Swirl flaps - are they worth it?

[TheMatador]

Anyone got any thoughts on the value of the swirl flaps in the V6 and V8 tdi engines?

Official documentation states "They enable the airflow to be adjusted to suit engine speed and load. Not only additional power and torque result, but also lower fuel consumption and emissions."

They seem very problematic though and expensive to fix (over £2000 to replace both sides on the V6). There's a lot on the BMW forums about completely removing them on the 2.0d and 3.0d engines with, arguably, little or no effect on performance. - see attached technical docs for how they work.

They are basically on-off valves on one of the two inlet runners on each cylinder. Possible scenarios might be:

1. Mechanism wears or gets a bit impaired e.g. linkage is worn giving "lower limit" error - valves still work though - no noticeable effect
2. Motor is faulty - valves don't operate - loss of power above 1250 rpm because spiral runner is blocked
3. Valves break off and knacker the cylinders, EGR valve and turbo

Questions in my mind are:
1. Why does problem 1 warrant the engine management light coming on?
2. Are they worth the money? Any efficiency savings are wiped out by a £2000 bill after 80k for six bits of plastic and two motors
2b. Ditto for problem 3 - a very big bill again!
3. Why do you have to change the whole thing at once - they're only on/off valves
4. Is there any way to put an inhibit on the lower limit error or change the tolerance to stop the light coming on?

[daveyboy467]

i've seen on a bmw forum the same complaints,

i thinks its just manufactures doing what they can for the green factor maybe.

and in the bmw forum they have a solution to remove them wich most handy diy'ers can do.

once again the bmw forum complain about the probbability of failure and possible damage it can cause if your unlucky.

[wjam]

Just spotted this thread.

Problem numbver 1 causes a MIL because the motor is disabled if it sees any discrepancy of I believe > 2% from expected position... The motor is spring loaded to keep the flaps open in the event of failure at ECU side.

See the VW thread here for a great fix! https://www.vwaudiforum.co.uk/forum/s...-Swirl-Control

A little bit of work but could be well worth it

wjam

[wjam]

Oh.. and to answer the question... NO they are not worth it.

Disconnect the motors and go for a long drive. I bet you see no difference worthy of their Audi cost.

If I can find a way to take them off without a MIL I'll do it.

wjam

[AxeMurderer]

Mine have been broken for a while now. I don't see any decrease in fuel consumption on long motorway journeys. I suspect that fuel consumption is a little worse on short journeys though. I certainly don't see £2000 worth of consequences!

[gianton]

How do you tell if they are broken?

[wjam]

The engine light comes on. (MIL) But you need to get a fault diagnosis to absolutely confirm the issue.

As a quick check you can pull of the engine cover and watch the motors after starting.

They reference back and forth then jump to closed position for idle. Blip the throttle and you'll see them shift to open then close again as revs return to idle

Bear in mind default position is open (so that the car runs if they fail)... Also left side is opposite direction to right side. Left side seems to fail most and I'd like to bet that's due to the extra heat from turbo right beside the plastic rod end bearings

cheers

wjam

[gianton]

Thanks for the heads up mate.

[wjam]

No probs... By the way.. 9.9 ltr / 100km? Are you driving in town a lot (like 80-% plus)? I'm getting about 8 to 8.5 ltr /100 mixed 60% motorway and 40 percent A road & mountains.

dropping towards 8 now after remap... which i can highly recommend (superchips)

WJAM

[gianton]

Diesel quality in Greece is the reason. I get at least 15% more mileage when I travel in Germany or other EU countries.