Inside the intake manifold are small butterfly flaps on modern diesel and petrol engines, they are designed to regulate the fuel to air ratio, improve emissions and help to create better torque at low engine speeds. During light engine loads the flaps close, causing the air to swirl into the combustion chamber, the swirling affect aids the combustion process and helps to improve emissions and generate more torque. After around 2000 rpm the flaps are generally operated to a fully open position and have very little effect on engine performance and emissions.
What are the problems?
Major Mechanical Failure:
Early BMW’s were fitted with metal flaps which were very prone for failure, the metal locating screws holding the flaps to the spindles would become loose over time and enter the combustion chamber causing catastrophic engine damage leading to in most cases a costly engine replacement.
Over time the seals surrounding the flap spindles deteriorate and cause pressurized air from the inlet manifold to leak to atmosphere. This causes a loss in boost pressure which causes the engine to run a rich mixture and can damage other components such as DPF, ERG, etc.
Carbon build up:
Carbon deposits from the EGR system along with oil vapours from the breather system cause carbon to build up on the butterfly flaps, this can reduce the intake manifold size and can hinder performance. We have seen many manifolds heavily restricted by carbon deposits around the inlet flaps causing almost a complete loss of performance and fuel economy.
Modern manifold systems today incorporate an electronically controlled actuator which opens and closes the flaps. These actuators can fail, along with the position sensors, in many cases this can result in the flaps staying in the closed position which significantly hinders performance, along with illumination of the engine management light and in some cases limp mode.
How do we remove them?
The process for removing the flaps is design dependent, in some cases the manifold is removed and the flaps physically removed, in other cases where the mechanical status of the flaps are in good condition and the fault is due to an electronic actuator failure the actuator function can be disabled and the flaps left in place.
What are the negatives?
We believe very little, the reduction in performance and emissions at low engine speeds is almost unnoticeable and would only be relevant if no carbon build up had occurred, due to the fact that carbon build up begins as soon as the vehicle leaves the factory, the removal of the flaps is likely to result in increased performance and efficiency.
What does it cost?
The cost of removal depends on the design of the manifold and flaps, contact us with your vehicle registration and we will be more than happy to offer a competitive quotation.