White smoke on deceleration
Discussion
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
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?
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.
jontysafe said:
Fail to see why enrichment would cause steam?
Rule of thumb would see enrichment puff dark grey/black smoke surely?
Burn petrol you get water vapour ie steam which is frequently confused with white smoke.Rule of thumb would see enrichment puff dark grey/black smoke surely?
In the circumstances the OP is describing immediately beforehand the engine is getting no/next to no fuel, then when he goes "back on it" the petrol then entering the combustion chamber burns & gives a "puff" of water vapour (similar to initial start up or when cold) out of the exhaust.
OP, obviously this is reliant on what you originally describe as a puff of whit smoke, or is it more than that?
Possibly worth a pure white rag loosely hung parachute style over the exhaust & replicating the symptom to see if it smells of anything.
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
Don't know how obvious the smoke colour is to you when you're driving, but if you aren't familiar with the variations in exhaust smoke colour then I wouldn't put 100% confidence on that being white smoke rather than blue, grey, black etc. You would expect to get a rich spike when you jump on the power, especially when you're in the power band with plenty of boost, and if it's that then there is no problem.
If you have a recirculating crank case ventilation system with a faulty PCV check valve then it's possible the PCV system is pulling a lump of oil vapour in when you close the throttle.
If you have a recirculating crank case ventilation system with a faulty PCV check valve then it's possible the PCV system is pulling a lump of oil vapour in when you close the throttle.
jontysafe said:
Fail to see why enrichment would cause steam?
Rule of thumb would see enrichment puff dark grey/black smoke surely?
Rule of thumb would see enrichment puff dark grey/black smoke surely?
you won't get puffs of visible water vapour when the engine/exhaust is up to temperature, unless there is something very wrong.A puffs of smoke when re-applying the throttle after coming of it are usually caused by worn valve stem seals. The inlet vacuum created when you back off pulls oil down the guides and then it gets burnt when you get back on the throttle.
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 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
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 apparentlyGassing Station | Engines & Drivetrain | Top of Page | What's New | My Stuff