Diagnosing an EVAP leak on motronic 4.4

[abscate]

Im trying to imagine diagnosing these things without codes - that would suck...

Moreover, think of how much cleaner the air is now thanks to this stuff - one of the few things we can proud of passing on to the kids.

[xHeart]

Passed another emission test with flying colors today.

[deepsouth]

Anyone have a part number on the inline filter? The one on my V70 AWD acts like a check valve (can blow into it one way but not the other) but the same filter on my S70 does not and takes air both ways (leading me to believe it's bad).

[xtrattitude4u]

Check valve or filter?

The white/black piece near the intake manifold is a check valve, and should only allow air one way.

fullsize_5499.jpg (21.23 KiB) Viewed 3481 times

IPD part# 115580

The charcoal filter is mounted on the right side of the fan shroud.

Volvo-Carbon-Filter-9186744-OES.jpg (101.02 KiB) Viewed 3481 times

Swedishautoparts.com part # 9186744

[deepsouth]

I found the part (thanks xheart!). It's a check valve that's part of the evap system and apparently runs about 73 bucks or 138 bucks for the kit shown below. Anyone know of a cheap replacement?

[erikv11]

For sure I have read here about people replacing that with a generic check valve for like $15. I tried some searching, but I could not find the post. Also, I know I have an extra one, used but working, and I could send it to you pretty cheap. Send me a PM if you're interested.

I bet a junkyard would charge you maybe $5 for that check valve, pick up a few of them.

[cn90]

UPDATE...

The Bosch 0280142300, about 3 years old, is dead. This Bosch valve was "made in China".
Paid bout $40 in 2012. What a waste of money.

Happened to see a S70 at junkyard with Pierburg valve, so I investigated further and found that:
Volvo PN 9470775 is the same as Pierburg 722517040.

Pierburg 722517040 is about $35 online. Found an ebay seller that has an old stock and bought it for $22.

See the photos of the new Pierburg Valve (which is made in Germany, according to the label on the casing) vs the "made in China Bosch" valve (which failed in the OPEN position, I could blow right through the hole).

Replacement is a 5-minute job. However, one can't re-use the rubber mount designed for the round-shaped Bosch valve (with 2 Torx screws). No problem: Zip Tie came to the rescue. All is good.

I will report the long-term result on the Pierburg valve later...

[sleddriver]

I found the part (thanks xheart!). It's a check valve that's part of the evap system and apparently runs about 73 bucks or 138 bucks for the kit shown below. Anyone know of a cheap replacement?

I've recently been down this trail myself...the incredibly expensive, illusive grey Volvo check valve. My indy uses ATE 1228272 as a replacement. AutohausAZ & others carry these for about $10. I also discovered Volvo 9485451, which looks the same as the ATE part.

Another Volvo number is 1275226, which looks nearly the same as the grey one, except it's black. My local dealer didn't stock it, but quoted $19. MUCH better than the expensive "kit".

[cn90]

Two (2) weeks and 500 miles update: no EVAP codes on scanner.

So, yes the Bosch EVAP valve (made in China) failed after some 2.5-3 years.
The new Pierburg valve (made in Germany) works as expected, and hopefully this will last some 10 years+ as the original.

---
Re: EVAP codes. It took me a long time to understand it but for the records, I think this is what the design is (please see diagram posted on page 1):
- The system is air tight, only allowing air coming in when engine is running and fuel is being consumed.
- The tightness is accomplished by:
a. Tight gap cap seal.
b. All hoses intact and not cracked.
c. The Air Valve being closed all the time, except when triggered to open during starting period.
d. I am not sure but somewhere in the system there is a "vacuum sensor" (maybe on top of gas tank) that measures vacuum (probably in units of inches of Hg, but you can convert to metric etc.).

So, when you start the engine:

1. The ECU tells the Purge Valve to open let's say for 15-30 seconds (hey I may be wrong, don't know the exact amount of time it opens) to allow the fuel vapor to enter the intake manifold for combustion.

2. During this 15-30 second period, the ECU monitors the "vacuum sensor" and that is all it cares about.
And during this 15-30 sec period, the fuel system should be under vacuum similar to intake manifold vacuum (let's say > 20 inches of Hg).
If you have a broken hose, the vacuum is close to zero: the vacuum sensors registers a reading of equiv of "0" inches of Hg. The ECU will set a code consistent with broken hoses (leak in system).

3. After this 15-30 sec period, the Purge Valve is closed, The system vacuum is monitored and it should be slightly low such as 2-3 in of Hg (b/c fuel is being consumed). Now if the Purge Valve is stuck open, the vacuum is above spec, let's say 20 in Hg. The ECU knows the valve is open b/c the only way to have such high vacuum (as the I.M. vacuum) is to have the Purge Valve stuck open.

So, this is what my understanding is:
- The ECU monitors the "vacuum sensor".
- ECU monitors the time period during the engine cycles (new start vs running).
- The "vacuum sensor" can send a variety of readings from 0 vacuum to too much vacuum, allowing the ECU to interpret according to time period.

OK, this is what I understand, any EVAP gurus, please chime in...