Hi, 

 

I have a Skoda Octavia Mk2, 2006, 1.4 petrol engine car.

 

Before a long 2000 km round trip, the car was overfilled with regular 95 octane petrol, so probably because of this I encountered a lot of problems.

 

-the check engine light came on after 300 km drive, showing misfire problem, but after clearing it with an OBD2 scanner it went away for a while. But kept coming back on around every 200-300 km. The mileage was still normal, although the car felt less powerful and noisier.

 

-after getting home from the long trip, consulting a mechanic, he erased the error codes for ignition problems and in the last 200 km there were no additional check engine light warnings. He only recommended to use higher octane petrol to use( I am still trying to do it), to see what happens. However the car is louder in idle, and all around is noisier, sounds like a little bit like a hissing sound, I start hearing it around 50 km/h speed and a little bit of shaking.

 

-after turning off the engine I hear a pulsating sound from the gas tank, and when I remove the cap, the sound goes away.

 

Any idea what might causing the problems? 

 

There is no error codes right now, but I am afraid something will go off soon. Could it be some kind of leak? Contaminated charcoal canister, dirty gas cap, some valve that needs replacing? 

 

Thanks for the help

Welcome.

I do not know your car type, but be venting the tank i suspect it is the charcoal canister that is the issue.

1 minute ago, Roottootemoot said:

Welcome.

I do not know your car type, but be venting the tank i suspect it is the charcoal canister that is the issue.

 

Is this something that can return to normal over time? Or definitely needs to replace something?

What was the code that was cleared?

13 hours ago, chrisund123 said:

What was the code that was cleared?

I can't recall now, some problem related to to ignition in the cylinders. Maybe 3-4 error codes.

On 15/08/2019 at 00:09, Sanya said:

I can't recall now, some problem related to to ignition in the cylinders. Maybe 3-4 error codes.

Hi, just to follow up, I did ignore this problem,  but the MOT test is getting closer and I want to fix it. 

 

So, this problem started in August 2019. After the misfires and cleared error codes there were no more error codes for a long time. Only the louder engine, but normal fuel consumption. New engine misfire happened in around February, after around 200km drive at highway speeds. The error codes were: P0300, P0302 and P0304. We cleared it with a cheap OBD devices and did not see it anymore. But the loud engine noise still persist, maybe a little bit of shaking, but when I am at the passenger seat, I do not feel it. I do not hear anything weird from the charcoal canister though. The belts or pulleys are a bit loud, but they were always this way, even after a pulley change.

 

Any ideas, what might be the main cause of the loud engine and occasional misfire? I am using 95 or premium 95 fuel. Did not try with higher octane yet. 

 

 

Try new spark plugs. Check air filter condition.

Edited 11 May, 20206 yr by xman

3 minutes ago, xman said:

Try new spark plugs. Check air filter condition.

Thanks. Does the both of the mentioned problems contribute to the louder engine noise?

With ignition misfires, always check plugs, leads and coils first.