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Well I have had my saab for about a year n half now. Its a 1994 900S V6 (non-turbo duhh) with 189K miles. Mostly, practically all highway miles.

Here is my delima,

It smokes at idle and only at idle. It seems to run a little rough, but barely noticable, not a miss but maybe leading up to one. The smoke is a white(ish) gray color and is barely noticable until I come to a stop or just sitting there idling. It has a pungent odor, doesnt smell like oil or antifreeze, and because of the color I have mix'd feelings on what it is. I do smell a hint of unburnt gas in the odor as well. I noticed within the last 2 weeks, thats when it started to smoke, that my MPG have dropped by 6 miles, I was getting around 33-34 and now I am getting 27-28 mpg.

Anyone have any ideas what it may be?

I been told head gasket
I been told spark plugs/wires or get a tune up

I havent noticed oil in the antifreeze or antifreeze in the oil either and believe me I have been looking.

Anyways, any help will be appreciated.

Thanks

Chris
 

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I would send an oil sample in for a used oil analysis (UOA), pronto. It is only about $20-25, you get the results back in a week by email, and it will tell you exactly if there is something funny going into the oil.

see for example http://www.blackstone-labs.com

Burned anti-freeze does not always smell like what it is. A drop in mpg usually means the fuel/air mix is too rich, which can happen when the front O2 sensor starts to fail, but also for other reasons.

At that mileage, it could just be worn rings and blow-by in the engine, or one cylinder not firing right at idle and gas vaporizing in the catalytic converter. A compression test would tell you if there is a problem with a specific cylinder... beyond that, someone else will have to take this one, since I do not own a V6...
 

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This applies to all and any engines, particularly those close to rebuild time..

full tune up
oil analysis - damned good idea !!
 

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I would check, in order of importance

Ignition leads from coilpack to plugs
Plugs - remove all 6 - look for sooty ones
Coilpack - make sure it fires the plugs - likely it isn't firing the sooty one. See if you put a different plug wire and plug if it will fire that one or not
Oxygen sensor - make sure it looks good, maybe replace it with generic one

If you want to do a test, take the car on the open road and do a top-speed run. Top speed on a V6 should be approximately 140 miles per hour. Obey all state and local speed limits of course, nudge nudge wink wink.

It appears to be a very rich running, perhaps even misfiring. Really the O2 and the coilpack seem to be the bad points. If you haven't replaced the O2 sensor yet, you should, cheap insurance - if it runs great then pat yourself on the back. If not check the coils.
 

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Just remeber that you have two (2) O2 sensors! Front and back cylinder banks.


I would try the suggestions given above. You should basically perform a regular tune up, and do some checking of other things. One that has not been mentioned is to pressure check the coolant system.

Definately do the spark plugs (how old are they?) if they are old.

Tboy
 

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Hi - I worked at the V6 plant for years carrying out durability tests and warranty, A couple of weeks ago I did a head gasket on a V6 which had the same symptoms as yours - white smoke pouring out of the exhaust - the car had covered just over 100k and had recently overheated due to a rad hose coming off.

One tip to check - remove the coolant tank pressure cap and secure a small plastic bag over it with an elastic band - run the engine and if the the gaskets are shot the bag should inflate due to combustion gasses entering th e cooling system.

We have done loads of work on V6 engines and have found that the head gaskets fall apart on removal at around 100k -

The above job was repaired by just replacing the head gaskets (no damaged done to the cyl heads)- it did smoke for an hour after start up due to the amount of coolant that had entered the exhaust system - but this soon evaperated.

Do not pressure test an engine that you suspect as being a head gasket failure - all you do is end up will coolant in the oil!!!!!

Tune up!!! nothing to tune on these engines everything is fixed!


chrisaa said:
Well I have had my saab for about a year n half now. Its a 1994 900S V6 (non-turbo duhh) with 189K miles. Mostly, practically all highway miles.

Here is my delima,

It smokes at idle and only at idle. It seems to run a little rough, but barely noticable, not a miss but maybe leading up to one. The smoke is a white(ish) gray color and is barely noticable until I come to a stop or just sitting there idling. It has a pungent odor, doesnt smell like oil or antifreeze, and because of the color I have mix'd feelings on what it is. I do smell a hint of unburnt gas in the odor as well. I noticed within the last 2 weeks, thats when it started to smoke, that my MPG have dropped by 6 miles, I was getting around 33-34 and now I am getting 27-28 mpg.

Anyone have any ideas what it may be?

I been told head gasket
I been told spark plugs/wires or get a tune up

I havent noticed oil in the antifreeze or antifreeze in the oil either and believe me I have been looking.

Anyways, any help will be appreciated.

Thanks

Chris
 
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