Fuel consumption

[Hoppy]

Originally Posted by grolschie

Hi Hoppy.

Next service, I will get them to check plugs, o2 sensor and timing.

A good move if you can afford the cost, they don't do that for free.

Originally Posted by grolschie

I never use 91 octane, except for this NZ new '94 Galant SEI 2.0 SOHC I just bought today. It said 91 Octane inside the petrol flap, so filled it with 91. I wonder if 96 would be better though.

On a NZ model you should be sweet on 91, they are set up for that. You could try 96, but the benefit would be most noticeable if you advanced the ignition timing by 1-2deg (don't got outside specification)

Originally Posted by grolschie

I was told to buy AvGas from near the speedway in a petrol can and put 4L of it in per tank full in the Legnum. Apparently AvGas is the goods, and even such a small amount does a great difference. Only, the exhaust smell is a giveaway. ;-)

Av Gas - that will scrw any catalytic converter for sure - not to sure how good it would be for some other components. IIRC it has lead in it. I suggest you get it running good before you try anything like that.

[Hoppy]

Originally Posted by grolschie

'96 is good, but quality varies. I was using PowerPills with good success:
http://www.take-colostrum.co.nz/powerpills.html

I was told that putting foot down means little as the computer won't give it more gas than IT thinks is needed. I am not sure whether I believe that, and wonder if driving with foot hardly on the pedal results in more economy - as opposed to heavier foot with same performance.

Not too sure exactly how Mitsi's work, but fuel injected cars computers generally have 2 modes.

Open loop & closed loop. I can never remember which one is which but the differences are:

Open loop: The computer determines fuel input by means of a preset "map". This is used during warm up, idle (usually) and under heavy acceleration. This means that if you put your foot down it WILL put in the amount of fuel specified for the throtle position.

Closed loop: The computer determines fuel input from afformentioned map BUT will adjust it based on the feedback from sensors, such as the 02 sensor in the exhaust that checks richness/leaness. This mode operates whenever you are cruising to minimise emissions and optimise economy. If any of the sensors are bung (especially the O2 sensor) - then kiss your economy goodbye.

A computer check should advise of any faults in these systems. (You can sometimes do this yourself if you can find out how to start the test mode. In some cars (Nissan) the results are displayed via "engine" light on dashboard flashing back a code)

[grolschie]

Aircon is set at 17c, fan on 1/2. :-)

I didn't realise that fan speed inside car affects how much work the aircon unit does. I thought the aircon unit at the motor was either on or off.

[Hoppy]

High fan speed will mean that more air has to be cooled, therefore the compressor will have to run constantly to cool all that air. At lower fan speeds there is less air to cool so the compressors often cycle on and off, or in some cars reduce the amount of compression, therefore reducing the drain on the engine.

Once the car is cool try setting the temp to about 20 - 23 (or whatever is comfortable) and set the fan to 1 or 2, or if you have it try the auto fan speed. In my Nissan that will adjust the fan speed and the amount of cooling to keep the set temperature.

The fans (Radiator fan - needed to cool the aircon heat exchanger and the cabin blower fan) do add up to a fair bit of power on their own - this will mean your generator will be working harder to keep the battery charged. This too will be stealing power from your engine, but not as much as the compressor.

[grolschie]

Thanks Hoppy for the infos. Car has no catalytic convertor. Removed it last year. Chews about 380km per tank around town at last test on 96RON. It's not an NZ model, it's a Jap import. I was told that they really need 100 Octane by the mechanic, one of the reasons they discontinue the GDI.

[irishgalantvrg]

Hey there , this stuff does the trick , worked for me . give it a go .

http://www.idealcarparts.com/default.htm?page=12

[grolschie]

We finally got 98 Octane gas in my town a week or so ago!!!! Car runs a little peppier now.

[fo-kem]

Hi Guys:

My car is also experiencing the same problems that yours are having.

mine is a 1996 gdi 1.8L with manual tranny. i have taken the car to three top auto electricians and the concensus is a DEFECTIVE GDI PUMP!!!

I could not source a new or used one for the 1996 models so he decided to do a conversion on a GDI PUMP from a 1998 model.

The car ran sweeeeeeet for one day but the pump burnt up 'cause a lubricating oil line to the pump was not re-connected.

Now i am wores off that i originally was as i appears that the pump was damage beyond repair and blah blah blah....

Can anyone post a drawing of the internals of the pump and how it works...i want to take a stab at fixing it myself.

i have to fix the problem befor i sell the car 'cause i wouldn't want my enemy to go through what i did.

[grolschie]

Originally Posted by fo-kem

Hi Guys:

My car is also experiencing the same problems that yours are having.

mine is a 1996 gdi 1.8L with manual tranny. i have taken the car to three top auto electricians and the concensus is a DEFECTIVE GDI PUMP!!!

I could not source a new or used one for the 1996 models so he decided to do a conversion on a GDI PUMP from a 1998 model.

The car ran sweeeeeeet for one day but the pump burnt up 'cause a lubricating oil line to the pump was not re-connected.

Now i am wores off that i originally was as i appears that the pump was damage beyond repair and blah blah blah....

Can anyone post a drawing of the internals of the pump and how it works...i want to take a stab at fixing it myself.

i have to fix the problem befor i sell the car 'cause i wouldn't want my enemy to go through what i did.

Ouch. I had both fuel pumps replaced in my car. The main one, the high pressure one cost NZ$2500 ($US$1750) fitted!!!! Just as well I bought a 3 year warranty.

[stustunz]

its the injectors that cause the surge i beleive plus the throttle boody needs to be cleaned every 30000km or so as they do not clean themselves like a normal car would (YOU WILL NEVER GET RID OF THE SURGE THEY ARE A BAD DESIGNED MOTOR END OF STORY)

[grolschie]

How does one clean the throttle body?

[stustunz]

either spray carb clean into intake around the butterfly somewhere (through a Vacuum hose is the easiest )keep revs up while doing it or car will stall and if to much is sprayed in at once could do damage(small chance but just do small squirts at a time
or the better method but if you do nt know what you are doing dont do this one remove conmplete intake manifold and soak in some sort of cleaner and spray carb clean down intake ports to clean the backs of the valves leave to soak over night

both these methods will get rid of ticking when the engine idles and increase power and make car run smoother for about a month or three depending on which way you do it

Cheers Stu

[Cab 4]

oh, bugger, i think i got this thread because i wanted to know why the crummy Holden that replaced my BELOVED Diamante SuperSaloon (as a taxi in the 'Naki) makes Steenky Sulphur Smells when i try to make it go as fast as the Mitsi did (which it doesn't, despite being 7 years newer and 800cc bigger). Siiigh...

About the only thing i can think of is that it's on LPG, does anyone know if LPG is infested with Sulphur?

[StevOdevO]

I have a crap Mitsubishi Legnum 1.8 add me to your list of disgruntled Mitsi owners, these cars are absolute rubbish, my fault for buying it I spose...here are the symptoms, A/ Very poor economy, haven't measured it, but have owned a V8 (350 chev) and it would be on par with that, except it has no where near the grunt. B/ Always feels like I'm towing a boat, a bloody big heavy boat. C/ It broke down today... and it has noisy lifters...

[sfk]

I'm having problems with my 1999 24 Viento GDI Legnum. Lately it has started to show idle problems when first started. Regardless of whether it is warm or cold, the engine hunts up and down revs and sometimes stalls. Problem goes away once the car is moving about.

The other problem is that is doesn't go into GDI mode any more. It used to. Adn you would notice the revs drop and the dash GDI light come on. Doesn't do it any more.

I have driven it 30,000k since buying it 2 years ago. It now has around 130,000k on the clock. It has been run on 91 octane fuel which I just found out is not a good idea

I am in New Zealand and apparently our fuel quality here is crappy. Too much sulphur and not enough octane. I assume the sulphur in the Exhaust Gas Recirculation system causes sooty carbon buildup in the intake manifold? Presumably this soot also fouls the engine sensors?

How does the ECU determine the right conditions for switching to GDI mode? What sensors could be faulty?

I took the intake pipe off the manifold and disconnected the airflow meter and sprayed a heap of Carb Cleaner into the manifold while the engine was running. I drove it afterwards and it seemed to start and idle better but I can't be sure.

While the intake pipe was off, I noticed that after the engine was switched off the Electronic Throttle was making a high pitched noise like the sound of a modem connecting to the internet. I investigated more and could see the throttle butterfly valve opening and closing before stopping a few seconds later. Why would the throttle be doing this if the engine is off?

The car drives fine in all other conditions, even though the fuel consumption seems pretty high compared to the weak output of the engine. Switching to higher octane fuel made a positive difference in power though.

What could the long term effects of running on low octane fuel be? Has this caused the engines GDI failure or is it the sulphur in the fuel?