1996 Cadillac Seville SLS Smoking when starting engine

NRIVERSIII

MEMBER
1996 CADILLAC SEVILLE

1996 Cadillac Seville SLS bought it in May 2007 with 84,000 miles and it ran great. Last month I started to notice that when I start it black smoke comes out of the exhaust and then it would run fine. Now, my wife tells me she sees smoke come out of the exhaust when I am driving in front her when I accelerate. Now, I notice that there is puff of smoke almost each time I start it. I checked this car really good when I purchased it and it did not smoke. It runs great and the gas mileage is pretty good for this Northstar engine. About 22 mpg on the interstate.

What should I do to check this out and get it fixed, reasonably?

5 Replies

MERLIN2021

MECHANIC
17,250 POSTS

Black smoke is a mixture proble, running too rich, it's either gonna be 02 sensor related or temp sensor, possibly the Mass air flow sensor. Any codes? When you start it is it always black smoke?

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Sunday, September 23rd, 2007 AT 5:44 PM

NRIVERSIII

MEMBER
4 POSTS

Yes, it always black smoke never steam or white smoke. I also notice that it uses more oil than it did when I first got it in May, 2007.

Where should I get it checked?

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Monday, September 24th, 2007 AT 2:15 PM

BUZZSAW

MECHANIC
1,198 POSTS

Sorry guys its just heavy carbon build up, the car needs blown out, stomp it to the floor a few times, seen it many times, as far as the oil usage, again carbon, pull out the plugs, after warming up the motor, and dump top engine cleaner into cylinders, let sit for 4-6 hrs, turn engine over with plugs out, blowing out cleaner, it is messy and you will see chuncks of carbon, cover engine with plastic before turning over, reinstall plugs and wires and hose off, change the oil, it will smoke badily at first but it will be fine ( I was a group leader at Cadillac) I know this problem well

prob is premium gas causes carbon build up for granny drivers, got to stomp on the gas in a cadillac and blow it out

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Tuesday, September 25th, 2007 AT 1:05 AM

NRIVERSIII

MEMBER
4 POSTS

Buzzaw,

Thanks. Your suggestion seems like a good idea and the solution sounds very likely. I will blow it out today. Also, I noticed this morning that the smoke is not always black but comes out kind of blue or gray as well. Do you think that is still carbon build up.

Should I find a good mechanic to clean the plugs and treat the engine with cleaner? How about a tune up? Or at least new plugs?

Thanks

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Tuesday, September 25th, 2007 AT 12:31 PM

BUZZSAW

MECHANIC
1,198 POSTS

Depends on the plugs, platiums last 100000 mil, me personally would also put wires on at this time, 90k
dont buy cheap ones, again auto zone parts just dont last