Got a 1998 Diamante, GDI direct injection 3.0 v6, done only 47000km

Grey smoke comes out the exhaust on cold start up, close in colour to cold morning water vapour but a bit darker and hangs in the air differently, so def not water vapour. It's just like a big puff and then nothing. Also same smoke comes out under heavy acceleration, about 4500rpm and above BUT not all the time, maybe 75% of the time, sometimes nothing comes out or very minimal.

under load, it can feel like it's misfiring or has a little stutter, acceleration not smooth. but normal driving off from standstill is fine (if not hard accelerating), but turn a 90degree corner at an intersection with it staying in 3rd accelerating from 1500rpm or so up to 60k gives a stutter up the rev range. doesnt stutter over about 3500rpm

Also idles at 500rpm in drive, doesnt make a difference if A/C is on or off. in neutral would idle around 600rpm. Mitsi have checked and reset base idle settings but made no difference.

aaaaand this morning when i started her up it was idling about 1500rpm (normal cold start) and it was misfiring (i think) quite a bit. was idling like 'duuuuuuuum-d-d-d duuuuuuuuuuuuuum-d-d-d-d-duuuuuuuuuuuuuuuum' if that makes sense. has only started doing this recently. a few weeks ago on the way home it ran on 5 cylinders for about 20 secs, put her in neutral and gave it a rev and that fixed it.

I've had full service, new air filter, fuel filter, fuel system/injectors cleaned. oil goes black very quick and does burn a little over time. is pretty gutless too, doesnt feel anything near the power it's meant to and uses fair amount of fuel, 14.3l/100k in town (bear in mind GDI meant to use 30% less than normal similar sized engines and a lot of owners get 9.5-10l/100k in town)

doooh, sorry to write so much but trying to give as much detail as possible. any suggestions on what could be the problem(s), what to try next? Mitsi have had on diagnostic machine and nothing came up.

time for a new car? haha

Mate I'd say your car is running quite rich if your oil is going black that quickly, and your fuel consumption is that high.

Was the oxygen sensor ever considered? If it's burned out/given up, it'll send the wrong signals to the ECU, causing the ECU to pump more fuel than is necessary in.

mmm yes i was thinking that could be it.

I'm going to check a spark plug or 2 this weekend to check the colouring/appearance etc, what would it look like if it's running rich?

the oxygen sensor didnt come up faulty on the computer machine, but i might get that looked at next week when i'm on leave from work :D

when i got the car a year ago it was doing low 12l/100k and steadily gone up since (altho have changed from 15's to 18's also)

also just thought of something. pretty certain it only started smoking after the first service, changed from unknown oil to Magnatec. maybe i should try something else.

If the motor is running rich, the plug will look like it's come out of an oil well, ie. black, oily, greasy, clogged with crap.

As far as I know, the EGO sensor won't throw a code/error, as it's considered to be a 'consumable'.

What weight oil are you running? What type of fuel are you using?

The GDI engines are way cool, but I understand that they're very finnicky, especially when it comes to fuel.

Sweet, thanks for the info :bowrofl:

i'm using 10/40, recommended is 10/30 so didnt think it would matter too much... i used this oil in my last car no probs, but that was quite a different car. might try something else next time. i'm using BP Ultimate, have been for bout 95% of the time i've had. $110 to fill is a b1tch tho! haha especially for only 450k

yep, cool when they work properly ;) if i knew then what i know now, i'd definitely have gotten the older Mivec model 0-100k in 6.6 seconds instead of 9 and bit currently ;( 177kw my ass

Check the distributor and leads also, and ensure the timing is correct too. Misfiring could even be a leaking head gasket, so you might want to do a compression test to ensure this is not the case. All of these things can cause the ECU to pull back to a partly fail-safe mode, where it will just run the engine rich for safety reasons, as running an engine rich won't destroy it in the way a lean mixture will.

thanks, will look into this too.

if the head gasket was leaking, wouldnt that make the oil frothy from water getting into the oil or is that only the case with a fully blown head gasket?

thanks, will look into this too.

if the head gasket was leaking, wouldnt that make the oil frothy from water getting into the oil or is that only the case with a fully blown head gasket?

Not always. It depends on how severe and where the leak is. Sometimes there can just be a leak between the water channels and the cylinder, or oil to the cylinder. In the case of the oil, it's under high pressure, so a leak between oil and water you would most likely see oil in the coolant than the other other way around.

You can get it checked by taking it to a tuning specialist. They have gas meters that can check whether there is a leak between then cylinder and coolant. Or as a basic quick check, you can just run the car (while cold) with the radiator cap off and watch for bubbles or oily residue running through the radiator.

OIC, thanks for the info.

Have taken off the engine cover to check out the plugs etc, wasn't what i was expecting! appears to have direct ignition or something... not sure what to do next so might wait for dad to come home before going further!

http://i16.tinypic.com/68ax6kn.jpg

http://i10.tinypic.com/6b2nga0.jpg

well this is what my plugs are looking like...

http://i10.tinypic.com/52nwoqw.jpg

but before i change them, have to find out what's causing this first otherwise will be throwing money down the drain

With plugs in that sort of condition there are a couple of things I would check first.

Check to be sure that the oxygen sensors are working correctly, as dead ones will cause the engine to run extremely rich. This will carbon foul the plugs very quickly due to incorrect mixture.

Secondly, check the air filter. A friend of mine had similar issues in her car, and after looking at it, I found the air filter was so clogged the mixture was being stuffed up that way.

The plugs do not look oily, so I doubt that there would be leaking rings or anything like that. Maybe do a quick compression test too, and if you find one of the cylinders is down a bit in any of the cylinders, put a small amount of engine oil in and try again. If the compression improves, there is an issue with rings.

Cheers. I replaced the filter when i bought the car 11 months ago, but might look into a drop in K&N panel filter.

on Tuesday i'm going to an auto electronics specialist and taking this photo in of the plug and will get them to check out the oxygen sensor and anything else. will suggest about the compression test etc

hopefully things will improve from there :shock:

Also another sensor that can make it run rich apart from the oxy-sensor is the temp sensor and most times that packs it in before the oxy sensor.

took to auto electrician today, confirmed it was a faulty o2 sensor connection.

all fixed and going good now :) just gotta change the plugs tonight/tomorrow and also going to change the oil cos i have this feeling (probably false) that cos i was running so rich for so long, that there is fuel in the oil so best to change it

The oil will probably be a bit black from blowby and fuel contamination, so a change will definetely do it good :)