Black smoke from tail pipes.

[ohsobad]

One of my Vette comrads owns a 96 coupe with the automatic trans. The car is bone stock, mileage unknown, but I was driving behind it today and from time to time, puffs of black smoke would come from the tail pipes. I figures that it might be a problem with the optispark. Does anyone know of this problem and what is the cure? Thanks for the information.:confused

 

[Rogue]

Sounds like the engine's burning oil.

 

[ohsobad]

Black smoke from tail pipes

Sounds like the engine's burning oil.

Oil burning is blue in color, I thought black was a rich fuel condition?

 

[Vettefan87]

When would it puff? Was it when he was flooring it?

 

[6 Shooter]

Sounds like someone needs to open that baby up just a bit more often.

Later . . . . . .
6 Shooter

 

[Vettefan87]

Sounds like someone needs to open that baby up just a bit more ofter.

Later . . . . . .
6 Shooter

That are my feelings as well.

 

[ohsobad]

When would it puff? Was it when he was flooring it?

While I was behind it there would be two to three puffs at a time. The car was cruising at about 60-70 miles per hour. I thought it might be a sign of incomplete combustion through some problem in the ignition system.

 

[Rogue]

Oil burning is blue in color, I thought black was a rich fuel condition?

Not trying to be a smart ass.

I've never seen blue smoke. Blue flame yes. But blue smoke? Just wondering.

Can you smell burned oil from the exhaust? Does it creat lots of soot around the muffler tips and bodywork near the muffler tips?

 

[74bigblock]

Not trying to be a smart ass.

I've never seen blue smoke. Blue flame yes. But blue smoke? Just wondering.

Can you smell burned oil from the exhaust? Does it creat lots of soot around the muffler tips and bodywork near the muffler tips?

Yep! Oil burn smoke is gray with a blue tint to it. Very different from black sooty smoke (related to poor combustion). It (Burning Oil) usually smells like a burnt piece of $#&^!!

 

[Rogue]

Got it.

Occassionally, I'll see a hint of greyish exhaust in some vehicles, then smell the burnt crap afterwards! Thanks for the education.

 

[C4Tom]

I get that black puff sometimes when I mash the pedal. It is unburnt fuel from too rich mixture. I suppose I should replace the TPS to see if that cures it. I've read (probably on here) that when the TPS gets old, it tends to send the computer incorrect readings. That can cause lean or rich mixture.

 

[oldyeller1969]

One of my Vette comrads owns a 96 coupe with the automatic trans. The car is bone stock, mileage unknown, but I was driving behind it today and from time to time, puffs of black smoke would come from the tail pipes. I figures that it might be a problem with the optispark. Does anyone know of this problem and what is the cure? Thanks for the information.:confused

Had a similar problem with my '95 and it was because of some bad injectors. Mine was a little worse. however. It would flood everytime when I went to start it and I would have to do a "clear flood" to get it to start which really brought out the black smoke until it was running, and then it would send out black puffs of smoke while underway. All caused by unburned fuel. Replaced all injectors and now runs like it's supposed to.

 

[TODD L GRIFFITH]

Any codes? Could be an O2 sensor on its way out.

 

[BlackNBlue95]

I would check to make sure the fuel pressure regulator is not damaged by pulling off the vaccum line to it and checkingfor fuel. something easy to do. I would say to do a fuel system cleaning to clean the injectors and decarbonize the engine.

You could have other issues such as stated before an 02 sensor. Any codes?
-=Rick

 

[vette-dude]

I would run some Seafoam injector cleaner in a fresh tank of gas and then see how it does. Just my $.02.

Randy

 

[oldyeller1969]

Any codes? Could be an O2 sensor on its way out.

There were no codes logged which made it real frustrating. We started with the O2 sensor, the MAF and replaced the Optispark as well as new plugs, and wires, and finally new injectors which cured the problem. Did not do any leakdown checks or anything with the injectors because it was only slightly less cost to test the injectors as opposed to replacing them. Besides that I wanted to go with bigger injectors than stock - it's made a difference.
RT/oldyeller1969

 

[TODD L GRIFFITH]

There were no codes logged which made it real frustrating. We started with the O2 sensor, the MAF and replaced the Optispark as well as new plugs, and wires, and finally new injectors which cured the problem. Did not do any leakdown checks or anything with the injectors because it was only slightly less cost to test the injectors as opposed to replacing them. Besides that I wanted to go with bigger injectors than stock - it's made a difference.
RT/oldyeller1969

I had a 94 C4 Coupe. It really ran nice and I ended up doing alot of work to it. I ended up rebuilding the transmission at about 80K miles. That was probably the only thing unexpected I had to do. It was an automatic. If you flush the tranny after 75k miles, it may start to slip, for anyone with automatics, something to be aware of. Very reliable car I wish I still owned it but traded it for a 99 c5 hardtop FRC. My current vette will be my last brand new one. There are about 4 or 5 other years and types I want. Glad to hear you fixed the problem.

 

[ohsobad]

Thanks for all of the replys, I'll try to help get to the root of this car's problem with your suggestions.

 

[TODD L GRIFFITH]

I wonder how rich you are with larger injectors? You may encounter alot of smell from the converters and alot of black soot in the tail pipe. An easy fix for the LT1 is to get an adjustable fuel pressure regulator, pressure guage and have someone with a dyno, wide band, etc. and tune it. The fuel pressure on a LT1 is 3 bars or 43.5psi I believe from my memory. This way you can dial it in and make alot more power.