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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
 
It's also generally not where people place the catch can. There is a factory vent from the valve cover to intake tube. Many people add fittings and bigger lines and of course a catch can in the middle to catch oil. There are also vendors that sell vented oil caps with AN fittings
 
It's also generally not where people place the catch can. There is a factory vent from the valve cover to intake tube. Many people add fittings and bigger lines and of course a catch can in the middle to catch oil. There are also vendors that sell vented oil caps with AN fittings

Yes
Im thinking to place the can between PCV and IM because the smoke is seen when i release the throttle...
But if its common to place it between VC and intake, i Will try this first

I Will do the tests today
 
I read before i post this
And i still dont understand why place a can between VC and intake if the smoke is when i release the throttle (vacuum)
Vacuum = pcv open to IM, not?

Yes.
Crankcase pressure builds while doing a pull
You let off the throttle and there is then vacuum in the intake manifold
PCV opens and dumps all the crankcase gases into the intake manifold along with a bunch of oil
Your car burns it and produces smoke.

Run your PCV valve to a catch can. You can either vent it to atmsophere or plumb it back to the intake.
 
Just run a dual catch can setup and be done with it. You save your intake pipe/inter cooler from being coated in oil and also keep oil out of your intake manifold/cylinders.
 
Updating:

Tried catch can in PCV-IM and VC-INTAKE
Same problem.

Maybe the problem is my 68hta. Sad. 25.000 miles with 16psi and driving like a grandma, im only using it properly right now. I'm very upset
 
This is a sealed can? Are you using a stock turbo drain? I've seen really bad setups that dont drain well.
Yes, a sealed Cam.
I dont know about the oil drain. I guess its not oem but i will post a pic here in 5 hours!
 
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Turbo seems ok, i cant move the shaft in direction: right car wheel - left car wheel, but o can move a little in direction: front of the car, rear of the car
Can seems working
Some oil near turbo entry
No oil in Spark plugs, nothing
I Will try to post the pics
 

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Updating:

Tried catch can in PCV-IM and VC-INTAKE
Same problem.

Maybe the problem is my 68hta. Sad. 25.000 miles with 16psi and driving like a grandma, im only using it properly right now. I'm very upset

did your pcv-im route include a check valve oriented in the right direction? that is, allow pull from crankcase to intake manifold, disallow flow from manifold to crankcase
 
UPDATING:

I disconnect PCV-INTAKE MANIFOLD hose.
I disconnect VALVE COVER - INTAKE hose

Problem is solved, for my lucky, the problem was blow by.

Now i'll just let both ventilating to the atmosphere.

Well.. tomorrow i will do more 2,3 pulls, just to get sure.
 
did your pcv-im route include a check valve oriented in the right direction? that is, allow pull from crankcase to intake manifold, disallow flow from manifold to crankcase

(The OEM PCV do this. Or not?)
 
they do if you use the oem pcv valve, though they are known not to be the best of sealers when in closed position, especially when theyre older.
wasnt immediately clear if you were still using the stock valve.. some replace with the nipple that goes to the brake booster and forget you want the crankcase sealed against boost pressure.

you said the smoke is white, though, correct?

youre not running two open ports now, are you? intake pre-turbo and manifold?
 
This is a sealed can? Are you using a stock turbo drain? I've seen really bad setups that dont drain well.

I got confirmation from fp that the stock drain is sufficient for 68hta.
 
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Turbo seems ok, i cant move the shaft in direction: right car wheel - left car wheel, but o can move a little in direction: front of the car, rear of the car
Can seems working
Some oil near turbo entry
No oil in Spark plugs, nothing
I Will try to post the pics

Is that much blow by normal?
It seems a bit excessive to me with the pcv being good.
I’m also surprised with it pooling that the spark plugs are clean still, seems like something is leaking more pressure into the case making it put out that much.
 
You really need to do some research on how a catch can works. I'm willing to bet the way you have it set up is incorrect or the can does not have baffles. I can explain it but its going to be hard if you have read the PCV article and still don't understand.

I have two 10 AN fittings welded on my valve cover and route the lines to a catch can. Then the top port that is above the baffles inside the can goes to my air intake pipe. 3 ports total on my can. The pressurized air and oil mix go into the side of the can from the valve cover. The oil is separated from the air inside the can by a material that is inside of the can under the baffles. Well just say steel wool as an example. Then the clean air is recirculated into my air intake. The air intake also creates a vacuum to help draw the pressure out of the crank case. If you don't have the material, or baffles in the can to separate the air and oil, you are just sucking oily air back into the air intake, thus putting oil in your turbo inlet like you have pictured.

In my case, and possibly yours, when you do not run a catch can, the small factory PCV system is over run. By disconnecting it, you still have too much crank case pressure, you are just not putting the oily air back into your system.

You will not get burning oil while on the throttle because the PCV valve is closed. It opens with vacuum. Imagine this. You have a very high positive pressure in your oil pan. and you have a very high pressure in your combustion chamber while on the throttle. Because ya know, there are explosions happening in there. So for the sake of argument we will say the pressures are equal. Which means everything is staying where it is at. Well when you lift the throttle, there are no more explosions and now there is a negative pressure, or vacuum. Well you still have a positive pressure in the oil pan because its backed up by your stock PCV system and has no where to go. And now there is vacuum in the combustion chamber and the only thing separating the two are your piston rings. So once the pressure in the oil pan is high enough, the vacuum in the combustion chamber is going to suck that oil and air up into the cylinder past the piston rings. Thus burning oil.

Also to add you need to be sure the smoke is blue. If its white then that is more than likely a head gasket issue. And that could be your vacuum in your cylinder when you close the throttle sucking in coolant past the head gasket if I had to guess. But if disconnecting the PCV fixed the issue its probably blue smoke and you need to do what has been stated with the catch can. A quality sealed can is going to help a lot. As well as adding some AN fittings to the valve cover.
 
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