P2097...driving me bonkers... yes, AGAIN (P2 - 2002 V70 2.4T) Topic is solved

[Jonboy74]

Not unlikely you'll be able to find it by visual inspection.

LOL, I must be blind....

Ok, so where can I get a smoke machine? I checked the Autozone loaner tool program and doesn't look like they have one....I'd rather not buy one, unless I can get one for cheap...

Thanks,

Jonboy

[vtl]

Ok, so where can I get a smoke machine? I checked the Autozone loaner tool program and doesn't look like they have one....I'd rather not buy one, unless I can get one for cheap...

Build one? Or ask in shops around your area if they can diagnose the leak for you.

I have this one: https://www.amazon.com/gp/product/B07JVT1NG2 It is not cheap for what it really is, but it worked.

Or you can get a can of starting fluid (with ethers) and spray it in burst along the intake with the engine running. When you hear the RPM deviating - you just sprayed in proximity of the hole.

[abscate]

I thought you can command throttle position in Vida?

[Jonboy74]

Build one? Or ask in shops around your area if they can diagnose the leak for you.

I thought about building one, and it would be fun, but right now my time is worth too much to deal with getting the parts and tinkering around......but by the same token, if I'm going to pay a shop to diagnose it, I might as well buy a cheap one...

I have this one: https://www.amazon.com/gp/product/B07JVT1NG2 It is not cheap for what it really is, but it worked.

I ended up ordering the economy version direct for $79 including shipping: Autoline Pro Economy Smoke Machine

Or you can get a can of starting fluid (with ethers) and spray it in burst along the intake with the engine running. When you hear the RPM deviating - you just sprayed in proximity of the hole.

I did try that the other day, but I didn't have any success.

I'll post back once I get it and have an update. For now, the car is more or less behaving (at least enough for me to deal with....) crossing my fingers that it doesn't get worse between now and when I get the smoke machine.

Goodnight Elizabeth!

Jonboy

[Jonboy74]

Bingo! (maybe? I'm cautiously optimistic at this point... )

I got the smoke machine yesterday evening and hooked it up today. Smoke POURED out of the intake pipe where the PTC grommet meets the air intake. I didn't see any coming from anywhere else, but considering how much was coming out, it's possible there is a smaller leak somewhere else...

When I took everything apart a year ago, that grommet was pretty hard - I should have replaced it then, but I was being stubborn, AND I didn't realize that small of a leak would cause me this much grief!

Now the question is....do I just replace the grommet for ~$9.00, or do I replace the entire Air Intake Hose Assembly that includes the PTC Valve (~$50-$60) and grommet pre-assembled for $125.00....?

For anyone else who might be following this thread, here is the part I'm talking about:

Volvo Air Intake Pipe Grommet - Genuine Volvo 3507985

This grommet fits between the intake pipe and the PTC Valve (PTC = Positive Temperature Coefficient)

Here is the Air Intake Hose Assembly


And in case you were wondering, here is some info on the PTC valve:

WHAT MAKES A PTC VALVE WORK?

And.....I MAY have answered my own question as to whether to replace the entire assembly or not. Have a look at this post - I'd be interested for anyone who ahs feedback on what you would do if this were your car:

Volvo AWD Forum - Why it is important to keep the PTC nipple clean

Thanks!

Jonboy

[vtl]

I have replaced the whole pipe. It is known to develop cracks over years, plus I needed a new PTC valve: the original was filed wider to compensate for blow-by gases and extra flow resistance of external oil catcher can. After the engine has been rebuilt, the can was thrown out, yet the fuel trim was a bit awkward for a "new" engine. New PTC solved that.

Grommet replacement is royal PIA. I did that for old pipe once and not looking doing it even one more time.

[Jonboy74]

I have replaced the whole pipe. It is known to develop cracks over years, plus I needed a new PTC valve: the original was filed wider to compensate for blow-by gases and extra flow resistance of external oil catcher can. After the engine has been rebuilt, the can was thrown out, yet the fuel trim was a bit awkward for a "new" engine. New PTC solved that.

Yeah, the plastic being old and hard, and exposed to heat over time - that makes sense.

...but that leads to my next question...

How on earth did you determine that the PTC valve was the issue in that situation?

Grommet replacement is royal PIA. I did that for old pipe once and not looking doing it even one more time.

I do remember how much of a pain it was pulling the PTC and grommet out and putting it back in. I don't know why I disassembled it - maybe my unfamiliarity with it, or I had difficulty with the hoses, I really don't remember....but getting it back together was FUN!

Thanks,

Jonboy

[vtl]

How on earth did you determine that the PTC valve was the issue in that situation?

Ah...

Years ago I've built myself an extended CAN-bus monitor: https://github.com/vtl/volvo-ddd/ It reads/displays a lot of sensors, so I can keep an eye on things like fuel trims while driving. No need for DiCE/VIDA.



Before the engine died, it has got all the new sensors, so I knew they are not "tired".

After the rebuild the fuel trim went slightly off. The only thing that changed was the new piston rings and re-honed bores, so the amount of blow-by gases went down, the crankcase got more vacuum, it started to pull more air from the long PCV pipe, which is not as restricted as it was before, because I filed that PTC hole to its max. Filed from this:



To this:



In order to verify my hypothesis, I partially clamped the oil catch can hose:



And the fuel trim went to norm quickly:



So I knew this is a parasitic vacuum drain through PTC. I got the whole new pipe, installed it, threw out the catch can and all is good now.

[darylrobert]

if you cant find anything check the vacuum one -way check valves. i found 2 out of 3 of mine were gone.

[Jonboy74]

if you cant find anything check the vacuum one -way check valves. i found 2 out of 3 of mine were gone.

2 out of 3? Where is the third? I replaced the evap hose assembly a couple weeks back and it included two check valves....

Volvo Evap Hose - Genuine Volvo 30757307

Volvo Evap Hose - Genuine Volvo 30757307.jpg (14.76 KiB) Viewed 676 times

Thanks!

Jonboy