Q: VW Polo running on three cylinders?

asked by on

VW Polo running on three cylinders. Replaced coil pack, plugs, leads and injector on cylinder 4. Still doing it, could it be the head gasket? When ticking over I notice the idle speed slightly increases and decreases by it's self?

My car has 19000 miles.
My car has a manual transmission.

This is possibly a sign of an intake air leak creating a lean fuel condition. When this happens, this causes an imbalance in the air/fuel mixture inside the cylinder causing the misfire, which can also cause the engine idle to fluctuate as you have described. As the electric pulse continues to be delivered to all spark plugs, the remaining cylinders fire normally as the proper air/fuel mixture provides the perfect explosion inside the cylinder. When the 4th cylinder receives the same spark and fuel, but additional air, this leans out the mixture due to excess oxygen being added to the fuel being ignited. I would recommend having an expert from Your Mechanic come to your location to take a look at the vehicle to properly diagnose the idling issue and repair.

Was this answer helpful?
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
  1. Home
  2. Questions
  3. VW Polo running on three cylinders?

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: Installing performance brakes

Hi, thanks for writing in. It all depends on the performance parts that are being installed. You suggest following the recommendations of the kit manufacturer. If the rotors and pads are the same size as the original equipment, then you...

Q: Driver side door won't close

If the door will not close all the way no matter how hard you shut the door, the door latch may be damaged. To replace the door latch would involve the removal of the door panel, the noise canceling material,...

Q: hi, what can i change on my 2006 4runner to give it smoother ride on bumpy roads

There can be some gains in comfort by changing the tires to, for example, top rated tires as tested by Consumer Reports. The best thing to do is review Consumer Reports' tire ratings and recommendations for the particular tire type...

Related articles

What Causes Hoses to Leak?
While the largest part of your engine is mechanical, hydraulics plays a significant role. You’ll find fluids at work in a number of different areas. Your car's fluids include: Engine oil Transmission...
How Long Does a Distributor O Ring Last?
The distributor is part of the ignition system in your vehicle and its purpose is to route high voltage from the ignition coil to the spark plug. The spark plug then...
P0240 OBD-II Trouble Code: Turbocharger Boost Sensor B Circuit Range/Performance
P0240 code definition Turbocharger Boost Sensor B Circuit Range/Performance What the P0240 code means P0240 is an OBD-II generic code triggered when the Engine Control Module (ECM) detects the intake boost...