Hey, so I replaced my PCV system last december, around 5K miles ago with a unit from ipd.

Lately, under slight acceleration, there is a slight stumble, under full throttle, slight stumble, very minute that I feel through my feet.

Now, I unhooked the two hoses from the PTC nipple, covered the PTC nipple and other hose with tape. There is no hesitation under light throttle at all, but a very minute stumble under full, can barely even notice it.

After a long drive this evening all over town and highway, triple digit speeds and full throttle merging, the car did a good job! So when I got home I left it running, popped the hood, pulled the dipstick and it's smoking, not billowing, but smoking. Also smoke from the PTC hoses which I expected.

I don't mind the smoke from the hoses, but from the dipstick? The car feels better with them disconnected so i'm not feeling to put them back on and get stumbling without dipstick smoke...

Would any of you think twice about this scenario? I don't think the rear main seal would be affected, right?

Any replies would be appreciated.

Am uploading a vid of said smoke now....

http://youtu.be/KKs7JzWMBJ0

 

Well, if either of those hoses are disconnected you get a cel right? Also, they didn't design those hoses to be left off so I wouldn't leave them off. Other than all that when was the last time your wires were replaced?

 

VMAX: There are threads here that explain the function of the PCV and PTC. They are vital to your engine's health. Unless of course, you love experimenting and have nothing else to do with your time and money.

You said "Unit" from IPD. What unit is that?

 

RSPI: No check engine light. Bought new Bougicord wires right before I got the PCV kit from IPD last december.

Henry10: Why does the car feel worse with the hoses connected? Shouldn't it feel fine with them on? I got the PCV kit (unit I call it) from IPD. Really, how is the PCV vital to my engine's health when it's there for environmental reasons only. I actually think volvo said "Hey, let's route excess crankcase pressure to the turbo to pass smog, performance may suffer, but oh well."

Car hesitated off and on about 1 month ago so I got new Volvo OEM plugs, gapped em .28, and a bosch fuel filter, car slightly hesitated last week so I pulled off the PCV hoses and the car feels lively at all rpms.

I went to the junkyard today and pulled off two more hoses from an 850 Turbo to use as extensions to carry the smoke under the car. All the PCV design does is blow excess crankcase smoke into the turbo from the intake pipe from what I see. As long as the smoke escapes, the seals will be fine, doesn't matter where it escapes to from a practical, not environmental, standpoint.





Sticks out right beside the subframe...

 

PCV: Positive Crankcase Ventilation
PCT Valve: Positive Coefficient Temperature Valve.

PCT is the heartbeat of the PCV system. However PTC is only one component in it.

The real issue is not environmental. These engines are designed with a certain balance of pressure/vacuum/intake. The dumping of the crankcase vapors back into the intake happens at certain conditions. At some condition, there is no flow, in others, the Valve opens partially, in some others open more (VARIABLE). It is the PTC Valve that regulates this flow of gases/vapors that keeps the engine in pressure/vacuum balance. People bring up leaking of seals as a result. That is the least of the worries. Engine wear, even crankshaft wobble or even cracks are possible -- read up on it.

This PTC Valve has 3 inputs -- crankcase pressure, fresh air pressure, and throttle/intake vacuum values. Based on these 3 values it regulates (VARIABLY) dumping of the Crankcase gases, which relieves pressure in the crankcase.

This PCV system is not used only on 850s but throughout Volvos.

What is the problem with people? Clean / replace those cans and stupid 3rd-Grader plastic lines system, including cleaning of the PTC. If you did not clean the PTC, of course you will have problems...

 

When i just bought the car it felt inconsistent, like something was holding it back... Smoke blew out the dipstick and I could feel the motor not producing due to crankcase pressure(I could see how crankshaft wobble/cracking would happen here). Well I cleaned the PTC nipple thoroughly, it felt a little better, still crappy tho, then changed the breather box and hoses with a new set from ipd, car felt great. Now completed all of stage zero(plugs,wires,cap/rotor,fuel filter/k&n drop-in). Why, Henry, why is my car still hesitating sporadically with the hoses on?

Am I missing another component that pertains to engine behavior/tune up?

With the hoses off, no CEL, 90% less hesitation. The crankcase pressure escapes and does not build up.
Engine wear or crankshaft wobble/cracks would be a result of too much pressure, no? That happens when you don't clean the ptc nipple or change the pcv box/hoses.

In my case, all that is cleaned/replaced, full tune up still a slight hesitation occurs but as soon as I disconnect the hoses letting pressure relieve the car wakes up and is light on its feet.

Put it like this, time will tell, i'll scoot around with a happy feeling motor until what you say may or may not happen. Either way, i'll revert to this thread and let you know the results.

 

LOL. Go for it....

 

Little update: T5's still happy.

http://youtu.be/3h-f09KDFlM

My fingers are glued crossed. (whatever that means)

 

Volvo gods will punish you soon enough

 

The Gods will see that i've treated their offspring better than my own child...they're content.

 

It just occurred to me why the dipstick tube smokes, it's attached to the crankcase...smoke escapes through all holes on the crankcase, from the breather box(two holes) and the dipstick tube. Mapping out the mechanics in my head and seeing how the engine reacts positively shows that pressure will never build up, but you will fail smog tests, and track inspections.. but oh well, my track does not check and this is Florida, home of no emissions testing!

 

Well I guess the hoses should be connected.

Long story short, under full throttle in 1st gear, around 5K rpms it loses power completely and hisses like a snake, but is ok in 2nd,3rd,and 4th.

So, I reconnect the hoses and it still acted up in 1st initially, but is fine in 2nd,3rd,and 4th. When connected, it definitely feels like it's being held back at times, not as light on its feet when the hoses were disconnected so I guess it's when the crankcase gases and fluids build up and is dumped to the turbo is when it hesitates. Right now with hoses on, hesitation is inconsistent which I do not like! Sometimes it blasts down the street, other times it bogs slightly.

I need to find a way to dump the gases through the exhaust but still keep the ptc sensor content...dumb swedish engineers.........

 

Something is up. I don't think it is the PCV. I think the best approach is to do some diagnostics, take some readings first.

I would start with this How to Use and Interpret a Vacuum Gauge. Which scenario is you? If you haven't yet, I would invest $ 10 in replacing all vacuum hoses.

While you are at it, take some fuel pressure readings, idle, and WOT.

I would also scan for DTCs.

If you get nothing, I would go into probing various sensors. To be honest, the symptoms you are describing may come from fuel pressure problems, vacuum leaks, unmetered air (MAF?), and a million other causes.

Take a mallet and hit your cat (I mean catalytic converter) -- does it rattle?

 

Just scanned the car for codes yesterday, nothing at all.

Silicone vacuum lines installed for sometime now. I'll get a vacuum gauge and fiddle around.

What I don't understand is why the car feels so damn good with the hoses off...but feels mediocre with them on.

No rattle from cat at all, hit it decently a few times on both sides. sounds sturdy.

 

You say car doesn't work right either way, so somethn's wrong. When can hypothesize all we want, but you need to find what's wrong with it first.

Do you have EGR? Air Pump?

 

I may never know if my cars have this problem because I rarely rev above 2500 rpms. Better gas mileage.

 

No EGR according to the VIN decoder i've printed out for 1997 MY 850s. My vin # is YV1LS572XV1368421.

After the 57, this is what the decoder syas verbatim:
"2 = w/o EGR w/o air pump, w/ OBDII, w/elec. control evap, Motronic 4.3 (57,58)"

 

You NEED to get in boost man, you're missing out..lol

 

No EGR. No Air Pump. Good so you can't delete them. Now go buy a $ 15 Vacuum Gauge and take some readings..

 

i'll report my findings to you this time tomorrow...thanks for your help dood.