car spitting out black stuff

[silvr6]

Hey, my car (vs series 1 v6) seems to be spitting out some black soot type stuff out the exhaust, is this a sign its running rich? as it does have a fuel consumption issue heres a pic, it really shoots out when you give it some revs



Any ideas whats causing it?

[dmitch]

running rich.. but that pretty bad.. check ur error codes..

[silvr6]

its got a dump pipe on the end so it might be putting out more then usual, its not all from the one starting the patch closes is probaly two or three starts and revs worth

and error codes are just bringing up 12 so nothing wrong there

[kopper69]

I normally get a couple of drops of water out of the exhaust on startup. I assume its just the cats turning CO2 into H2O, and a bit of standard black exhaust to make a slightly black water. Never that much though.

[J_D]

If its putting out excessive amounts of water/steam you might have a blown head gasket. I dont think you would get the soot falling in that pattern unless there was quite a bit of water involved.

[silvr6]

dont think its a blown head gasket however ill check it out, any other possible causes?

[Fletch_QLD]

It's basically unburnt fuel - what's your consumption like ? Plenty of potential causes for it to run rich. For starters there is replace air filter, iac valve could use a clean and possibly clean throttle body, check o2 and flow sensors - these can be performing poorly yet fail to throw out a code, I can't think of anything else that you don't need a mechanic for ?

[silvr6]

yeah fuel consumption is pretty bad about 320km a tank

by flow sensors you mean the maf sensor near the airbox?

might take throttle body off and clean iac valve later and give the o2 sensors a check hopefully can find my problem, i can do most things mechanically its just learning exactly what these sensors do or better yet what happens when they aint working

[Fletch_QLD]

Yeh - the maf sensor near the airbox, and the o2 sensors on the exhaust. The only wy to check them is to swap them out with known good ones though - so that ain't much help.

Also the temp sensor can cause the 'choke' to stay on - that is, the 'puter enriches the fuel mix when the car is cold - when the car ain't cold but the 'puter thinks it is, you get too much fuel.

[silvr6]

ok went for drive before noticed temp guage was on cold the bottom line and drove for about 10kms and it went up to probaly just under half way too the half way mark so if its correct then i think its running cold which would indicate computer it running the fuel mix rich

what sensor causes this, air temp sensor? or could it be thermostat? they also have a coolant sensor if im correct?

[nizmovk]

if you park yor car out side then it also could be condensation/rain running in over nite. As kids we had to wash teachers cars for punishment and used to run the hose up the exhaust...makes an excellent water canon!! muffler wouldn't like it much though in hind sight...

[Fletch_QLD]

ok went for drive before noticed temp guage was on cold the bottom line and drove for about 10kms and it went up to probaly just under half way too the half way mark so if its correct then i think its running cold which would indicate computer it running the fuel mix rich

what sensor causes this, air temp sensor? or could it be thermostat? they also have a coolant sensor if im correct?

There are two coolants sensors - one for the gauge, and one for the computer. The one for the computer is a simple on/off setup whereas the gauge one feeds back variable response - I'm not convinced that yours is running cold - 10k ain't enough to diagnose that, and it does sound like your thermostat is opening up, so I wouldn't sweat it.

Check your air filter, clean up the throttle body and iac valve - spark plugs if they are due (even whip them out and clean them up) - possibly even fuel filter if it's time. Start with the basics, see if things improve b4 you get on to the technical stuff. Once you've done the basics, it may be worth taking it to a holden dealer and ask them to diagnose poor fuel economy (and describe the black soot) Chances are they'll tell you it need an injector clean and de-coking. 9/10 that these are cop outs and attempts to get a hold of your hard earned imho. They can test your maf sensor though, which is far too expensive to be replacing 'just in case',

If one of your spark plugs is more fouled than the rest - maybe the injectors need cleaning - but who knows? I struggle along myself with not enough knowledge on these things, but too much self respect to be ripped off by the small number of mechanics out there that take you for a ride if you let them.

[silvr6]

thanks alot fletch, yeah still sticking with the basics like cleaning things up, going to check out spark plugs, air filter is fine may give it a change of oil and things which it maybe due for (have not had car a long time)

Im currently running injector cleaner in it now and going to run another lot next fill up to help out abit, my last option will be to take it to holden and see if they can pin point my problem

I was convinced it was running cold, cause the gauge barely moved from the bottom it was abit of spirited driving, i used to have a VN and within the same stretch of road it was running alot warmer and so does my vx SS, but it maybe a little fault the temp gauge that is

[Stewart1000]

have you been parking the car in a different place than you used to?

or driving it harder, with more revs?
if you granny it for a long time the exhaust gasses have been travelling slowly through the exhaust system and that allows carbon to settle and collect in the mufflers and pipes, and then if you park the car outside, it gets condensation inside the system and out comes that wet sut when you give her a few revs.

but yeah if thats the case it shouldn't do it all the time, it could be running very rich, i dont know how many oxy sensors the VN's have 1 or 2, maybe swap them with a mates car and see if the performance of the3 car changes, if it gets bettwe yours are stuffed, if it gets worse, your mates are stuffed, if its the same look further, like MAP sensor possibly.
Good luck

[silvr6]

car is parked in doors normally try to give it a run atleast once a day, once she warms up it dont spit it out anymore so its possible its a build up but i got a feeling its still running rich because of the fuel consumption issue, almost finished cleaning up some sensors and throttle body so hopefully will sort this issue out