Hi!

In summary:

I have an engine, that runs very roughly, dies when idling, car not usable. I can crank it, but if I let it idle, it will die in a few seconds. By pushing the gas pedal, I can keep it running, but the engine shakes horribly (probably ugly misfires), and no power at all.

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

(You can check this other thread in which I describe the same problem: link )

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

- MAP sensor cleaned, air pressure checked in VAGCOM = 1 atm

- fuel pump checked: pressure normal (3bar), hold pressure OK (-0.5bar / 10min), fuel flow rate 1 liter / 30 sec

Not yet checked:

- EGR valve (might need a clean, but don't think it causes my problem)

- O2 sensor (How can you check this ???)

Now I have a very strong feeling that the above problem is caused by a faulty hall effect sensor!!!

The nature of the problem suggested to me that the fuel pump might be broken, but the same symptoms and misfire can be equally explained by a faulty camshaft sensor reporting faulty position readings to the ECU.

Also, in the past 2-3 years I had those unexplainable occasional highway power loss syndromes (this is a very frequent problem reported on these forums, but Ive seen no reported solution so far), that may also be related to faulty camshaft sensor. My theory is that the earlier intermittent sensor problem has finally ended up in a totally broken sensor.

So my question is:

How frequently do these camshaft sensors die, and what are the symptoms? Do you think my problem can be connected to it?

Edited 27 December, 201015 yr by bnud3

What engine do you have?

What engine do you have?

1.4 16V BBY

Have changed a fair few but normally flag up a fault code.

What are your compressions like?

What are your compressions like?

I've never tested it, and no experience in how to do it. Is it a DIY job for a non mechanic? I just hope that the engine is mechanically all right .

To be fair with any running fault no matter how complicated the system its always best to check the basics.

Sounds like you have air and fuel sorted so all you need is a spark, compression and it all to happen at the same time and it should run.

Get yourself a cheap compression gauge and check them, its just a case of taking the plugs out and screwing in the gauge and turning the engine over.

Have you checked cambelt timing also?

Thanks for the advice.

I will probably do the compression test after replacing the camshaft sensor which probably needs to be replaced anyway.

Do you have any experience with this highway sudden loss of power symptom described in this thread: http://briskoda.net/forums/topic/161463-faulty-camshaft-or-crankshaft-position-sensor-or-something-else/

I had the very same phenomena occuring occasionally during the last 2-3 years.

Have not checked cambelt timing. Is there some simple method or kit to check cambelt timing?

Is this missing ???? or does it sound different.

Have you tried pulling one ht at a time to see if it changes anything.

Is this missing ???? or does it sound different.

Have you tried pulling one ht at a time to see if it changes anything.

What do you mean by "missing"?

This engine has spark plug coils, high-tension is creared only right at the plugs. I checked the coils with a multimeter, and they seem good.

What do you mean by "missing"?

This engine has spark plug coils, high-tension is creared only right at the plugs. I checked the coils with a multimeter, and they seem good.

Is your engine missfiring.....or is it a different kind of bad idle.

Is your engine missfiring.....or is it a different kind of bad idle.

Yes, I think it's misfiring.

But interestingly, no fault codes in VAGCOM.

I'm going to replace the crankshaft (=speed) sensor and the camshaft sensor. If this does not help, I will check the compression.

Does anybody know what is the solution for the very common momentary engine cut-out symptom at steady speed (usually highway) ?

Is it the crankshaft or the camshaft sensor?

You can find lots of hits for this exact problem, btw it seems to be a common VW issue, not just Fabia. Just a few:

http://www.ilexa.co.uk/forum/index.php/topic,15476.0.html

http://briskoda.net/forums/topic/161463-faulty-camshaft-or-crankshaft-position-sensor-or-something-else/

http://briskoda.net/forums/topic/88425-14-16v-revs-momentarily-dying-on-the-motorway/

If it runs OK above tick over, then I would think it has to do with fuel/air mixture, either not enough or too much of one.

There are pipes attached to the fuel system that may have split/ perished where you can't see them, or fuel feed is partially blocked.?

Before trying to second guess what it could be, I would suggest take it to garage and outline problem you have.

This may not be the cheapest route to take, but you would save buying and fitting stuff you perhaps don't really need.??

Good luck.