White smoke on deceleration

[Bdevo3]

I have a 95 lancer evo 3. When I drive normally or even spirited I have no smoke issues but when I really push it hard up through the gears and ease off on the accelerator for a moment and get back on it hard I get a puff of white smoke. The turbo has been rebuilt ,head gasket replaced along with stem seals and a complete gasket kit. Intercooler and pipes have been cleaned, leak down test registered perfect. Dump valve replaced. I just can't figure out what the cause is. Any ideas

[Bdevo3]

It's very unusual. I don't have any signs of smoke at normal driving or the the odd push up through the gears but it's like if I hold high boost for a period of time release the throttle coming into a corner and back on it then its getting oil into the exhaust for a split second and then it clears if that makes any sense. Too much boost possible?

[Bdevo3]

Standard 4g63t and td05 16g turbo when the turbo was rebuilt it ran 1.1bar of boost on the bench tested. Hks mushroom filter, sard fuel pressure regulator set to 3 bar, magnecor leads, sard bov, j performance manifold and elbow, hks 3 inch exhaust with no cat. Normal/spirited driving it holds boost at 1.1.very hard driving it will sometimes spike and hit a fuel cut. Have I got a boost creep issue? I have replaced all vacuum hoses and boost solenoid.

[Bdevo3]

That sounds like what I'm experiencing as it clears very quickly and doesn't continue when I keep driving hard. I've ordered a boost controller to hopefully cure the boost spike, I've read a straight through exhaust can cause boost spike on a standard ecu. As said it only happens with high boost pressure so hopefully reducing it to 1bar will stop it . I think 1bar will be enough to run on standard internals

[Bdevo3]

Mr2Mike said:

227bhp said:

He said the valve stem oil seals have been replaced.

Were the guides checked checked for wear and replaced if required? New seals on worn guides don't do much.

I gave the head to a highly regarded engine builder and told him to put whatever it needed in to. The same with the turbo it got a complete rebuild. After speaking to the man who did the head he recommended adding a non return valve and oil catch can to the pcv system as it is a weak point on the 3. Manual boost controller arrived today so hopefully stock boost and his recommendations will cure it over the weekend

[Bdevo3]

I fitted an oil catch can between the pcv valve and inlet manifold and installed a non return valve on the inlet side which has cured the smoke issue, well so far so good anyway. Next i fitted a manual boost controller, I ran a pipe from the inlet manifold and teed in the boost gauge, then further along the dump valve, then the controller to the actuator. With the softest spring in it and at its lowest setting I'm still getting 1.5 bar. My actuator is adjustable would increasing the length reduce the boost down to a safe 1.1 or 1.0 or am I going wrong somewhere

[Bdevo3]

It's flowing the same direction as the pcv valve

[Bdevo3]

GreenV8S said:

I take that to mean it allows flow from the separator to the manifold, and blocks the return flow. How does that help?

the standard pcv valve are a weak point and even from new have a tenancy to stick open with aftermarket exhaust and induction and allow oil into the intake. Higher boost makes it worse and causes the dip stick to pop up and all sorts of nastiness. So the Internet tell me. Common issue on early evos apparently

[Bdevo3]

The pcv valve itself is a check valve which opens under vacuum to release crank case pressure when it closes the crank case draws clean air from the intake pipe. When it sticks open when the car is in boost the oil is drawn through it into the intake to be burnt causing the smoke. Putting in the check valve is essentially putting in a second pcv valve so if one sticks open in theory the second should stop any oil getting through

[Bdevo3]

GreenV8S said:

Bdevo3 said:

The pcv valve itself is a check valve which opens under vacuum to release crank case pressure when it closes the crank case draws clean air from the intake pipe.

Are you sure about that? I've never seen a PCV system that works like that.

My apologies I had a few pints in me last night it draws air from the air intake pipe while the pcv is open. I've used these diagrams from dsm tuners