full Mitsubishi prices, but thanks for link to alternate supplier.
many thanks for all the advice.

Ian.