[PaddleShifter]

Originally Posted by hserus

What is the next step here? All the obvious stuff seems to have been tried so far.

MAF sensor, spark plugs, throttle body, PCV, canister and fuel lines are already done.

I hope air filter and fuel filter are replaced timely.

If these basic things are in order, then the next troubleshoot step involves checking/cleaning the fuel injectors.

If even that does not work, then the remaining steps are to check the pistons rings for wear and tear. But that would have given you an indication in the form of power loss.

The O2 sensor and MAF densor issues give check engine light so those are ruled out.

A misfiring engine will sound very rough on idling. I dont think you are exprriencing any rough idling or loss of power.

[WorkingGuru]

Hi, did you happen to get an engine compression test done ?

If yes, how much should the pressure be and what has it come down to ?

[Jeroen]

Originally Posted by hserus

Reopening a very old thread

I have a 2011 city automatic (ivtec), and of late its mileage has been barely 5 kmpl. Same hiss of petrol vapour on opening the fuel cap.

Things done so far -

As you can read in this thread it is quite normal for all modern cars to have some hissing when opening the fuel cap. Unless it is exceptional and there are other problems it is perfectly normal for some hissing to occur when opening the fuel cap. Modern fuel systems are slightly over pressurised and that pressure remains in place for a while after you switch off the engine.

3. Changed the pcv valve and cleaned the pcv breather hose

4. New spark plugs

5. Cleaned mass airflow sensor

6. Cleaned throttle body

7. Starter motor serviced due to starting issues (most probably unrelated)

None of the above have anything to do with the hissing. Waste of time and money I afraid.

Not sure what was wrong with your fuel cap? Again, the system needs to be pressurised. If anything if the fuel cap doesn’t seal Properly you will most likely get a check engine light!

Jeroen

[hserus]

Originally Posted by PaddleShifter

I hope air filter and fuel filter are replaced timely.
checking/cleaning the fuel injectors.
If even that does not work, then the remaining steps are to check the pistons

The engine is smooth. Air filter is new. This model of city seems to have an inbuilt fuel filter rather than one that you change a cartridge for, and I can’t locate any replacement fuel filter on eg Boodmo

Originally Posted by WorkingGuru

Hi, did you happen to get an engine compression test done ?

There’s no power loss or jerkiness as you would expect with a compression loss, but this isn’t tested yet. So I am not entirely sure this is going to be injectors or loss of compression. Will still check.

Originally Posted by Jeroen

Not sure what was wrong with your fuel cap? Again, the system needs to be pressurised. If anything if the fuel cap doesn’t seal Properly you will most likely get a check engine light!
Jeroen

Sorry I wasn’t clear - I am troubleshooting low mileage in what is basically a bog standard 1.5 litre NA Honda engine. I thought the high fuel consumption was due to petrol evaporation, and the hiss of escaping fuel was a symptom. The fuel cap has four vents that were jammed and not closing properly so I ordered a replacement. Like in this one

Gates 31838 Fuel Tank Cap https://amzn.eu/d/hvn9inK

[Jeroen]

Originally Posted by hserus

Sorry, I wasn’t clear - I am troubleshooting low mileage in what is basically a bog standard 1.5 litre NA Honda engine. I thought the high fuel consumption was due to petrol evaporation, and the hiss of escaping fuel was a symptom. The fuel cap has four vents that were jammed and not closing properly so I ordered a replacement. Like in this one

Ah, sorry I misunderstood. But the hissing has nothing to do with your very low fuel efficiency.

First thing, I have said this a billion trillion times. Never start swapping parts (unless visually damaged or individually tested and failed) without having done a proper diagnosis. On any modern car that means hooking it up to a proper OBD scanner. Check for any errors. You need to get a scanner that can read generic and make/model-specific codes.

Also, most scanners have options for checking various engine parameters whilst the engine is running. The things you want to check are whether the engine is running rich. Short and long-term fuel trims. Lamba sensor correct operation. Fuel pressure and timing check. Is the ECU going into close loop or not?

Without the above, it is going to be guessing and trial and error all the way.

Loss (part) of compression on one cylinder does not necessarily mean a noticeable loss of power or jerking of the engine. The same can be true for an injector not working properly. A good OBD scan might give some hints though.

You might want to try the following. Start engine and drive it for about 15 minutes to warm it up properly. Let the engine idle. Pull the spark plug leads one by one. Obviously, the engine will run a little less smooth on 3 instead of 4 cylinders. But if there is a noticeable difference between any of them, or virtually no effect, you might have identified the cylinder which has a potential problem.

Don't run too long on 3 cylinder. Pull the spark plug lead, listen to the difference in engine sound and push it back on and onto the next and so on.

Good luck

Jeroen

[hserus]

Originally Posted by Jeroen

Never start swapping parts (unless visually damaged or individually tested and failed) without having done a proper diagnosis.

I will get the car scanned of course. But the maf sensor was dirty, and the pcv, evap canister did need replacement, plus the pcv breather hose was also clogged. This is a 2011 car and has run about 107k km

Compression and injector - I take your point and will check. Thanks!

[Gamemaztr]

Originally Posted by hserus

Reopening a very old thread

I have a 2011 city automatic (ivtec), and of late its mileage has been barely 5 kmpl. Same hiss of petrol vapour on opening the fuel cap.

Our 2015 Ertiga (Petrol) was also facing with a similar problem and no mechanic, even MASS technicians were able to find why it was happening. It would only happen in summers and the fuel smell would creep inside the cabin. Till the pressure was released or the fuel cap would be kept slightly open, the fuel smell (fumes?) would creep inside the cabin making it very nauseous. The fuel efficiency had also dropped by 2-3kms/lts

Eventually, upon close inspection, we found a very tiny hole just below the filler cap. We inserted a very thin but clean steel wire through it thinking there might be some sort of air hole which may have blocked it. However, at the end of the hole we could feel some flap opening and closing. It was completely jammed at the first instance and required some effort to reopen it. We tried to see if we can have a look at the flap but weren't successful. However, the incidents of fuel pressure building up in the tank reduced drastically would now happen only on very hot days with a long 5-6 hr drive. However, the fuel efficiency was back to normal after that experiment.

You may have a look if the City is equipped with some sort of hole like this and try. Make sure that you are not too harsh in doing this as it may puncture some important pipes leading from fuel tank to engine.

Also, it is possible that the fuel filter or the fuel pump may have become faulty. You need to check on that as well.

[GTE]

If the car has done over a 100k, unless it has been serviced very regularly it could be your piston rings. You will need to do a compression test to know more. BTW opening a tank is a very risky thing to do. A hiss when removing the filler cap is perfectly normal.

[hserus]

Originally Posted by Gamemaztr

However, at the end of the hole we could feel some flap opening and closing. It was completely jammed at the first instance and required some effort to reopen it..

Evap canister and this has been changed

Originally Posted by GTE

If the car has done over a 100k, unless it has been serviced very regularly it could be your piston rings. You will need to do a compression test to know more. BTW opening a tank is a very risky thing to do. A hiss when removing the filler cap is perfectly normal.

The car has been serviced on schedule at a Honda ASS. Other than suspension and AC cooling coil / compressor clutch pulley, nothing much else was the issue. Clean engine (no varnishing or anything)

[NomadSK]

Originally Posted by hserus

Same hiss of petrol vapour on opening the fuel cap.

This would be a normal phenomenon as Vapor pressure is build inside the tank, either on a hot sunny day or constant splashing of the gas inside the tank, during movement, which needs to be vented safely. Fuel caps have a built-in pressure and vacuum relief valve, Releases the pressure when enough gas vapors are produced (Hissing sound) and prevents in formation of vacuum in the tank while gas is sucked by the fuel pump to the engine.

[GTE]

The car has been serviced on schedule at a Honda ASS. Other than suspension and AC cooling coil / compressor clutch pulley, nothing much else was the issue. Clean engine (no varnishing or anything)

Some workshops do not change oil even when they say they have. This is done by lower level staff. I have been offered original VW boxes of oil at 50% of mrp. I suggest you remove the dipstick & check the color of the oil. Another indication is if you can see any sludge build up when you remove the oil filler cap.

[hserus]

Originally Posted by GTE

Some workshops do not change oil even when they say they have. This is done by lower level staff. I have been offered original VW boxes of oil at 50% of mrp. I suggest you remove the dipstick & check the color of the oil. Another indication is if you can see any sludge build up when you remove the oil filler cap.

I got this car six months back from a gentleman who is related to a fellow bhpian so this is a known car with known history. I still changed all the fluids (oil, coolant, brake fluid, atf fluid) once I got it into my hands.