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2G Smoke after hard pull

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polverari

5+ Year Contributor
102
15
Jan 29, 2018
São Paulo, South_America
Hello!
As usual on my topics, I apologize for any mistakes. English is not my native language.
I found some posts similar to mine, however, I found none that reported a problem identical to mine and the doubts I have.

I have a GST 2.3 (Stroker) with an FP 68HTA

The engine was recently made by myself and I can report anything you want to know.

Recently, the car started smoking on only ONE specific occasion: after WOT, ok the peak pressure, when I take my foot off the gas, the car releases a quick cloud of smoke (which I see in the rearview mirror and can smell)

The smoke actually appears to be from burnt oil. (Wide shows rich for less than a Second, when i Hear the blowoff. I dont think this smoke os from fuel...)

The car does not burn oil when idling, neither hot nor cold, nor moving normally, neither first or second gear (1.0@boostcontrol). The only occasion is: after hard pushing, WOT, after 5000rpm .. 1.7bar .. when I release the accelerator, the cloud of smoke comes out. The cloud lasts for a second and soon after I touch up the throttle It stops.

If I want, I can continuously accelerate up to 7200rpm, with no smoke coming out. Just after taking my foot off the throttle

Everything was done: valves, guides, seals, engine block, forged pistons and rods, oem or performance parts.

The turbine oil supply comes from the head, without restrictor.

Would any of you have any suggestions? If some information is needed i can Tell you: timing (i made the map), fuel, etc
 
I suspect that it may be a rich condition - the MAF has already measured air that went past it, but the throttle snaps shut, and the extra fuel will be burned off, which would be a grey cloud.
 
This is where I was going with those questions.

I figured haha. My car would not put out any smoke at all under boost, but as soon as you closed that throttle after a pull whoever was behind could not see a damn thing through all the blue smoke LOL. I didn't run a catch can for 6 years at 30psi with no issues. Then out of the blue one day my car decided it needed one.

I thought for sure I cracked a ring land, blew a valve seal or something of those likes.It was not something that got progressively worse, It just came out of nowhere. But the leakdown and compression check looked good and its been fine the last 2 years as long as I have the catch can in.
 
If you have a vented blow off valve it could be smoke from going rich when letting off of the throttle, do you still have a factory mass air sensor or is it speed density converted?
 
I suspect that it may be a rich condition - the MAF has already measured air that went past it, but the throttle snaps shut, and the extra fuel will be burned off, which would be a grey cloud.

ITS possible!
Oh, btw, im not using MAF, um using SD
 
Indeed, get someone to watch or set up a stationary camera to record the plume so you can analyze its colour, blue vs grey, white, or black.

I Will do this tomorrow ir thursday! I Will post the vídeo gere!
 
Sounds like blow by to me. I had the same issue arise and ended up fixing it by installing a catch can.

Nice to Hear!
Btw, you used one or two oil catch cans? Can you tell me where did you connect It? I mean... PCV-CATCH // SIDE NIPPLE- CATCH? With a 3-port-catch?
 
I figured haha. My car would not put out any smoke at all under boost, but as soon as you closed that throttle after a pull whoever was behind could not see a damn thing through all the blue smoke LOL. I didn't run a catch can for 6 years at 30psi with no issues. Then out of the blue one day my car decided it needed one.

I thought for sure I cracked a ring land, blew a valve seal or something of those likes.It was not something that got progressively worse, It just came out of nowhere. But the leakdown and compression check looked good and its been fine the last 2 years as long as I have the catch can in.

Wow ... After this text, I think I will provide an oil catch can as soon as possible, because what I LESS WANT IN LIFE is having to open the engine again to mess with something related to the rings or something like that.
 
If you have a vented blow off valve it could be smoke from going rich when letting off of the throttle, do you still have a factory mass air sensor or is it speed density converted?

Its SD converted!
 
(I just realized that I could have answered everyone in one comment, but ok)

I have a question: if the problem is the blowby issue, shouldn't I be seeing smoke during all the acceleration? Because... Are the gases passing from the combustion chamber to the bottom of the engine?

if I only notice the smoke when I stop accelerating, valve retainers can be the problem? in that case would i have to reduce the crankcase pressure? and how could i do that? the installation of oil catch can seems to work as a oil filter, but not as something that helps the ventilation of the crankcase
 
(I just realized that I could have answered everyone in one comment, but ok)

I have a question: if the problem is the blowby issue, shouldn't I be seeing smoke during all the acceleration? Because... Are the gases passing from the combustion chamber to the bottom of the engine?

if I only notice the smoke when I stop accelerating, valve retainers can be the problem? in that case would i have to reduce the crankcase pressure? and how could i do that? the installation of oil catch can seems to work as a oil filter, but not as something that helps the ventilation of the crankcase
No. A catch can is exactly what helps with crankcase venting. That's its whole purpose. The can exists so you dont suck oil. otherwise we would just run some big lines from the valve cover to the intake pipe
 
The PCV valve acts like a variable check valve. When there's more pressure in the intake manifold than the crankcase, it prevents that pressure from entering the crankcase like a one way check valve. When you close the throttle, the intake manifold will be under vacuum, especially if engine braking, and the valve will open fully to clear the crankcase vapors. Under light throttle cruise the PCV will be partially open in instances where there is more crankcase pressure than boost pressure in the intake manifold.
 
No. A catch can is exactly what helps with crankcase venting. That's its whole purpose. The can exists so you dont suck oil. otherwise we would just run some big lines from the valve cover to the intake pipe

I apologize, but there is a point that I still don't understand:
If the smoke only appears when I stop accelerating, it means that this oil is passing through the valve seals, right?
So, if I put an oil catch can I will prevent the oil from going into the intake, but I will not decrease the internal crankcase pressure (which will remain the same).
Am I thinking right or am I forgetting something?
 
The PCV valve acts like a variable check valve. When there's more pressure in the intake manifold than the crankcase, it prevents that pressure from entering the crankcase like a one way check valve. When you close the throttle, the intake manifold will be under vacuum, especially if engine braking, and the valve will open fully to clear the crankcase vapors. Under light throttle cruise the PCV will be partially open in instances where there is more crankcase pressure than boost pressure in the intake manifold.

Ooh.. Now I understand what you mean...
So, I must place an oil catch can in the way: PCV-Intake Manifold...
BTW, i've seen into the small hose that goes PCV-IM and there is nothing about excess of oil... oil.. or something...
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Last edited:
Think of your pcv valve as a balancer that balances crankcase pressure with intake manifold pressure, when one is higher it tries to balance them.
 
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