carbon deposit?

[RiversideS13]

I have a 91 ka24de with 200k miles and i dont know why i have soooo many carbon deposit came out from my exhaust pipe. They are usually accompanied with water. i thought i am running rich and i replaced MAF, O2 sensor, coolant temperature sensor with harness, air filter, fuel filter, cap and rotor, spark plugs, seafoam it ...etc. still does the same. however my mpg improve from 21-22 to 24-25.

my car runs a little bit sluggish i think it might be because the RSR 3" exhaust.

but can anyone tell me why my car shoot out so many carbon particles?

[HyperTek]

put some crap spark plugs in an old o2 sensor and run seafoam

[brokeAs240sx]

I have a 91 ka24de with 200k miles




Reallly tho, do some general maintenance on your car. Just changing oil doesn't count.

[mrmephistopheles]

holy crap, talk about reading comprehension, guys.

i thought i am running rich and i replaced MAF, O2 sensor, coolant temperature sensor with harness, air filter, fuel filter, cap and rotor, spark plugs, seafoam it ...etc.

put some crap spark plugs in an old o2 sensor and run seafoam

He already did.

i thought i am running rich and i replaced MAF, O2 sensor, coolant temperature sensor with harness, air filter, fuel filter, cap and rotor, spark plugs, seafoam it ...etc.


Reallly tho, do some general maintenance on your car. Just changing oil doesn't count.

That's MORE than general maintenance.

[brokeAs240sx]

ok i apologize for my lack of reading skills.

Maybe if he did something like:

I did
- x
- y
- z

instead of

kjlkjlkjweijf k dkwj okjd x lkasj dflk y lksdjf lksjd z.

I'm a lazy reader.

[mrmephistopheles]

True enough.
More capitalization and punctuation would've gone a long way for making that post more readable.

[Jeff240sx]

Clogged cat? 4 bolts. Pull it off, and see how bad it is. You can try some carb cleaner or soak it in gasoline or something.. or replace it with a straight-through test pipe or a high flow cat.
-Jeff

[ledzeppelin240]

Don't take the cat off to check it, use one of those hand held temperature gauges and see what the inlet temp. of the cat it and the outlet temp should be at least 10% or greater, this shows that the cat is working.

What you should have done was see if those sensors were working instead of just replacing them. Diagnose the problem, then replace.

Your cat might be done for or oil coming in contact with heat as well as carbon build up due to fuel…

[S14DB]

PCV valve FTW1!!

[BlackSilEighty]

Is it still putting out good power when your driving it? It could be a cracked head or bad lifters if not.

It could just be burning oil. Take it to a good Nissan place and have them look at it. Mine was doing something similar (smoking at stop lights and what looked like steam coming out of the muffler).

They looked it over and told me my valve seals were a little dry and it was burning off oil. They told me I needed to start running 20w50 high mileage motor oil. Fixed it right up.

Hope this helps :D

[kandyflip445]

PCV valve FTW1!!

That would cause sludge.

[S14DB]

That would cause sludge.
Depends if it's stuck open or closed.

[kandyflip445]

If it was stuck open it would eventually get clogged by sludge/oil. If it was closed it would cause oil blow-by.

[marshun]

its just the cat. go ahead and change it out. i had that question in myhead too before, but after i eliminated the cat, it was fine

[RiversideS13]

Thanks for your responses,

my car still has some resonable power and lay out 24-25 mpg in mix of driving.

what is "PCV valve FTW1!!" ??

and why eliminated the cat would help? i mean someone told me that a proper working cat should catch those those little black practicle and burn it out instead shoot out from my exhaust.

[RiversideS13]

here are pictures:

notice the black trail...which was a build up from everyday warm up
http://members.dslextreme.com/users/josephlee/carbon1.JPG

close up
http://members.dslextreme.com/users/josephlee/carbon2.JPG

rear bumper
http://members.dslextreme.com/users/josephlee/carbon3.JPG

what is the best method to clean up those black praticles on my bumper?

[RiversideS13]

my new catco cat should be arrive by today....

i must smog my car by this week!!!

[aznpoopy]

is that gunk on the ground oily feeling?

i've read alot of old cars get the oil return gunked up with sludge so oil can't recycle quickly back into the oil pan.

the sludgy oil gets stuck up in the head and seeps into the cylinders from the valves, causing black sticky crap to spew out the exhaust.