BMW Swirl Flap Failure
BMW Swirl Flaps Problem
Worried by the stories about diesel swirl flaps? Here's what you need to know.
Info on BMW diesel engines.
Swirl flaps.
Swirl flaps are designed to create swirl or tumble of the air to aid better combustion under light load where soot levels tend to be dominant because of the lack of air, they are also there to help with driveability in low load conditions, they are controlled by a vacuum or solenoid actuator and are closed during light-load operations such as when idling at traffic lights, changing gear and deceleration to maximise combustion efficiency, fuel economy and emissions performance. The flaps are fully open during higher load conditions to maximise volumetric efficiency and power output.(more info below)
Swirl flap control DDE 4.0
The controllable swirl flaps are located in the intake pipe and are closed or opened depending on the operating status. The flaps are closed at engine speeds below approx 2000 rpm and injection volume below 30 mm^3.
Function.
The pressure converter connects the vacuum unit with the vacuum supply by means of hoses. When activated by the DDE control unit, the changeover valve switches vacuum to the vacuum unit thus operating the control rod and closing the swirl flaps. The control rod is up against the rear stop when the swirl flaps are open.
Troubleshooting.
Fault code 1A22 "Swirl flaps" is stored if a defect occurs in the activation of the pressure converter.
Effects of faults.
Swirl flaps stick in open position: Deterioration in exhaust gas characteristics in lower speed ranges otherwise no effect.
Swirl flaps stick in closed position: Power loss of approx. 10 % at higher engine speeds.
Electrical swirl flaps DDE5.0/DDE6.3
The adjustable swirl flaps are located in the tangential channels of the intake system and are opened and closed according to the operating status of the engine. The swirl flaps are closed under the following conditions:
at low engine speeds and low injection volumes (map-controlled)
The swirl flaps generally open when
the coolant temperature < 14 ºC OR
the amount of fuel > 24 mg OR
engine speed > 2250 rpm OR
the intake temperature < -5 ºC.
Function.
In the case of the M57 TU with exhaust emission stage EURO 4 and the M67 TU, an electric motor activates the control rod to close the swirl flaps, the swirl flaps are sealed when closed in the tangential ducts with rubber gaskets. The control rod is up against the rear stop when the swirl flaps are open.
Effects of faults.
If the swirl flaps stick in open position: Deterioration in exhaust gas characteristics in lower speed ranges otherwise no effect.
If the swirl flaps stick in closed position: Loss in power output of approx. 10 % at higher engine speeds, danger of engine overheating.
With no Vacuum applied the flaps are open, so if the vacuum system / solenoid fails the flaps are open.
Swirl flap failure.
Swirl flap failure being reported on BMW diesel engines including later models, less than 10000 miles reported.
When the swirl flaps fail they usually break through the metal shaft where the screw/rivet goes through, these then drops into the inlet port and either jam the valve open and the piston smashes against the valve or they drop into the engine, this can cause the piston bore to become badly scored and the piston top can be damaged from the parts embedding themselves in the piston, it's also known that parts can go back up through the open valve and into another cylinder.
BMW have made the spindle stronger by using 4.5mm rod instead of 4mm rod, as found on around April 2004 manifolds.
What is the solution?
BMW introduced an updated manifold in 2004 to address this problem, the spindle of the valve is thicker and stronger, this design is also prone to failure, another option is to purchase a new manifold and install it, however you will still havethe potential for the same problem to occur.
The easiest and cheapest solution is for us to instal our custom manufactured blanking plates, the blanks will fit in place of the current mechanism, there is no modification required!
The car will function the same without the flaps, the flaps are there for emissions purposes, however the car will remain within guidelines and you will not notice a performance change!
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