What is overrun engine?

Overrun said. … 5. ( Engineering / Mechanical Engineering) (intr) (of an engine) to run with a closed throttle at a speed dictated by that of the vehicle it drives, as on a decline.

What causes engine overrun?

Potential causes



Dieseling can occur for several reasons: Built-up carbon in the ignition chamber can glow red after the engine is off, providing a mechanism for igniting unburnt fuel. Such a thing can happen when the engine runs very rich, depositing unspent fuel and particles on the pistons and valves.

Is Overrun bad for your car?

You are blowing incompletely burnt or unburnt petrol through the exhaust system. Misfires can damage cats let alone that volume of fuel and as the cats are part of your car, yes it damages your car.

What is exhaust overrun?

it is just a term for when the engines rpm is higher than the throttle possition can sustain and thus the revs drop. This is used obvioulsy in engine breaking as it has the effect of the engine wanting to slow back down. popping and banging from the exhaust isnt overrun as such. It is a result of overrun.

What is turbo overrun?

Over-running of turbocharger means, it runs in more RPM than designed in a particular load. Turbocharger Over-run happens in constant pressure turbo-charged engines. Causes: > Due to the fire in scavenge space. … Due to the fire in exhaust trunk because of the oil accumulation.

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What causes engine Dieseling?

In a gasoline engine with a carburetor, dieseling occurs when the engine continues to run even after you have shut off the ignition. The hot spark plug continues to detonate the fuel, and the carburetor simply supplies the fuel, because it is not always controlled electronically.

Why do cars pop and crackle?

That crackle comes from excess, unburnt fuel burning and exploding in the exhaust pipe. Everything from a light crackle to the full gunshot-like sound of a “bang-bang” Anti-Lag System (common in Rally cars) to shooting flames are all caused by the fuel burning in the exhaust that comes with running rich.

Why does my exhaust pop at idle?

Now if the car sounds like a real slight miss or pop at idle, it could be a burnt exhaust valve or an exhaust valve not fully seating and seal properly. The “burbles” or “popping sounds from the exhaust” as you have crassly put, are a result of exhaust back fires. …

What causes exhaust burble?

Some cars’ exhaust systems will produce an odd burble or bubbling noise. For the most part this is deliberate when it occurs in vehicles upon acceleration, but not always. … The burble is in actual fact a series of lean misfirings caused by this timing which rumble out through the exhaust system.

Can a backfire damage an engine?

Backfires and afterfires are worth paying attention to since they can cause engine damage, power loss, and decreased fuel efficiency. There’s a variety of factors that can cause your car to backfire, but the most common ones are having a poor air to fuel ratio, a misfiring spark plug, or good old-fashioned bad timing.

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What is overrun tune?

Overrun Crackles – Pop and Bang Tuning



Pops and Bangs, or Crackles as the OEM call it (yes, it’s that common on production cars that even the manufacturers have a name for it!), is simply a calibration feature within the ECU where we set up a specifically targeted, very lean misfire once you lift off the throttle.

What happens when you overspeed a turbo?

Overspeeding is when the turbo rotates at a greater speed than its operational limits and can push the turbo beyond its safe operating parameters, causing it to fail by damaging the turbine or compressor wheels and bearings.

Can turbocharger cause car fire?

Turbocharger over-runs, resulting from explosive fires that occur in the exhaust gas manifold and sometimes causing catastrophic failure of main diesel engines, have been a persistent problem for many years.

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