Another swirl flap prob?

[Devonsteve]

Hi guys, I have a 2011 xc90 D5. Recently lost power and a hissing sound, affected when accelerating or boost. Needed a service anyway so used local dealer. Serviced it then charged another £54 to diagnose. Gave me codes pointing to air flow and said the swirl flaps need updating to the tune of £450. I'm ex mechanic but a bit rusty. I looked at the stepper motor and arm, and the arm is disconnected? The flap linkage is nice and free. I put the arm back on and it seemed to stay put. Got to a hill last night and no power, wouldn't go over 20mph. Checked stepper motor today and it does move but the movement is slightly twitchy. Would I be on the right track replacing arm and motor? I know about the ball wear thing but can look into that after. Am I missing something? The dealer also didn't say anything about the arm off or checking motor? Any input welcome.

[SwissXC90]

Swirl flaps are used for idle and low engine speed emission control. Once the engine is above about 1500 RPM, the swirl flaps play no role. So you can disconnect them and open the flaps, and go for a drive and try it out.

If you are suffering a serious loss of engine power, with a hissing sound, look also for a charge air leak in the charged air pipes and intercooler.

But more on the swirl flaps:
Swirl throttle
The swirl throttle consists of a DC motor (12 V), position sensor (Hall sensor) and throttle link arms. The swirl duct generates a swirl motion in the intake air for more efficient combustion at low engine speed.

The engine has a stepless, variable swirl system located on the cylinder head. The swirl system rotates the air in the combustion chamber for effective combustion. Variable swirl enables fine adjustment of combustion, for effective combustion and low emissions. At idling speed, the damper is closed and air rotation (swirl) is high to facilitate combustion of the soot particles.

The higher the engine speed (rpm) and torque, the more the throttle opens and the swirl is reduced, to improve power / performance.

Disconect the arm and see if the swirl flaps move freely
Make sure there is no oil leakage around where the flap arm comes out of the inlet manifold. If there is, the seal is bad.

Unfortunately, all diesels (all makes and models) suffer from coked up inlet manifolds with time, affecting all swirl flap mechanisms. It can happen that the swirl flaps are so coked up that they do not move, move slowly, or don't open or close properly.
Repair can be as simple as cleaning, but may need swirl flap replacement, and always requires the inlet manifold to come of the engine - with all the hassle of disconnecting injectors etc.
Messy and takes a bit of time, this is likely why you have the 450 GBP quote.

As for the electrics, the ECM exercises the swirl flap throttle motor (the electric motor) every 5 or so engine cycles. So disconnect the arm, and get an assistant to turn engine on and off about 5 to 10 times. On one of the cycles the swirl flap motor will exercise the arm through the full movement range. An easy check to make sure the electrics and motor are good.

[Devonsteve]

Thanks for the info mate, just checking my thinking. With the link disconnected flap arm is really free. There is a lot of gunk around it which would be the seal you mention.

Because of the hiss, I was surprised they said swirl flaps to be honest. Still may be the intercooler, I'll check. I'll also run the flap motor through it's diagnostics, because the motor does seem twitchy throughout movement. I'll wire the flaps open and try it. If the massive power loss is still there it would point more to the intercooler. Prob need cooler, flap motor and linkage changed I bet lol. I'll update and thanks again.

[Devonsteve]

Ok, the stepper motor seems to be working. When I rev the engine it activates bit doesn't stay activated. It works on initial rev but closes again even if the revs are held. Is it supposed to hold position wherever the rev range is, or does it just activate for initial acceleration?

With the linkage disconnected, I pulled UP the little arm and wired it in position. No change in power. Barely crawled up my hill.

Checked all I could see around the intercooler and pipes but everything is in place and clean. Other than get all the front off and the the intercooler rad off, any other way of checking if that's the problem?

Going to change the arm as that is worn.

Cheers guys👍

[SwissXC90]

Stop focusing on the Swirl Flaps, I do not believe they are the cause of a massive loss of power

At this stage I can only recommend connecting VIDA, and seeing what the engine ECM is reporting

[Devonsteve]

Originally Posted by SwissXC90

Stop focusing on the Swirl Flaps, I do not believe they are the cause of a massive loss of power

At this stage I can only recommend connecting VIDA, and seeing what the engine ECM is reporting

Thank you.

[Devonsteve]

Originally Posted by SwissXC90

Stop focusing on the Swirl Flaps, I do not believe they are the cause of a massive loss of power

At this stage I can only recommend connecting VIDA, and seeing what the engine ECM is reporting

Thank you.

[Devonsteve]

As the swirl flaps have nothing to do with the power loss I'm experiencing, it does mean I can't rely on my local dealer as he said the swirl flap system needs replacing. £450. It seems nowadays diagnosing a problem for £54 means just plugging in and printing off the codes which is no good to me. I'll look into getting vida myself but will post seperatly.👍

[xco]

Just PM'D you Steve

[Odysseus]

I’m no mechanic but this sounds very similar to the problem I had in my 2012 XC90 a few months back.

https://www.volvoforums.org.uk/showp...4&postcount=65

The problem was a crack in the charged air pipe, and had exactly the hissing and power loss you describe.

The pipe part itself was £210 plus VAT, plus costs for fitting. I ended up needing additional stuff done with DPF sensors so my total bill was just over £700 from a Volvo indy, but would have been circa £400 for just the pipe diagnosis and replacement.