had this problem for a while now, but have been to focussed on other things to worry about this.

i have these black deposits appearing around my exhaust tip and my bumper. infact my bumper gets quite dirty. had this problem when the car was carby also so im guessing its probably not something to do with the efi components.

any ideas on what could be causing this?

I thought it was normal to have a blackened exhaust being an unleaded vehicle

whats the oil consumption and fuel figures like ?

is it puffing smoke at startup ?

doesnt use hardly any oil. uses about 12l/100k which is good imho
puffs smoke on cold start

i thought it was normal too until my uncle said to me that it shouldnt be doing that.

mine did it and there was never a whif of smoke on startup, but the bumper constantly got deposits on it. I'd reckon its a fairly normal thing for a lot of cars. Depends how much buildup you get its hard to say really.

Exhaust is normal to be black.. especially on older cars.. on the bumper though, could be better than that. Maybe try fuel system clean and new fuel filter etc. Then you could try buying a dump tip so it sprays the ground and not your bumper lol

an idea

have an exhaust shop
add a pipe so it extends past the bumper

or a chrome tip on the end

Black is un burnt fuel generally....driving hard etc

Black is un burnt fuel generally....driving hard etc

or could be plugs not burning all the fuel, or there is more fuel in the cyls then there should be... well from what i've learnt on older cars pre-85.

ok so i agree that extending the exhaust will help solve the problem of the deposits on the bumper. but im not likely to do this anytime soon.

i do drive it hard now and again but i dont believe this is the sole cause of the deposits because it seems to be happening consistently.



or could be plugs not burning all the fuel, or there is more fuel in the cyls then there should be... well from what i've learnt on older cars pre-85.

How can i find this out? and then possibly fix it? is it worth the bother?

from what i remember of how my old man and i did on a straight 6/v8. (so maybe little rusty on this) pull ur plugs, check for any black gunk at the point, and also check the gap of the spark plug with a gap gauge, (dun remember what its called) that would tell you if the problems in the cyl itself,

check the dist cap and spark plug cables for any deterioration, (if so then not enough spark) but the later, (to much fuel in the cyl) im not quite sure, maybe check the valves see if they are seated properly, or remove the rocker cover and check that the valves/springs are at the right torque, (dunno what they are ment to be so cant tell ya on that)

Could be bad O2 sensor as well, running rich.

Could be bad O2 sensor as well, running rich.

o2 sensor only comes into play when crusing, under hard acceleration the sensor isn't able to feed any real usable info back to the ecu as it takes a while for it to get an accurate reading. air/fuel is purely off the fuel map.

black smoke = unburnt fuel. i'd be tempted to check spark plugs, leads. i'd also be tempted to advance the timing a couple of degrees to make better use of the unburnt fuel. of course, you dont want it to ping.

i never re-jetted my carby from the falcon jets and i never had a problem with my bumper bar turn black around my exhaust after i tweaked the timing, reset spark gap, etc