black soot on my bumper?

[suss_slide]

hey people ive noticed that my car gets quite a build up of black soot on the entire back end. Now ive read this could be due to running rich. So im just wondering can i drop it off at a mechanic and he can tune it to fix it running rich? or what the hell do i do? cos i dont like this crap fuel economy business. The car in question is a mx83 cressida with a 1JZ. Standard apart from dumps. im struggling to get more then 350km out of a 70L tank. Also the car runs fine and isnt jerky at all.

[TRDcelica90]

could be a shit O2 sensor? assuming that you service it reg and have done all the ignition components?

[suss_slide]

Yeah I've changed the plugs they were very black. I've also found some milky oil under the oil cap, buts it's not coolant I'm guessing it's fuel and not water as I don't have any cooling issues.

[HAVABEER]

normally its just running rich from when the turbo's kick in and the computer decides to dump more fuel in there

there's probably a more accurate way of describing whats happeneing but i'm not really sure what it is.

you'll find a alot of turbo cars do this, my 1jz soarer does and i have the same problem of black soot all over my bumper

[Kedderz]

Up the boost to lean it out

[The Last Streetfighter]

Take a dyno run and check what the AFR's are doing. These cars usually run a bit rich in various parts of the range. If it is "normal" look at running an emanage, AFC, Jaycar DFA or something to tune it a bit.

[Z2TT]

Bad fuel economy? Check/Change Oxygen Sensor, Coolant Temp Sensor (For ECU), and Fuel Filter, Get Injectors cleaned.

[Dr. Twinky]

If there is soot on the rear bumper and your plugs are black then it is most definately running rich.
Change your o2 sensor and put fresh fuel in there - maybe also clean your spark plugs / change them and then see how you go.

I would rather it running rich than lean anyway - but crap fuel consumption is just crap.

Last resort get a new ECU and a fresh tune. Should see better power and better fuel economy.

[allencr]

I've also found some milky oil under the oil cap, buts it's not coolant I'm guessing it's fuel and not water...

Bad guess, it's baseless!
It, AND the soot, says that it isn't getting up to operating temp because it doesn't have a thermostat or is only driven on short trips by an old lady.

[Dr. Twinky]

Bad guess!
It, AND the soot, says that it isn't getting up to operating temp because it doesn't have a thermostat or is only driven on short trips by an old lady.

Cappucino is not good, whether it be fuel OR water.

[lt1972]

fuel mixes with oil and wont go milky, but fuel will thin your oil out. as thins is not your problem thats not a worry. however milky is water and oil mixed together just like mayo. more than likely if it is only like this on the underside of the oil cap (we talking oil cap on rocker cover) it is caused by condensation - cold rocker cover on start up meets warm crankcase gases = condensation = mayo.
black soot + sooty spark plugs = running rich.
370km per tank on 1J not necessary poor economy, all depends how hard your driving. ie when i was driving my old carby 2tg celica on average i got 400km, but when i went on cruise with car club i may only get 180km. anyway my definition of poor fuel eco was my old 1 tonner 180km on 65l best - must say an old carby worked 5litre will do that though.

[{Mr Crabs}]

Condensatoin under the cap is very normal for a car not run often,Even more so if it is just for a few mins.

The black soot i call "The Black Death"mostly wasted fuel. Mostly due to problems mentioned.Under load most Toyota Engines run very rich.

Cheers

[suss_slide]

well ive just had a chat with the mechanic ill be gettin it tuned next week sometime. ill keep ya guys posted.

[HAVABEER]

how does the mechanic plan on tuning the stock ecu which controls the timing etc?
if theres a way to do it post it up here.

[Raven]

What type of fuel are you using ?

A lot of the unleaded fuels being sold through various fuel companies still are a long way behind the Japanese and European grades !

Back in the early 90's we were using 80 something RON now you can get 98RON at most Servo's ( Oz market Premium Unleaded at most places ) , the rest of the world have had 95RON as there base unleaded for 15 - 20 years , a 1JZ is not tuned from factory to run on poor grade fuels . Use only "Premium" .

Yes Toyota's are tuned a touch rich for when the turbo's come on , but using 70ltrs for 350k's aint so bad that's 20ltrs per 100k's !

If you are using standard unleaded about 30% - 40% of the soot on your bumper would be additive's mixed within the fuel to allow it to be run in all the prehistoric falcons and commodores still plaguing our roads without destroying there valves .