Exhaust Smoking..

[Easy Tiger]

Hey guys

I've had this problem for a while and I don't know what's causing it. My v35 is smoking from the exhaust under any sort of load. The fuel economy is bad as well which could be related but I can't find the actual problem.

- I have had the o2 sensors replaced as they had failed

- it is not burning oil

- it is not losing coolant and there is no cross-contamination of oil and coolant

- it does not overheat

- fuel economy is bad but I suspected fouled injectors

Anyone got any ideas? Could it be carbon deposits getting blown out the exhaust when a bit of pressure is put through the system? I've had the intake cleaned out already but I guess it could be residuals in the engine and through the exhaust system?

[whtbox]

what colour of smoke?

[Easy Tiger]

It appears to be black but I really can't tell. If it were blue or grey I would be losing oil or coolant but I'm not losing either of those as above.

[rex2ce]

Air cleaner or bad fuel?

[Easy Tiger]

Not the fuel been happening for many months and not the air filter either, replaced it when I had the intake cleaned out (which was filthy black).

Thanks for the responses so far, please keep them coming as I really want to get to the bottom of this.

[Daleo]

An interesting one, if you've done o2 sensors but you're still using loads of fuel, maybe a crank angle sensor issue? Don't know what VQ's are like in this area, but several other Nissan's I've owned in the past have killed crank angle sensors and the effect on economy is terrifying. You should pick up a crank angle on diagnostics though.

Also what colour is the smoke? As a general rule, fuel or an over rich condition will be black smoke. If you have a dodgy pcv you could be getting oil vapour, but you would be losing oil (a bit) and you'll get grey or white smoke, but idle quality also suffers.

Hope you solve the issue, Dale

[Easy Tiger]

Thanks Dale. I think the smoke is black, but no error code is coming up for the crank sensor.

Interesting comment about the pcv and the rough idle, it has an intermittent rough idle but again I originally put this down to fouled injectors. But it doesn't appear to be burning any oil or if it is, a very small amount that I'm not overly noticing.

Thanks guys please keep the ideas coming.

[rs73]

on cold mornings my car would blow billowing white smoke @ traffic light, that much up to a level it's quite embarrasing like I'm some american Apache / Sioux indian chief trying to send a smoke signal to a neighbouring village...

it goes on till the car well warmed up a bit. same case? or just a normal case of having too much water vapour in exhaust?

car is garaged

[g33k]

I know you said not oil, did you check HOW MUCH oil you have? is it low by chance?

Get that dipstick out baby!

+1 for water vapour, that passes.

[Easy Tiger]

I know you said not oil, did you check HOW MUCH oil you have? is it low by chance?

Get that dipstick out baby!

+1 for water vapour, that passes.

Nah I regularly check the dipstick to make sure the oil isn't low. It's almost 5000km since the last service and it is at the top of the high mark, so I really don't think anything relating to oil is the problem.

I guess water vapour is a possibility but it appears to be a very dark plume of smoke not white or grey. It hangs around long after warming up, ie I can take it for 30 mins up the highway, turn around and floor it back down the onramp and a massive dark plume of smoke will appear behind me, really quite embarrassing. It's got me beat which is why I've now asked here, I am out of ideas.. It's anytime I plant the foot a bit or go up a hill where the engine is under load, not when cruising. I am stumped.

Edited December 8, 2009 by Easy Tiger

[V35_Paul]

It's fuel for sure then.

Go to your mechanic and get someone who knows what to do and get it fixed.

[Easy Tiger]

It's fuel for sure then.

Go to your mechanic and get someone who knows what to do and get it fixed.

Yeah I think so too but my mechanic keeps blaming it on carbon deposits being blown out but I'm not sure it is.. Which is why I posted here. Thanks all for the responses. I was hoping someone might have had this problem and fixed it.. Unfortunately seems not but still hoping someone might know the magic bullet fix

[V35_Paul]

Have you opened your manifold and looked inside? It might be realy dirty and your throttle body.

[whtbox]

btw you can try use Seafoam.

Heard it's a good stuff in USA. but not sure where you can get it in OZ.

[Easy Tiger]

Have you opened your manifold and looked inside? It might be realy dirty and your throttle body.

Manifold yes, TB no.. Would it likely be that?

[g33k]

Nah I regularly check the dipstick to make sure the oil isn't low. It's almost 5000km since the last service and it is at the top of the high mark, so I really don't think anything relating to oil is the problem.

OK, but just for the record, i had mine serviced, with full Purple Oil @ 40,000km not long back, its now hit 45K and i noticed a random smoke.... checked my engine oil and i had about 1L.........

In saying that i don't have oil leaks..... (manual)

But, if you've checked, you've checked!

Good luck bruv! =)

[V35_Paul]

Manifold yes, TB no.. Would it likely be that?

If the manifold is clean then i'm guessing no. How's your idle? is it between 650 and 750rpm? if it's a rough idle then maybe a T/B reset or a ECU reset.

I still think it's fuel burning.

Have you put injector clean in your fuel? might help a little.

[Easy Tiger]

If the manifold is clean then i'm guessing no. How's your idle? is it between 650 and 750rpm? if it's a rough idle then maybe a T/B reset or a ECU reset.

I still think it's fuel burning.

Have you put injector clean in your fuel? might help a little.

Yeah I put through two lots of injector cleaner not long ago too.. Tried everything!

The idle is rough intermittently but in terms of rpm range it is normally spot on.

Thanks for the help guys really appreciate it, just a shame I can't get to the bottom of this.

[Stephen Thorpe]

is your rocker cover oil vent hose blocked?

Crankcase breather hoses that go back to your manifold...

[mellowman]

My money is on the injectors are fouled....