lots of carbon emmited!!

[grave77]

I had this problem recently, my car is running lower mileage than before ... torque is great engine runs smooth ... no hesitation at all ... but when I changed the spark plugs it was plated with carbon, also the exhaust is totally plated too. It seems like injecting more gas in the engine but I can’t seem to know why?!

[winfred]

check the common parts first, tune up, look for air leaks, fuel filter, that stuff needs to be looked at/changed before you do anything else, that will most likely solve the problem and if not you will not be be fighting possible worn out mantainance parts looking for the real problem

[grave77]

Well... I had this problem long time ago, but the engine torque was also low, I checked air leaks, so I changed are tubes and regulator valve I also changed the fuel filter and air filter, oil filter and spark plugs, I have also changed the distributor cap and high voltage coil too finally I changed the AFM too since the resistive line was wiped off. I have the injectors in my suspicion list. Any idea???

[stu1]

Enigne temperature sensor possibly? DME thinks car is cold so richens up the mixture.

Stu.

[Derek A.]

How far are you driving? Winter time will cause a decrease in fuel economy and these cars do not like to be started and shut down without being warmed up and driven.

[shogun]

Do you have the correct spark plugs inside.
Have a look here under spark plug conditions, how they look under different conditions and what you can "read" from it
http://www.vinesauto.com/techinfo.htm

[grave77]

This might be the one, but I can tell u here that I disconnected the O2 sensor 2 years ago, my ran very smooth without any carbon leftovers, now it does, can u tell me exactly where is the temperature sensor? And is there a way to bypass it for test sake?
My car really chokes when I full throttle until it’s warm. Sure u can see the black smoke in the mirror. And u smell the gas too.
I use BMW Bosch original spark plugs and they r new too, no signs but the powdery carbon buildups.

[JonE]

Running correct octane of gas for your application?

[grave77]

yeh sure ... I think it's octane 95 unleaded. what makes me wonder more that the torque is great !! it burns out with 265/35/18 wheels but I'm dumping like 35% of my fuel in carbon wastes... which I think is too much, to imagin the thing .. if u stand beside the exhaust for 2 min u will smell burnt gas on ur T-Shirt! as if u washed it with gas.

[grave77]

I read ur comment, sorry I didn’t reply so soon. in Dubai we have 2 seasons ( summer and super summer ) so don't worry about the cold weather the minimum was 15 C I don’t know how much in F ?? maybe something like 60 or 70, summer time we reach to 100 - 110 F that was from my cars temperature sensor. also the problem started in the end of the summer time when the weather was still hot. I think all of u wonder why don't I go and connect it to a diagnostic tool. the answer is that I can't find anyone in my neighborhood with it. all of them use their common sense which is mostly in accurate. that’s why I need some tips to start with then I can pin point the problem.
one guy told me that if u drive over 150,000 K then u need to change ur middle muffler the one after the catalytic converter. and by the way my catalytic converter is chipped off and replaced with Nissan Safari semi muffler pipes. ( it added few HP to the ride ). and that time it was running smooth without any wastes.