I took the plugs out of my MK3 today to have a look at the condition of them.
The ends are blackened with carbon stuff. And they should be browny sand colour. Its not oil because its just like carbon dust.
Looking in the haynes manual it says over-rich mixture.
Could this be anything to do with the water/petrol stuff shooting out my exhaust when you rev it. As where its coming out the exhaust and drying its leaving sooty carbon stuff dried on the end of the tail pipe.
How much are a new set of plugs, and how can i fix the problem.
Last edited by LongLiveTheNova; 17-09-2004 at 18:15.
Would this give crap performance and have anything to do with my car idling so high.
The fueling can't be changed though can it, its ECU controlled injection so theres no mixture screw or anything. It has to be done with an electronic tuner doesn't it.
I am gonna get some new plugs, and put them in after the car is fueling right.
ya over fueling can give bad performance, and when mine runs rich the revs go a bit higher, so that is inline with whats happening to yours.
I dont know about yours, but I would be pretty sure there is a mixture screw on most cars!
Unless your plugs are old, there is no point in changing them. When the car is running the right mix, the carbon stuff will go away and the browny colour will come back after about 15 mins of normal running.
I can't see there being a mixture screw on it, as its all controlled by sensors to the ecu.
But i think overfueling is cause by a mis behaving lambda sensor, i get no management light, but i read that it some times supplies incorrect levels, but it don't register as faulty and bring the ecu light on.
Yeah thats why i though it was a bit funny for the lambda, as it passed emissions(or at least they said it passed, cus i had the clutch done at the same time so i doubt they were gonna turn down money as i told them not to do the clutch if it failed MOT)
I will pick up some NGK plugs tomorrow, my ones now are looking a bit rusty anyway.
Is the lambda the only thing that can cause overfueling, or can inccorect timing cause it.
Today i started it and it was idling again at about 1600rpm, so i switched it off, and started it again straight away and it started and idled at about 900rpm, perfect smooth idle. I revved it and to my suprise the revs fell quick and smooth back to 900rpm.
I ain't cleaned anything cus i can't get the ICV off, so how can it do that. Is it idling high due to too much fuel, but how come it idled at 1600rpm. switched off, back on straight away and it settled at 900rpm and stayed there throughout the temperature range. It was acting like it should. How can the idle vary like that.