Pictures of pistons through spark plug hole. Looks O.K.?

[bnud3]

Hi!

I am changing the spark plugs for the first time in a fabia 1.4 16v with 70000 km mileage.

I took two pictures of the pistons through the spark plug hole. The top of one piston is covered by this black soot/sludge, the other piston is covered only partially.

Do you think it is totally normal, is it as it should be?

Here is the old plug. Does the old plug look also O.K.?

Thanks!

[2SkodaFamily]

I'm no expert, but I would say that the old spark plug looks a bit sooted up to me. Doesn't look like it's burning the mixture cleanly. What's your air filter like?

[blueR36]

Pistons look a bit coked up to me , plug not too bad.

[mudyf0x]

as above but dont forget to check gaps on plugs before re fitting

[Lew_VRS]

I'm no expert, but I would say that the old spark plug looks a bit sooted up to me. Doesn't look like it's burning the mixture cleanly. What's your air filter like?

i'd say possibly running a little rich, just a touch

[veedweeb]

i'd say possibly running a little rich, just a touch

I agree.

It could be caused by a few things - faulty O2 sensor, dirty air filter, faulty coolant temperature sensor etc etc.

However, if you ran the engine from cold just before taking the plugs out, that could explain the fouling.

[bnud3]

I agree.

It could be caused by a few things - faulty O2 sensor, dirty air filter, faulty coolant temperature sensor etc etc.

However, if you ran the engine from cold just before taking the plugs out, that could explain the fouling.

Thanks for all answers.

Actually, all of you have some good points there, because the engine is not running well. It runs very roughly, and it dies when idling. Overall the car is unusable at the moment.

I started to repair as a DIY job: I already changed the coolant temp sensor, changed the fuel filter, checked resistance of spark plug coils, none of them helped. Now I am changing the spark plugs as my next guess.

Air filter was changed 1.5 years ago, but I will check it anyway.

So you say a faulty O2 sensor could also be a possible cause? At the moment I also suspect the fuel pump.

VAGCOM did not show any faults. Is it possible to tell with VAGCOM if for example the O2 sensor readings are not quite correct?

Any further advice appreciated!

Edited 10 October, 2010 by bnud3

[veedweeb]

Any further advice appreciated!

I'd change the air filter as a matter of course - it's one of those things that can only make matters better.

I'm not too familiar with VAG-COM, but a faulty O2 sensor would probably register a code on the ECU

There is a way of testing sensors and if you google it you should find out how to do it - I can't remember enough of the details to say for sure now though.

EDIT: just had another thought - rough running and idling can be a symptom of problems with the EGR valve so it could be that too, maybe?

Edited 10 October, 2010 by veedweeb

[bnud3]

I also got some hints that maybe the ECU connectors should be tested and cleaned. When I get to finish the spark plugs I will check those remaining things (ECU, air filter, O2 sensor via VAGCOM, fuel pump (still no idea how to check this)).

OTOH, I checked some pictures regarding the used spark plug:

Accrording to this http://www.spark-plugs.co.uk/pages/technical/diagnosis.htm my old spark plugs look o.k. to me, weared of course after >70000kms.

I also checked what piston tops used to look like:

Found these posts, scroll down to the pictures:

http://forums.vwvortex.com/showthread.php?1581500

another post with pictures http://forums.vwvortex.com/showthread.php?4054146

Comparing to the above, my piston tops could be normal (at least I hope so).

[ap0gee1978]

...the engine is not running well. It runs very roughly, and it dies when idling...

MAP sensor.

[ap0gee1978]

...the engine is not running well. It runs very roughly, and it dies when idling...

MAP sensor. If it's an incipient fault rather than totally dead, you may not get fault codes logged.

FWIW, before I replaced the one on my wife's car, it had the 'classic car carburetor' overfuelling smell after it had been driven.

[bnud3]

MAP sensor. If it's an incipient fault rather than totally dead, you may not get fault codes logged.

FWIW, before I replaced the one on my wife's car, it had the 'classic car carburetor' overfuelling smell after it had been driven.

Thanks for the answer.

Where is the MAP sensor on Fabia1 1.4 16v (not MPI) motorcode BBY?

Here is an old thread of mine with a few pictures where some time ago I tried to figure out all sensors I could see (8 pieces actually) in the engine area http://briskoda.net/forums/topic/131944-start-engine-first-time-after-6-months/page__p__1655334__fromsearch__1entry1655334.

Maybe someone could point me the MAP sensor on those pictures?

I suppose a MAP sensor can be tested with an ohm meter, right?

To tell the truth my engine problem is not intermittent. Whenever I start the engine, and let it idle, it will die right away if I don't rev it up a bit. And also during revving it is not running well, it shakes, no power, so the car is totally unusable at the moment.

But I will check the MAP sensor if it's simply a multimeter measurement.

Edited 12 October, 2010 by bnud3

[ap0gee1978]

The test is to see if it runs any worse with it disconnected - if not, it's knackered!

It sticks in the inlet manifold on all normally-aspirated cars, regardless of model - MAP stands for Manifold Absolute Pressure.

HTH

[_VRs_]

How are the ignition leads? I had an Arosa 16v and they were all starting to pack up after 60000 miles and 5 years.

[bnud3]

UPDATE:

I fiinished checking some more things.

So in summary:

I have an engine, that runs very roughly, dies when idling, car not usable.

Unfortunately, no faults indicated in VAG-COM at all.

I have done the following so far:

- coolant temp sensor changed

- fuel filter changed

- throttle valve cleaned last year. Now I just checked that it is not stuck, valve moves when pushed with finger.

- resistance of spark plug coils checked, all 4 is equivalent

- spark plugs changed

- air filter cleaned with compressed air

- ECU unit connectors disconnected, checked, reconnected

To be checked (in order of probability):

- MAP sensor

- fuel pump

- EGR valve

- O2 sensor

- ignition lead (no idea how to check this)

Any further tips/advice greatly appreciated!

Regarding the MAP sensor: I'm going to start engine with MAP sensor connector unplugged as suggested by Ap0gee.

Also I'm going to check VAG-COM measurement groups that display air pressure data. (I still don't exactly know which group should be checked, and how the indicated valued should be interpreted. What are the correct ranges?)

I located the MAP sensor, it's the sensor number 4 (behind the oil dip stick): here

Should I buy a new sensor, or is it just the carbon deposits that has to be cleaned off?

Regarding fuel pump: is there any home method to check this? The fuel pump has to deliver 3 Bars pressure.

Thanks!

Edited 18 October, 2010 by bnud3

[bnud3]

I tried to start the engine with MAP sensor disconnected: it wouldn't fire up, but it throwed 2 DTCs (something like Manifold pressure sensor ground, and Intake air temperature value too high). VAG-COM showed 2 mbar for Manifold Pressure value.

When I reconnected, it wouldn't start either.

VAG-COM meas. block group 002 field "intake manifold pressure" says: 995 - 1001 mbar (the exact value varies between these boundaries). I think the value is correct, corresponds to 1 atmosphere.

I am not convinced by this that the MAP sensor causes the problem. Either connected or disconnected the engine won't idle. I think Apogee's point was that if the engine is much worse with MAP sensor disconnected, then the sensor should be all right. But in my case, the engine just cannot be worse because it is totally bad already.

Question1: if you disconnect the MAP sensor, should the engine start up at all?

Question2: can a dirty EGR valve make the engine not start at all?

Question3: can a faulty fuel pipe cause the same? How can I check if the pump delivers the correct pressure (3bar) ?

Thx

[ste372]

does the car not idle at all or just when u first start the engine from cold?

could be egr valve stuck open thus not allowing enough clean oxygen through to let the car idle from cold.

[Tech1e]

I would be looking at the egr valve, have you tried resetting it (and the throttle body) with VAG COM?

[bnud3]

OK, I took out the MAP sensor, cleaned it thoroughly, put it back: nothing has changed. The sensor itself was a bit dirty.

As I observed wIth disconnected sensor, the engine won't start at all, just cranks. With MAP sensor connected it starts, idles for a few seconds (very roughly) then stalls.

So, I think MAP sensor is ruled out (for the time being).

[bnud3]

does the car not idle at all or just when u first start the engine from cold?

could be egr valve stuck open thus not allowing enough clean oxygen through to let the car idle from cold.

It does not idle at all. When I first start it, it idles for longer (although very roughly), maybe for 10-15 seconds, then stalls. When I try to crank it for the 3rd ot 4th time in a row, it won't fire up.

I will check the EGR valve. Is it an easy job?

Interestingly, noone mentioned the fuel pump yet. Can it not be the fault?

Thx

[bnud3]

I would be looking at the egr valve, have you tried resetting it (and the throttle body) with VAG COM?

Hi,

The throttle body, I have cleaned it a year ago, and reset it. But now, I did not cleaned it, I just gave him a reset through VAGCOM.

The EGR valve will be checked next. (At least I have to rule it out, because I would not like to buy a new fuel pump in vain :-))

How do you do the EGR valve in VAG-COM?

Thx

Edited 23 October, 2010 by bnud3

[Maris]

Probably I’m experiencing same with my car, but I have 1.4 mpi engine. It fails to start, but if throttle pedal is slightly pushed it starts, but operation is not smooth and it stalls if pedal is released. Till yesterday it was intermittent fault. Ignition, fuel system, engine sensors checked, everything good. Today I find out that cylinder No. 2 compression 0 psi, and one of 2. cylinder valves is stuck open. I don’t know why yet, but it doesn’t move when I hand crank the engine. I don’t know how it’s possible, but as I sad it was intermittent fault.

To be honest this is only one of problems I have experiencing: some coolant loss intermittently, mayo on oil filling cup, fuel tank evaporation control system fault registered by ECU.

[ap0gee1978]

I'd say the first fault was a failed MAP sensor, although it may or may not be simply down to no compression on no. 2 cylinder (broken pushrod or valve spring, perhaps?) Coolant loss is probably rad fan sensor or rad itself (the coolant can form a Radweld-like scab if the hole's only very small). Last two probably failed coolant evap temp sensor. I can help with the sensors if you need it.

[Maris]

Valve spring is ok, pushrod isn't broken maybe bent, I don't now yet. Lucks like hydraulic tapped is stuck or broken or ... Pushrod doesn’t move when engine hand cranked and holds valve in open position.

[bnud3]

Hi Maris,

You took off the cylinder head?

I still don't use the car, use the other. I will probably take it to a service station soon, because I have no ideas left. Although I'm quite disappointed after having checked lots of things.

In the meantime I did some more checks, the most important one being the fuel pump. I've been strongly suspecting the fuel pump up to now, but no luck.

I connected a gauge to the fuel filter output line. The fuel pressure is good (3bars), the pressure loss after switching off the pump is under 0.5bar after 10mins.

The fuel flow rate is about 1 liter / 30sec, way above minimum.

One last idea: Can alternator fault cause such symptoms? That is, the engine is trying to start on sole battery power (I've recharged it to full since), without the alternator delivering the 14V charge. In theory, can the engine run on sole battery power, for a few minutes at least?

Edited 27 December, 2010 by bnud3