2008 XC90 3.2L with codes P0171 and P0174 - Help

Turbo_Boss · Post by **Turbo_Boss** » 20 Jul 2015, 22:29

Hey guys,

I have a 2008 XC90 3.2 AWD with 75,000 KMS that I got recently.

Checking with OBD FUSION, I got the codes:

P0171 and P0174 System Too Lean

P0507 Idle Air Control RPM Higher than expected.

The car feels and drives normal but I want to fix these before it gets worse.

Searching on the web for these codes P0171 and P0174 its look like maybe the problem is the PCV but I don’t find any info, pics or DIY fix for this issue on a 3.2L engine

Have any of you with 3.2L engine has experienced these same codes?

I going to check if I have a vacuum hose leak but can you advise were I need specially to look

Thank you for your time and help

Isaac

Post by **jimmy57** » 20 Jul 2015, 23:40

There aren't any vacuum hoses on that engine other then the one hose for the charcoal canister purge valve.
The black housing on top of cylinder head is the crankcase vapor oil separator and it has a regulator valve integrated onto it. The valve is the 50 mm round thing on the housing. If the diaphrag om that ruptured it could cause suction that would draw air in anywhere it could like oil dipstick o ring. If that valve is faulty then pulling out dipstick with engine running and then putting your finger over the dipstick tube would allow you to feel for vacuum. There should be very little. A noticeable suction there would mean a bad regulator valve.
The intake seals to the head with green rubber sleeves and not a regular gasket. Loose bolts could allow a leak.
There are two electric damper motors that insert into intake manifold to control manifold and it could be possible for one of the motors to have a bad seal. The throttle seal to the manifold using a sleeve seal and that is another place it might leak.

Turbo_Boss · Post by **Turbo_Boss** » 21 Jul 2015, 00:03

jimmy57 wrote:The black housing on top of cylinder head is the crankcase vapor oil separator and it has a regulator valve integrated onto it. The valve is the 50 mm round thing on the housing. If the diaphrag om that ruptured it could cause suction that would draw air in anywhere.

Hey Jimmy57, Thank you for your help.

If the diaphrag is ruptured, do I will fill suction or a vacum hissing noise on that part?

jimmy57 wrote: it could like oil dipstick o ring. If that valve is faulty then pulling out dipstick with engine running and then putting your finger over the dipstick tube would allow you to feel for vacuum. There should be very little. A noticeable suction there would mean a bad regulator valve.

I will do this test and let you know.

jimmy57 wrote:The intake seals to the head with green rubber sleeves and not a regular gasket. Loose bolts could allow a leak.There are two electric damper motors that insert into intake manifold to control manifold and it could be possible for one of the motors to have a bad seal. The throttle seal to the manifold using a sleeve seal and that is another place it might leak.

What is the best way to test all these seals you are mention?

Thank you for your time and help.

Isaac

Turbo_Boss · Post by **Turbo_Boss** » 24 Jul 2015, 23:54

Hello jimmy57,

So today I was checking the black housing on top of cylinder head and the first thing I notice is that is all covered in oil.

The hissing noise is coming from the engine oil cap. I removed the oil cap and put my hand over the hole and there is a "noticeable" suction.

I am going to order:

PCV OIL TRAP – VALVE COVER Part No. 31319642
VALVE COVER GASKET Part No. 30731243

Can you guys, let me know what’s the correct torque setting for the torx screws for the PCV OIL TRAP VALVE COVER?

Thx for your time and help

Isaac

Turbo_Boss · Post by **Turbo_Boss** » 25 Jul 2015, 18:04

Hey Guys,

So today I have more time to check the valve cover Oil Trap and in the name of the science, research and investigation

I decide to remove the plastic cap on top of the diaphragm housing.

I know other brands like VW and BMW sell the membrane/diaphragm alone so I was expecting to see if I can replace it and save some $$$

I went to a place where they sell OEM and aftermarket parts for BMW. They were very similar but none of them fit or was the same.

On the Volvo membrane/diaphragm there is a part No. CF W 3A MB66-24

Doing a search on the net I don’t find anything under that part No. or something similar.

Anybody knows where can I get this part? If not, I will have to buy the complete valve cover oil trap

THX,

Isaac

Turbo_Boss · Post by **Turbo_Boss** » 16 Aug 2015, 22:03

Hey Guys.

So yesterday, I change the PCV OIL TRAP – VALVE COVER Part No. 31319642 on my 3.2L and cleared/reset the P0171 and P0174 System Too Lean codes and now the engine is smooth and not misfires.

So today I was driving and my check engine light come on and these are the codes I get:
P0172 and P0175 System too Rich.

Any advice what to check? Or what other test to make with the OBD Scanner?

THX,

Isaac

Here is the screen shot of the OBD Codes and also the Term Fuel % on idle on Bank 1 & 2

Saabfisticated · Post by **Saabfisticated** » 05 Nov 2015, 15:20

This is on a 2007 XC90 3.2 L6, AWD.

Did you guys ever find the part to replace just the pressure valve? I have oil leaking as well but it is all around the vavle cover. I've bought the valve cover gasket that fits it and will install in next few wks. Originally I thought it was just brake vacuum pump and I rebuilt it with the kit, but I still noticed oil leaking last night, it's noticable behind the motor in front of firewall. The fresh oil is getting on the plastic ribbed electrical wiring cover which is why I figured it was the vacuum pump leaking and getting blown behind there. But there is also loads of old oil all over the top of the motor (SEE PIC) . and it seems to be coming out around this intake. This and one other thread is all I could find on the subject. I know its old but I just thought I'd add to it. Thx in advance!!

Turbo_Boss · Post by **Turbo_Boss** » 05 Nov 2015, 16:58

Hey Saabfisticated.

I tried to just get the pressure valve diaphragm but nobody sell it alone.

Assuming your diaphragm is damage, I am pretty sure you have the malfuntion indicator light on your instrument cluster letting you know ther is a problemo.

Also, if this part is damage you will have more fuel consumption

Is this is your case, you will need to get the complete PCV OIL TRAP – VALVE COVER Part No. 31319642 http://www.tascaparts.com/oe-volvo/31319642

This part already come with the gasket so I recomend you to send back the gasket you bought and ask for a refund and then order the TASCA part.

I bought it on http://www.tascaparts.com/ and the part was around $150.00 not including shipping & Handling. They have the best price.

Good luck,

Isaac