Assess my engine condition from these plugs

[wandee 0]

1994 VR6 with 107K miles on it. The engine is not actually giving me any performance problems...fires up beautifully hot or cold, pulls sweetly throughout the revs and has no misfires or flat spots etc. However it's never been great on mpg, and only starts to get approximately 25mpg once fully warmed up (driving in normal traffic conditions), but up till then my my MFA average reading is around the 20.1 mark.

 

Slightly more concerning is the fact that it has recently started to get rather thirsty for oil. I noticed a couple of months ago that the oil level had dropped just below the minimum level on the dipstick so I topped it up with a an extra litre. That was around 800 miles ago but a couple of weeks ago whilst driving to work the dreaded oil beeper started constantly sounding off and, naturally, I nearly wet myself and headed to the nearest Halfords for another litre, which seemed to cure it.

 

Anyway driving home last night the beeper momentarily went off again for a few seconds and then, thankfully, stopped. I got home safely and checked the oil level when cold first thing this morning. The oil level was in the middle of the min/max crosshatched area of the dipstick so low oil level cannot have been the thing that set the beeper away again.

 

The car has always puffed a bit of black smoke but I cant say I've ever noticed any blue. Anyway I whipped out the plugs and the photos below show them in all their glory.

 

Any initial thoughts?

 

http://i614.photobucket.com/albums/tt225/TMJ1972/plugs2.jpg

 

http://i614.photobucket.com/albums/tt225/TMJ1972/plugs3.jpg

 

http://i614.photobucket.com/albums/tt225/TMJ1972/plugs4.jpg

 

http://i614.photobucket.com/albums/tt225/TMJ1972/plugs5.jpg

 

http://i614.photobucket.com/albums/tt225/TMJ1972/plugs6.jpg

 

http://i614.photobucket.com/albums/tt225/TMJ1972/plugs1.jpg

[pete_griff 0]

apologies i'm no massive plugs guru (hopefully someone who's a bit more clued up will answer you before long).

 

those don't look all that bad to me though...

it's relatively normal for a VR to become a bit "oil thirsty" as the miles pile on with valve-stem seals etc going brittle with age and the bores glazing up.

those plugs don't look all that bad though - obviously there is some oil getting in - but it doesn't look to be a horrendous amount (again - IMO).

 

don't want to worry you, but it's a little concerning to hear that you're getting the oil buzzer when the reading is still halfway between the min/max marks :? - do you absolutely tank it round the bends??? if you're getting the buzzer, then the oil pressure loss might be due to something else; is the engine particularly noisy at all?

[wandee 0]

No I never really tank the car at all...having said that I think I should retract my statement about the oil level being ok as I checked it again this afternoon with the engine warmed up and the car standing still and the level had dropped below the minimum again so this confirms without a doubt that it is using up the oil much too quickly.

 

My own synopsis on the plugs is that they are pretty damned sooty which explains to me why the car's mpg is not great. The soot was not baked on however as a quick wipe with a cloth got them nice and clean again. The small amounts of oil on a couple of the plugs are a mystery to me though...I mean there is even oil on the threads of some of the plugs and I have no idea how that could happen as there are no actual oil leaks on the engine whatsoever.

[davidwort 0]

They all look far too black to me, over fuelling? should only have small amounts of light brown deposits over thousands of miles really, not all sooty like that, if it was an oil burning issue I would have thought one or two would be much worse than the others and oily rather than sooty. Needs fault check I reckon, make sure all the sensors are running in spec.

[Toad 0]

Yeah, I agree with Mr Wort. I would change your blue temp sender (sender for the ECU) as a first resort. Or at least check they are connected the right way round.

[dirtytorque 0]

Did you take those plugs out once the engine had warmed up properly?

[wandee 0]

Blue temperature sensor was changed approximately 1000 miles ago. Before that it was getting hideously bad mpg...17mpg in all conditions. :shock:

 

The plugs were taken out with the engine not far off normal working temperature.

[Toad 0]

get VAG COM on the case.

 

What's the water temp showing?

[wandee 0]

The water temp seems fine, never overheats and climbs to about the 80/90 degree mark. Not sure if it's a normal VR6 trait but mine seems to take an eternity to get to full temperature, a 20 minute drive to work and it's just starting to get somewhere near it.

 

I've been living with the overfueling issue for a while now. It's this new oil loss issue that is concerning me.

[Toad 0]

Hmmmmmm. Might be worth changing you thermostat. If that is sticking part open then the engine will be running cooler, plus if it takes that long to warm up, then it'll still be hanging around on the cold start map (

[wandee 0]

Yeah that's a good shout.

 

What about adjusting CO? I've done loads on Mk2 Golfs but have no idea where or how it's done on a VR6.

 

The previous owner of this car fitted no less than 3 lambda sensors so I'd be amazed if it had anything to do with that. :lol:

[Toad 0]

YOu can't adjust that on a VR, the fueling is controlled by the MAF, throttle position sensor and the Lambda, with the air temp sensor and coolant temp sensor making adjustments.

[wandee 0]

Hmm, VAGCOM it is then. Anyone got it in the Newcastle area? Apart from the stealers obviously....

[Supercharged 2]

Deffo sounds like thermostat - should be up to temp in 5 mins in this weather... under 80c and it will be stuck on the fuel enrichment map.