Shmokin'

sab · Postby **sab** » Thu May 11, 2006 11:18 pm

Car's been running like a dream, but over the last few mornings I've been noticing a fair bit of black/grey smoke coming out of the exhaust on slightly spirited take off from the lights.

With the darker mornings, it's been pretty obvious when the car behind me has its headlights on.

What could be causing this smoke? (And no. It aint tyre smoke!) :mrgreen:

Car's a 1.8 NA that has around 130k on the clock. Running irridium plugs and magnecore 8.5mm leads. o2 sensor and injectors were replaced not long ago.

Any idea's?

irwin83r · Postby **irwin83r** » Thu May 11, 2006 11:24 pm

hope its nothing major my 1.8s around 130k also :shock:

dark smoke? thats oil or excess fuel isnt it?... white being water

if it only happens when u give it a boot.. would think fuel.. but o2 and injectors are new you say?? sure you got 02 sensor wired in correctly??

temp sensor??

just some thoughts

maxwolfie · Postby **maxwolfie** » Fri May 12, 2006 12:08 am

blue/black/white?

sab · Postby **sab** » Fri May 12, 2006 1:27 am

Smoke colour is grey/black. o2 sensor wired up ok.

I'm suspecting something like oil or fuel, but no idea how or what's causing it.

Moggy · Postby **Moggy** » Fri May 12, 2006 7:39 am

Oil is generally a blue colour. White usually means coolant. Black smoke sounds like it is running a bit rich on throttle and is generally not much of a problem (almost every modified turbo car I have seen puts out some black smoke on boost). Maybe as it is quite cold in the morning this time of year your car is putting in too much fuel when you floor it. If you are putting in full throttle I think the ecu goes to open loop and disregards the O2 sensor. The ecu would then use airflow and air temp only to measure fuel.

In short, if there isn't heaps of smoke, I wouldn't worry too much...

PT · Postby PT » Fri May 12, 2006 9:10 am

Fuel... I wouldn't worry.

Rich is safe.

jules · Postby **jules** » Fri May 12, 2006 11:53 am

When did you last flog it to the limiter??
Malibu has smoked like that once when I didn't drive for a while.

If you're not hitting the limiter once a week, then you're not cleaning out the cobwebs.

Jules

sabretooth · Postby **sabretooth** » Fri May 12, 2006 2:21 pm

Generally:

Black is fuel, and indicates that your motor is running rich.
White is oil OR coolant. You will be able the smell the difference.
Blue is definitely oil

How bad is the smoking? If you get out of the car to have a look, can you see the smoke?

Does it only happen when the engine is cold? Does it only happen in cold weather?

sab · Postby **sab** » Fri May 12, 2006 3:13 pm

Thanks for the responses so far guys!

I drive into town for work daily, so lots of start / stop driving.

Cob webs usually get cleaned out every couple of days, but generally 1st and second gear stuff only.

More noticable when air temp is cold rather than warm. Doesn't smoke on idle or on 1st start up in the mornings.

Due for an oil change soon, so don't know if that has anything to do with it. Also running full 2 1/4 exhausts with extractors and high flow cat. Mania CAI and big ass, 3 inch intake tube to inlet manifold.

Tending to think more towards an over fueling issue and very slight oil burning.

Fuel economy has dropped off slightly, but still getting around 400k's to a tank.

Postby **Okibi** » Sat May 13, 2006 2:55 am

My vote is for valve stem seals too

Moggy · Postby **Moggy** » Sat May 13, 2006 10:21 pm

SLash wrote:If you sitting at idle and then boot it and it smokes a lot, then it could be your valve stem seals. Easiest way to check that is fund a big hill, coast down the hill, letting the hill rev the engine to about 3k ish in 2nd, when you get to the bottom, boot it. If theres a lot of smoke, it's probably stem seals.
-B

This is exactly what my mx has been doing! What do you have to replace to fix this? Is it much of a job? (Thread hijack in progress... :roll:

)