what's causing this exhaust smoke?

[moparracing]

When i had my viper dyno'd recently, i noticed smoke out the tail under high rev decels:

[media]http://www.youtube.com/watch?v=X3gOo63GesY[/media]

[media]http://www.youtube.com/watch?v=kujisSsdIko[/media]

my tuner says it's crankcase oil thru the pcv valve & that i should cap it off..... What do you guys think?

 

[plumcrazy]

weird that it is when you let off though

 

[Ratical2]

Not sure what the cause is... just thinking aloud, the smoke seems to be oil due to the blue color. If the smoke was black, I would say unburnt fuel.
If the smoke was continuous for the entire deceleration, I would think it could be the rings but it is only a short period at lift off.
So, it is possible the tuner is correct.

 

[EllowViper]

What do you see during a cold start in the AM? Smoke on a cold start usually valve guides weeping oil. Smoke on hot hard decel/hi vaccum could be valve guides, rings, crankcase vent...or all the above. Basically any area that the hi vaccum can pull oil/vapor into the intake stream. Car sounds great by the way~!

 

[georgethedog]

Blue colored smoke is usually caused by oil. Now, the question is how did the oil get there? It could be caused by the PCV valve. I would replace it (not cap it off) and I bet that is the issue. In any event, I don't think it is a lot to worry about. If it was white... then worry...

 

[Glen97]

I have no idea on the blue smoke but would like to know what your dyno numbers?

 

[moparracing]

car only has 9500 miles on it... i would hope that it isn't worn internal parts.
There is no other smoke any other time. Cold, hot, it seems fine - except for what i describe above. It was only 50 degrees when i dyno'd.

should i consider a catch can? Suggestions?

dyno numbers were:
465 rwhp
540 rwtrq
Belanger headers & a 3" catless magnaflow exhaust with a K&N air filter.

it did run abit lean, my sct tuner (sean roe) is adjusting.

 

[plumcrazy]

what are the mods ?

SCT i assume

 

[JonB]

Look inside your smoothe tubes. Is there oil residue inside, along the bottom? ie from sucking oil-froth/puke into the Throttle Bodies? Check out the PCV lines from valve cover to airbox. Oily?

96-97 GTS had some ideosyncracies, because THE YEAR MATTERS..........

 

[moparracing]

Look inside your smoothe tubes. Is there oil residue inside, along the bottom? ie from sucking oil-froth/puke into the Throttle Bodies? Check out the PCV lines from valve cover to airbox. Oily?

96-97 GTS had some ideosyncracies, because THE YEAR MATTERS..........

what i see is it's fairly clean from the pcv valve line to the intake. The valve covers "t" together on a separate line to the air filter box & there is a slight oily residue in the tubes/TB...

 

[JonB]

Is there any chance your crankcase is overfilled, even very slightly? The oily pecker-tracks in the tubes and TBs are a telltale sign that some frothed oil blow-by is being sucked in during HIGH rpms on the dyno, and/or during hard braking on the street/track. More common in Gen 2 96.5-97 valve covers...and MUCH worse if there is any overfill.........

 

[ViperTony]

what i see is it's fairly clean from the pcv valve line to the intake. The valve covers "t" together on a separate line to the air filter box & there is a slight oily residue in the tubes/TB...

Check the line coming in from CCV orifice that sits atop the block. It t's into the intake directly under the TB's. This is where I found my oil was coming from, not the valve covers. I installed an in-line Air/Oil seperator which works like a charm for me. http://forums.viperclub.org/illustrated-upgrades/641305-my-genii-ccv-air-oil-seperator.html

 

[moparracing]

Is there any chance your crankcase is overfilled, even very slightly? The oily pecker-tracks in the tubes and TBs are a telltale sign that some frothed oil blow-by is being sucked in during HIGH rpms on the dyno, and/or during hard braking on the street/track. More common in Gen 2 96.5-97 valve covers...and MUCH worse if there is any overfill.........

there's a min & a max line with 2 qrts marked in between..... it's filled to the max line.

someone earlier said it might be a bad pcv valve, how can you tell when one is bad? It's not stuck, it rattles when shaken.

 

[moparracing]

Check the line coming in from CCV orifice that sits atop the block. It t's into the intake directly under the TB's. This is where I found my oil was coming from, not the valve covers. I installed an in-line Air/Oil seperator which works like a charm for me. http://forums.viperclub.org/illustrated-upgrades/641305-my-genii-ccv-air-oil-seperator.html

ccv? is that the line that has the pcv inbetween the intake & the top of the motor, from under the intake? did you have smoke out the exhaust like me?

 

[Fatboy 18]

Do you go through much oil?

What about valve guide oil seals?

 

[moparracing]

Do you go through much oil?

What about valve guide oil seals?

none @ all & it's clean.

 

[ViperTony]

ccv? is that the line that has the pcv inbetween the intake & the top of the motor, from under the intake? did you have smoke out the exhaust like me?

Not like you...in other words that never happened to me on the dyno BUT when I brake hard at the track it used to do that. I don't know if that's your problem or not but for me that oil seperator is working very well. I found that oil was not coming from the valve covers but directly from the crankcase orifice. I sent you a PM.

 

[Phun70]

What exhaust system are you running???

 

[Greg Good Cylinder Heads]

Open the throttle bodies and look into the manifold with a bright flashlight to check for oil.

Also, and there is a very odd chance it could be this, but I have disassembled several sets of Gen 2 heads that came in for porting did not have seals on one head. You can check this by pulling the valve covers and visually inspecting.

 

[Slithr]

Mr. Good..... have you always been located in Houston, or is this a recent re-location? Now if Dan @ DC performance would make a good business decision and move from California to Texas With Tomball Dodge we could have a Viper Trifecta right here in Houston

 

[Greg Good Cylinder Heads]

Mr. Good..... have you always been located in Houston, or is this a recent re-location? Now if Dan @ DC performance would make a good business decision and move from California to Texas With Tomball Dodge we could have a Viper Trifecta right here in Houston

Born and raised. Not many of us left anymore it seems.

 

[moparracing]

What exhaust system are you running???

kinda homemade:

http://forums.viperclub.org/2916700-post224.html

 

[moparracing]

Open the throttle bodies and look into the manifold with a bright flashlight to check for oil.

Also, and there is a very odd chance it could be this, but I have disassembled several sets of Gen 2 heads that came in for porting did not have seals on one head. You can check this by pulling the valve covers and visually inspecting.

opened the TB's, pretty clean & oil free... i seem to be getting more oil from the valve cover vents to the drivers side of the air cleaner. That tube & side of the air cleaner had a trail of oil while the other side was dry. The pcv to intake line had some oil, but not as much as the valve cover vents. So, do i just need an oil catch can on valve cover vent lines or both or neither & what do you suggest?

 

[Jack B]

opened the TB's, pretty clean & oil free... i seem to be getting more oil from the valve cover vents to the drivers side of the air cleaner. That tube & side of the air cleaner had a trail of oil while the other side was dry. The pcv to intake line had some oil, but not as much as the valve cover vents. So, do i just need an oil catch can on valve cover vent lines or both or neither & what do you suggest?

Run both valve covers to a catch can from front of the valve covers. Also remove the PCV valve and run that line into the above noted line. You will have two tees up front. That solves both the vacuum/oil draw issue through the pcv valve and the excess oil in the valve covers. Simple,clean and only one can is needed. You can also replace the oil fill plug with a breather, allowing the engine to exhale better.

Your car is blowing smoke on vacuum, but, shows no smoke under load, the odds are it is the PCV system, the above method should fix the problem, if not, it is mechanical and a more serious problem.

 

[Greg Good Cylinder Heads]

opened the TB's, pretty clean & oil free... i seem to be getting more oil from the valve cover vents to the drivers side of the air cleaner. That tube & side of the air cleaner had a trail of oil while the other side was dry. The pcv to intake line had some oil, but not as much as the valve cover vents. So, do i just need an oil catch can on valve cover vent lines or both or neither & what do you suggest?

JackB and Tony have summed up how to set up the breather/catch-can pretty well. The only thing I would add is.......if you want to keep things EPA compliant then you can vent the catch-can back to the airbox. The catch-can will be just an oil separator.

One other thing I have heard mentioned about smoke on decel is the tune being rich when the throttles are closed but the engine is still turning some rpm, and rinsing fuel off the cylinder walls. I'm not a tuner so I don't have personal experience with this, but it's food for thought.

 

[plumcrazy]

if you exhaust into the airbox it will lower your octane, change your A/F and give you a higher chance of detonation.

doubt its going to be anything too bad as the factory does do this on a lot of cars

 

[Greg Good Cylinder Heads]

if you exhaust into the airbox it will lower your octane, change your A/F and give you a higher chance of detonation.

I was just mentioning it, *if* someone was worried about pollution.

Assuming the catch-can removes all of the oil vapor from the blow-by, it *should* be ok to vent the blowby back to the airbox after it leaves the catch-can, but we all know how *would of - should of - could of* goes.

 

[moparracing]

One other thing I have heard mentioned about smoke on decel is the tune being rich when the throttles are closed but the engine is still turning some rpm, and rinsing fuel off the cylinder walls. I'm not a tuner so I don't have personal experience with this, but it's food for thought.

actually, it was too lean, almost 14.5.....

i want to come up with either an air/oil separator or just a catch can before i dyno again with my revised tune to see my improved A/F & if it help's the decel smoking.

I've heard/seen a few ideas for separators/catch can's, anyone else got one that works well?

 

[nutkees]

Anyone has a nice write up on how its done with pics etc??

I think I got exactly the same problem, see this vid:
@ 2:30

[media]http://www.youtube.com/watch?v=aOEXytj4T8A[/media]

 

[Fatboy 18]

I too have had some smoking issues from time to time, after reading through some of the posts on here I checked my throttle body's and have found a fair amount of oil covering the intake butterflies. I guess I need to sort out a puke tank of some kind too