Cadillac Owners Forum banner

1 - 17 of 17 Posts

·
Registered
2016 XTS FWD Platinum
Joined
·
1,084 Posts
Discussion Starter #1
I was driving my 98 STS today and I came to a stop light. I was turning right as the oncoming traffic started to go but I knew I could easily beat them! :) As I stomped on the gas, the car took off as usual but there was a cloud of black smoke behind me! :( I just recently changed the plugs, wires, air filter, fuel filter, and the PCV valve. What would cause all the black smoke?

Max
 

·
Registered
White Diamond 2001 STS
Joined
·
1,317 Posts
Max, how often do you tromp on it? If not often enough, that "smoke" might be carbon burning off, although it probably wouldn't be a dark black smoke like you're talking about. Oil is usually blue and too much gas is usually brown.

What symptoms were you correcting when you put on all those new parts? Was anything wrong with the car before all that work? I might suspect one of those new parts might be faulty, although I wouldn't really know which one to say. I've never seen black smoke out of a car before.

Are you sure it was from your vehicle?
 

·
Registered
2016 XTS FWD Platinum
Joined
·
1,084 Posts
Discussion Starter #4
Jason,

I'm definately sure that it was from my vehicle. I was so embarassed! I probably haven't "tromped" on it lately as much as I used to. I changed everything because sometimes in the morning, the car will idle rough for a few seconds and then smooth out. It only does it occasionally and I thought changing the plugs would help but it didn't. Someone suggested it might be a fuel pressure regulator but I've been hesistant to take it in. I've been hoping the problem might become more regular because I know if I take it in, the car will act fine and they will look at me like I'm crazy.

What do you think?

Max
 

·
Registered
2016 XTS FWD Platinum
Joined
·
1,084 Posts
Discussion Starter #5
Jay,

I haven't replaced the O2 sensors. Won't they send a code if they go bad?

Max
 

·
Registered
White Diamond 2001 STS
Joined
·
1,317 Posts
Max, it sounds to me like a fuel-related problem. Does it still idle rough in the morning? Only while cold or all the time at idle? I'd get a pressure gauge and test the fuel pressure as you start the engine. It may be out of spec. The regulator is fairly easy to replace -- you may have a leaking regulator which is allowing raw fuel into the intake manifold, accounting for the smoke and rough idle. Pull the vacuum line coming out the side of the regulator and see if it's wet with fuel. If so, that's your problem (a leaking regulator).

Good luck,
 

·
Registered
Joined
·
2,235 Posts
If you haven't "gotten on it" in a while It's probably OK Try getting on a few more times and see if it clears up. You'd be surprised how much stuff it'll blow out if you don't hit it for a while and then do. If it runs good otherwise I wouldn't worry about it.
 

·
Registered
Joined
·
3,683 Posts
Maximln said:
Jason,

I'm definately sure that it was from my vehicle. I was so embarassed! I probably haven't "tromped" on it lately as much as I used to. I changed everything because sometimes in the morning, the car will idle rough for a few seconds and then smooth out. It only does it occasionally and I thought changing the plugs would help but it didn't. Someone suggested it might be a fuel pressure regulator but I've been hesistant to take it in. I've been hoping the problem might become more regular because I know if I take it in, the car will act fine and they will look at me like I'm crazy.

What do you think?

Max
does it idle rough severely on cold start? because that happened to me because car was misfiring due to the bad spark plug/wire sets.
 

Attachments

·
Registered
2016 XTS FWD Platinum
Joined
·
1,084 Posts
Discussion Starter #9
It only runs rough for a few seconds when the car is cold and then clears up after a few seconds and runs fine once the car warms up. If it sits all day, it will sometimes do it again even if it's warm outside but when the engine is cold. I don't think it's a bad plug/wire set just because it did the same thing before I changed it. The car still has a bumper to bumper warranty but I was just hoping it would do something more regularly rather than just for a few seconds. Do you think the techs can still figure it out?

Max
 

·
Registered
White Diamond 2001 STS
Joined
·
1,317 Posts
Well, proper diagnosis is the key to fixing any problem. If you leave it overnight with them and give them specific instructions to put a fuel gauge on it and watch the fuel gauge when they're starting it in the morning, they might be able to see if it's a fuel pressure problem.

The key is to find a set of mechanics that can follow directions. My dad had a cold start problem with his Ford truck. Only when it was 30 or below or something outside, the starter wouldn't even turn. Completely dead. When the sun came out and warmed it up, it'd start. He'd take it to the dealership and they'd put it in the garage overnight (where it's warm) and, duh, could never replicate the problem. It took him almost a year of traveling around (my parents are full-time RVers) to find a dealership who actually listened to the customer and made an attempt to try to replicate the problem (it was a faulty power switch on the transmission...if the transmission didn't power up, it would never activate the P/N switch to enable the starter circuit).
 

·
Registered
Joined
·
3,683 Posts
here is what was happening to my car before
On cold start(meaning starting the car after few hours of prior operation), it will idle very rough and then problem goes away in few min. Dealer told me that it was just a carbon buildup and did the spark wire/spark plug change. Few days later i felt the misfiring again. When the ses light came on, i took it to autozone and had it read using obdii scanner, and it said that car's cylinder # and # was misfiring and some sensor heater problem. I took it to the dealer and told them that it's still misfiring. I got the car back and it was still funky so i called cadillac (the company not the dealer) and had the dealer come pick up the car from my house and look at it more carefully. and they found that i had a blown head gasket and they did the repair on it well as another spark plug change. Now it doesn't have any rought idle on cold start.

PS. blown headgasket was caused by the overheat which is the result of leaky water pump which was replaced by the dealer last summer and the overheat problem started just around that time.
funny thing is it took me to find out what it was instead of close to 20 visits to the dealer. Now they are on fire and they even offer to pick up the car from my house to check on the oil consumption issue that started after overheating with a factory technician.
 

·
Registered
53 Eldo, 54 CDV, 74 FWB 96 FWB (sold),1998 STS(sold), 03 ESV
Joined
·
755 Posts
kcnewell said:
If you haven't "gotten on it" in a while It's probably OK Try getting on a few more times and see if it clears up. You'd be surprised how much stuff it'll blow out if you don't hit it for a while and then do. If it runs good otherwise I wouldn't worry about it.
I agree. I knew a guy who bought a 97 STS that was owned by an old man who never drove quickly. He had black coming out all the time when he got on it. A few drag races fixed that problem.;) :cool:
 

·
Registered
Joined
·
3,683 Posts
Katshot said:
I don't think Max's problem has anything to do with his not "blowing it out" enough. If you see black smoke at the exhaust, you're burning some extra fuel, period.
Blue smoke = oil
white smoke = water
if it's giving out black smoke all the time then i agree
if this was one of those one time deal then i don't agree.
 

·
Registered
2005 CTS-V, 1994 Infiniti Q45
Joined
·
7,658 Posts
I agree with devil. When i first got my Q, when i would rev it up i would get little clouds of smoke. But now I dont.
 

·
Registered
2016 XTS FWD Platinum
Joined
·
1,084 Posts
Discussion Starter #16
Thanks for everyone's replies. I guess I'm just fighting having to leave the car overnight at the dealer. I'll miss it! :halo: They will give me a 2003 Deville for a rental.

Max
 

·
Registered
Joined
·
2,235 Posts
Look at the bright side......I'm trying to think of one! Oh! Here it is. The dealers shop will most likely screw it up worse than it already is!......Wait that's not a bright side. Maybe there isn't a bright side after all!
 
1 - 17 of 17 Posts
Top