Diagnosing 1.4 16v "BXW" engine problems

[finscout]

Hi everyone, I have a 2007 Fabia II 1.4 16v with the BXW engine, and it has a mysterious problem that local Skoda garage has been unable to solve.

Symptoms are:

 

• After startup, engine sometimes idles roughly with three or two cylinders, but goes to normal when I rev it up. After that it idles fine.
• Sometimes when idling rough after startup, engine does not respond to gas pedal, cuts off by itself or I have to cut it off and start again. Sometimes it takes up to four startups to get it running.
• Engine responds slowly to gas pedal in general when idling. There is like a 0,5-1 sec. lag before it starts revving up, first shaking and then smooth. Once it cut off while driving, when I tried to rev up quickly when idle
• VAG-COM shows NO faults
• Spark plugs are new, temperature sensor is new
• Once the engine management light appeared when just driving along 60mph. Foremost lambda sensor was reporting that mixture was too lean or something like that. Don't kow the exact sentence, I'm just translating it from Finnish... Has not appeared again.

The symptoms are ONLY related to starting up and idling. The symptoms don't appear every time, but lately it has been worse. Otherwise the car runs fine, revs up to 6000 nicely, and I can accelerate with gas pedal on the floor to 100 Mph without any problems.

 

Starting the car feels sometimes like trying to get my wife's 105E Anglia running when cold, and not using enough choke.

 

Any ideas? Could it be the ECU or fuel pump?

 

Is it even possible that coils / wires / nozzles only give symptoms when idling and starting up, but otherwise work fine?

 

The car has 77 k miles on the clock.

Edited 24 May, 2014 by finscout

[fordfan]

Possible vacuum leak as it's been showing a lean mixture.  It's possible that EGR valve isn't closing properly which would upset the vacuum in the inlet manifold.  An easy way to check would be to blank off the EGR pipe at the manifold and try it.

[finscout]

Thanks for your reply fordfan. Sorry I'm not fully aware what part do you exactly mean, could you specify from the attached image?

 

 

Today it took five startups to get the engine running. Drove 10 miles and after that, I did six repeated startups and everytime it started fine.

 

Seems like sitting overnight or for a work day is what makes the problem appear.

Edited 24 May, 2014 by finscout

[Ootohere]

Is there an Inline Fuel Filter, and if so, has it been replaced?

[finscout]

The fuel filter is located underneath the fuel tank, near the fuel pump. Both relatively cheap parts to replace, I think I'm going to get them both replaced to see if it helps anything. The fuel pump sounds normal though... 

 

[fordfan]

I'm not too familiar with the BXW.  I think that you want to look at anything which can affect the vacuum in the inlet.  The brake servo pipe is one thing item 11 on your picture, the Exhaust Gas Recirculation valve isn't shown on your picture, from experience on the older 16 Valve engines I've seen them play up and give running, starting and idling issues.

[finscout]

I tried to find the EGR from partscat.info drawings but that was all I could find, does the BXW even have one?

[finscout]

Changing the fuel pump and fuel filter solved the problem. The fuel pump check valve was probably broken... All working fine now, MPG is also better than before

[skdfb2008]

Hi,

 

I have a Skoda Fabia II , manufactured in 2008 with 1.4 litre petrol engine (engine code: BXW) in it. When it is warmer outside (the temperature is above 22-25 °C) it only starts after 3-4 try. To be honest, at first tries, the RPM goes up to 5-600 for 1-2 seconds, then the engine stalls. This is repeating 3-4 times, and after that finally the engine starts without any problem and runs smoothly. Anyway, the power and torque are OK, the oil and fuel consumption are average and the battery is new, the coolant temperature sensor was replaced. I always feeding it with octane 100 premium gasoline with no ethanol in it. The strange thing is that, this only happens in summer when the car stays outside under the Sun, in winter it starts immediately during ignition. I have a clue that this might be in relation with the hot weather, but I have been investigating this for almost a year and still no results... Do you have any idea what could be the problem? Fuel pump? Spark plug? Ignition coil? Vent valve? Please help!

 

Thank you in advance!

[rum4mo]

This should sound like a stupid suggestion, but it seems that this sort of behaviour can be caused by a faulty EVAP valve - I can't say why, but a few Ibizas with that engine that had that problem cured it by replacing the EVAP valve, be aware that there will not be a fault code logged to support this.

 

Edit:- sorry for not making it clear, but your idea that it might be the vent valve is correct, ie EVAP.

Edited 7 May, 2018 by rum4mo

[skdfb2008]

Thanks for the suggestion, I'll try it. Btw, what is the purpose of the EVAP valve? How it is connected to fuel system?

[rum4mo]

The fumes of petrol are now not allowed to be vented to atmosphere, so they must be drawn into the engine and burned, the EVAP valve controls when this purging happens, ie it only occurs under certain conditions.

 

Edit:- there is a carbon canister in the car and that absorbs the petrol fumes, the EVAP valve is connected to that canister and purges it.

Edited 7 May, 2018 by rum4mo

[skdfb2008]

Oh, I see. So something goes wrong with this when it is warmer outside?

[rum4mo]

Either that or the engine becomes intolerant to this extra fuel being drawn into a cold engine in warmer weather, I'm guessing that if it is faulty, it either is not opening when asked or staying open or slightly open when it should be closed.

 

Portugal seems the typical area of the world where this affects this engine starting in summer weather.

 

Edit:- remember that there will be more petrol fumes/vapour in the system in higher temperatures and the engine does not need so much fuel enrichment when cold starting at higher ambient temperatures - so everything works against you if this valve is slightly open at all times.

Edited 8 May, 2018 by rum4mo

[skdfb2008]

Thank you rum4mo for the nice and comprehensive answer.

 

May I have one more question? 

Where can I found this EVAP valve under the bonnet and could you recommend a method how can I make sure that this stuff is wrong? Does it have a special sound during ignition or any sign on it outside?

 

Thank you!

[rum4mo]

Sorry for missing this posting!  

 

Okay, I have not got the Ibiza with that engine near me at the moment, my daughter who owns it lives 10 miles away, so unless I can find anything out either in my Polo Haynes manual, or the thread on the Ibiza forum where I think someone asked that very question.

 

So how can you tell if it is working okay, well I don't think that it will make any noises when the ignition is on with the engine not running, neither do I think that it will normally be getting activated when the engine is running and not under certain load and RPM conditions.  I'm not sure that applying 12V to the valve when you find it will be very helpful as in use it will just be getting pulsed - so that will only leave trying to blow through it once you have located it and removed its hoses.  I have a strange feeling that it is on the RHS of the car and mounted in a very compliant rubber mounting with an I/P pipe and an O/P pipe and an electrical cable!

 

Edit:-       https://forums.seatcupra.net/index.php?threads/n80-purge-valve-location.415856/

 

 

Edited 11 May, 2018 by rum4mo

[rum4mo]

Well any further forward this this issue?

[skdfb2008]

Hi,

 

In my country the mentioned part is quite expensive so i have to clean it first on weekend, if it doesnt fix the problem just in that case I 'll buy a new one.

 Do you have any documentation about how to detach the valve from the pipes? Do I need special tool?

 

Thank you

[rum4mo]

No, sorry, but I would think that you would either need to carefully open up the crimped sections of these clips or cut them and buy new easier to fit clips.