Ive got a GDI galant thats caused me loads of problems since the moment i brought it. Its an early 97 4G93 with the green sticker high pressure pump. Its currently running rich and im struggling to find the cause.

Ill list the things i have done so far to correct all of the issues ive had.

-New fuel filters all round + air filter
-Replaced high pressure fuel pump as original one had gone low pressure
-Completely stripped, cleaned and serviced the throttle body and idle valve + checked TPS and correctly set the idle using a scan tool.
-Acid dipped intake manifold to clean the carbon buildup off
-Cleaned and tested injectors on an asnu GDI test bench + new seals all round.
-Replaced failed o2 sensor with a bosch universal 4 wire and checked its operation with a scan tool
-Tested all coils
-Replaced spark plugs with correct ones - NGK BKR5EKUD
-Checked temp sensors for correct operation with scan tool + thermometer
-Blocked off EGR valve (was running rich before i did this.. so not likely to be the cause)[img]
-Checked air flow meter and compared with a known good one using a scan tool

After doing all the above its running 1000 times better than it ever did and the economy isnt too bad either (500km odd to a tank around town and an easy 650km on the open road) but the plugs are still covered in soot, indicating its a rich mixture. The electrodes and tip are clean but the body of the plug is black.



The only thing that im not sure about is the fuel pressure. If it were too high i imagine that may not be helping but as its the earlier high pressure pump its got no pressure sensor on it, which makes it that much more fun to check. We have tryed adjusting the fuel pressure but it doesnt really make much difference. It runs fine to a point then runs like rubbish in either direction so ive put back to where it originally was.

Any thoughts or suggestions?

Are you using super or premium? had the same prob car worked fine but the plugs said otherwise, i've just gotten to live with it, but i can be wrong but i believe that it's the gas, these engines were designed for 100 ron gas, our premium is 95 ron, i believe there may be some form of pre-detonation from the lower octane gas causing the build up. I can be wrong as hell though

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I think the original plug for the gdi is the ngk bkr6e-kuc

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you should check the lambda probe as this is a common problem in the gdi's and can cause the ecu to adjust fuel input causing the engine to run rich

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You should try a higher octane fuel and see if that will resolve the issue but rollingstock, also has some good ideas

^^^^^^^more details on this please ? sounds interesting

Try the plug i quoted, it's a 6 in the heat range, usually for turbo applications but the gdi engine has a compression of about 12:1 it requires the higher heat range.

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Yes i believe these were designed for 100+ octane. Here in new zealand we can get 95 and 98. It still runs just as black with 98 and as it runs no better or worse nor is the economy any better i use 95 as its a bit cheaper.

Trying to find out what the correct spark plugs were was also a bit of a mess. It originally had NGK BKR6EKUD plugs in it when i got it but they fouled up all the time. Depending on whos parts catalog you look at will give different results. Ive got a copy of ASA (the mitsi parts catalog) which says to use BKR5EKUD. Given they are a hotter plug they self clean properly too. I suspect the newer engine with the blue sticker fuel pump (mid 97 onwards) uses the BKR6EKUD plugs which is where the confusion comes from as the manufacturing date is important given the number of engine changes made.

The lambda sensor (o2 sensor) has been changed. The original one had a heater fault and didnt function although it didnt throw a check engine light or an error code which was strange. Trying to find the correct one to replace it with was a problem too. An OEM one was going to cost $700+ so a bosch universal one was fitted as its was only $80 odd. We couldnt find a cross reference to the OEM sensor anywhere so assumed it would work out ok. Under the right conditions it does function properly so i dont think the problem lies there. I could be wrong though but as i dont have access to a gas analyzer i carnt check that its within range.

wasup, nz, that's a far way off from me, if you were closer i could have gotten someone to check the o2 sensor for u, as this is a major shortfall with these engines.
For some reason it seems that the gdi in nz get a bad rep due to nagging issues, don't know if it still applies but i know that one of the problem with the gdi in nz was the gas, even though the octane rating is sufficient the gas is high sulfur, a no-no when it comes to gdi's. Is this still so?
Also did you use the original fuel filter, the replacement filters are a lot cheaper but soon causes problems to develop.
If used engines are easily available there try swapping in the 4g63 (no T) sohc , minor mods and can work with lower quality gas and does not have the issues of the gdi.

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The heat range on NGK plugs works backwards.. so a higher number is a colder plug and a lower number is a hotter plug.

Does anybody know much about the green sticker pumps? Theres a small solenoid fitted to the side that im not sure about. All it can really do is vary either the pressure or flow. But as these pumps dont have a pressure sensor the computer would have to just "guess" what it was doing if this is its function. I suspect this may be part of the problem.. but i dont know enough about what it does or when it does it to actually check.

Im not sure about the sulfur content in the petrol here but the GDI has gotten a bad name given all the issues they tend to have. Having said that.. there are heaps of them on the road here. Ive seen a few with 300k + on the clock and still going fine so who knows. The major issue here is that no one knows enough about them to actually diagnose the problems. Mitsi themselves are useless and dont know what they are doing.. and as the GDI was an import they dont really care about it either.

Had to use an original mitsi fuel filter as there were no after market equivalent filters available here. Ive changed the filters in the high pressure pump too.

I was aware of of the 4G63 swap being fairly straight forward but since the GDI still runs alright (apart from being rich) i didnt see much point in going down that line. Once it completely dies that may be a good option.

realised what i wrote after i posted it.

Only way to test the pump is to attach it to a high pressure gauge, the solenoid is to adjust the pressure i believe. If you're not getting any symptoms of pump failure i'll leave the pump alone, these thing can be finicky, plus if you're running rich there's fuel delivery. i have a 97 gdi with the green sticker pump and the ngk 6 plug is recommended. If the plugs are fouling try disconnecting the egr valve for a while and see what happens.

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Have done.. other than emissions purposes and filling the intake with crud it doesnt serve much of a purpose. Ive got a plate across mine.. which made little to no difference. The intake manifold stays nice and clean now though

I'll talk to my tech later and see what i can find out for you, what u have is a unique problem 'a lean burn engine running rich'

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Haha.. thats prety much true! As it runs fine and its not causing any problems im happy with it as is, but there must be something thats causing it to run rich, which is just burning more petrol than required. Ive heard of some GDIs getting as much as 750k from a tank of petrol, which would be nice with todays petrol prices!

Thats what the BKR6EKUD's came out looking like.. Nice and tasty black. The hotter plug definitely run cleaner!

I can also supply and log any ECU sensor readings via OBDII live data if you think theres anything useful that may be of help.

Did you remove the thermostat?

The thermostat is in there and it comes up to temp properly so its functioning correctly. Dont quite see how that may influence the richness of the mixture though.

Mitsubishi, all models 1993 - 2004 onwards

Emission Failures -common causes of rich running faults are the O2 sensor or the ECU (engine control unit) both of these parts are relatively simple to check, to check the O2 sensor strip back the insulation on the signal wire from the O2 sensor, this wire is usually black. Then hold the bare wire between your finger and thumb then touch your other hand on to the battery positive the internal resistance of your body will give 1volt at your finger tips which is what the sensor would give out when the engine runs rich, if the emissions come down then you have a faulty lamna sensor or wiring but if the emissions remain the same then the ECU is a possible fault.

Ok I gone

Spoke to tech, he say bring the car, i told him he's an arse
It could be the o2 sensor, the bosch universal sensor maybe the prob, by chance do you have an aftermarket ram type filter installed.

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^^^^^^^^^ Water temp sensor make sure that one is working. I met a guy with a faulty unit that also made the ECU run rich

I had a pod filter on it for a little while but even with the factory air box/filter it still ran rich. Im not sure if the bosch universal sensor is the issue or not. Ive not managed to find enough info about the factory sensor to suggest its any different from a standard o2 sensor, so who knows.

Have checked the temp sensor. The ECU reads it correctly too.

I have got another ECU that i might try swapping over and see if that makes any difference.

Either ecu or o2 sensor by all indications.

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Life is short, Break the rules, Forgive quickly, Kiss slowly, Love Truly, Laugh uncontrollably, never regret anything that made you Smile.

I got this Galant GDI 97 and have same problem. Can anyone tell me what OBD scanner can read ECU? I know Carman can but its quite expensive. Are any other scanners?

have evoscan if u want to try it .

tnx I am in Australia (Brisbane). Ship my Galant over here and can't find anything on this car here Heve you try evoscan on 97 Galant VRG?

yes it works......