Diagnosis of a Failing BMW DISA Valve: Symptoms, Problems, and Repairs

Symptoms, Problems, and Repairs for the Failing BMW DISA Valve. Differenzierte Sauganlage and due to the fact that German’s can’t pronounce this either, BMW simply took the very first 2 letters from each word and called this the DISA Valve.

BMW’s engineers found that the air path through the engine system has an influence on performance. In an effort to improve performance, BMW released the DISA valve in 1995. The valve is responsible for managing air as it moves through the intake, leading to enhanced performance.

Included in the E39 5-series in 1995, the DISA valve endured until the retirement of the M54 engine in 2006. Throughout its 11-year life, the valve was used in the M50, m54, and m52 engine which were mainly used in the E36/E46 3-series, E39/E60 5-series, and a number of the X3, X5, Z3, and Z4 designs.

How does the DISA Valve work?

If our short description above wasn’t enough for you, read this area.

Prior to getting in the engine, consumption air flows through the consumption manifold. The manifold is what distributes the intake air into the 6 separate cylinders of the engine. When the cylinder valve is in an “open” position, it lets air into the cylinder, and then as the valve “closes” it cuts off air from going into the cylinder. This triggers any air streaming in to bounce back off of the valve and back into the manifold. After bouncing in reverse off of the valve, it then bounces off the other end, sending the air back towards the valve.

Symptoms, Problems, and Repairs for the Failing BMW DISA Valve

What does a DISA Valve do?

The DISA valve manages the path the air moves through the intake system and into the engine. The valve utilizes a flap which closes and opens to either shorten or extend the course the air takes to get to the cylinder chamber.

At low RPM’s, the valve is closed, forcing the air to take the longer course to the cylinders. At high RPM’s, the valve opens up which produces a shorter path. Provided the path is shorter, there is less space for air. The end result is more pressurized air, which is in turn more combustible.

The ultimate goal of the DISA valve is to optimize performance and fuel effectiveness at both high and low RPM’s.

For the most effective engine performance, you want that air to recuperate towards the valve and reach it at the specific very same time the valve is opening again. You desire this bounce back procedure to take longer since the valves open more gradually at low RPM’s. And at high RPM’s you desire it to be quicker.

This is where the DISA valve enters into play. At high RPM’s it produces less space for air, which creates a quicker recuperate. When to open and close, the ECU is accountable for managing the DISA valve and telling it.

Symptoms of BMW DISA Valve Failure

  • Poor fuel economy
  • Rattling sound coming from the engine
  • Loss of power at high and mid RPM’s.
  • Lack of low-end torque.
  • SES/CEL light and codes for running lean.

The most telltale sign of a bad valve is a loud rattling noise originating from the consumption system. As the seals on the valve wear down, air can slip past the valve in open and closed positions, triggering a loud rattle. By this point, you will likewise begin to see bad performance, absence of power, and so on.

The valve is made of plastic and has a metal pin that holds it in place. If the valve or pin breaks, plastic or the metal rod can get drawn into the engine, which will totally damage your entire engine.

Why was the DISA Valve stopped?

Eventually, the DISA valve works at high and low RPM’s. But it isn’t very efficient at mid-range RPM’s.

BMW discontinued the DISA valve around 2012 in favor for a more complicated intake system which incorporated a 2nd intake “circuit”.

DISA Upkeep & Replacement Options.

The DISA valve will usually just last 70,000-100,000 miles. We extremely advise changing it or rebuilding it at this mileage to prevent any catastrophic failures.

You have 2 choices for repair and replacement:.

  • Change the full DISA unit: if you’re valve isn’t functioning however you aren’t getting any rattle, then you likely need to change the whole system.
  • Restore the unit: this involves changing the pin, seal, and flap.

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