I have a turbo car with 90,000 miles on it. Normally the engine is very quiet, no abnormal noise to my knowledge. From time to time, (that has already happened twice this month), I don’t seem to have a turbo anymore, the engine won’t rev above 2400 rpm, and can’t go faster than 70 mph.
At the stop and idle, I can roll the engine normally, but the turbo does not start.
What’s wrong? Should I visit my mechanic for a turbo maintenance?
The Whistle
Is there a variable geometry turbo on this car? If so, cleaning is probably sufficient. When a turbo is dead it makes another sound (pretty awful). If you’re hearing a whistle, perhaps the blades are lacking balance. This is a small job (probably part of your car’s turbocharger servicing), and will prevent damage to your engine.
Mass Flow Sensor
With a lot of bad luck, it might be the mass air flow meter (or mass flow sensor). When the flow meter becomes clogged it becomes difficult to rev up above 3000 rpm. Indeed, the flow meter measures the amount of air pulled in by the motor, and in turn sends the information to the engine management unit (ECU) to adjust the quantity of fuel required for explosion. Therefore, if it gives incorrect information the flow of air won’t be sufficient, thus reducing dramatically the output of your engine.
The flow meter also controls the operation of the exhaust gas recirculation valve (EGR).
Also to be noted, disconnecting the mass air flow sensor on a TDI won’t fix the problem.
The Problem With Turbochargers
Turbochargers have their issues. Primarily, from a design standpoint, being powered by the gases from the exhaust, it tends to lack performance at lower revs.
That’s why most of today’s manufacturers use a double boost. Basically, a small turbo for low speeds (smaller thus faster to fire through the inertia) and a big one for high revs. We find this particular solution on some BMW engines and the V6 HDi.
Some cars like the old Mini Cooper S use a supercharger on their engines (or belt-driven compressor). Unlike the turbo, the compressor is connected to the timing belt. A notable example of this technology is the Kompressor line from Mercedes.
Finally, VW has the TFSI, which has the advantage of having a compressor and a turbo. Resulting in a very wide power range.
Because of anti-pollution laws, many vehicles will use turbocharged engines in the future., The cost of turbo maintenance has to be considered when buying a vehicle.
Do you know how often to rotate turns the turbine of a turbo?
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Tags: fixing turbo, loud whistle, turbo, turbo servicing
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