Hi All,

 

I have just joined this site as my Skoda Fabia 1.2 3 cylinder HTP is causing me a proper headache.

 

I've had the car for just over 8 weeks now and pretty much since dayone it has been stall or dropping revs whenever I am idle or putting the clutch down to change gears. I have had it going back and forth bewteen my local Garage, local Skoda shop and the person I brought it off. The only thing they think could cause it was the throttle body, or fuel filter. I have had the fuel filter changed as it recked of petrol right after filling up and driving around.

 

The Throttle body has also been cleaned which has stopped the stalling fault when the engine is cold, but if the car has been sat in the sun or driven about (engine has warmed up), as soon as I come to a stop or go to change gears I can see the revs dropping and sometimes cutting out (starts up fine most times, sometimes it won't get to 1000rpm and cuts out again).

 

Looking around and on different websites people are pointing towards an ECU fault (fingers crossed it's not as thats not cheap...)

 

Has anyone on here had the same or similar issue and could shed some light on the situation as I want to keep the car but I would like to drive it with out fear of cutting out.....

 

Thanks,

 

 

A little more info please.  What year, what engine code (6-valve is either AWY or BMD, 12-valve will be AZQ or BME), what mileage? Edit, sorry, those engine codes would apply if you were talking about a Mk1 1.2, I was getting mixed up about which subforum I was in. 

I presume you have no fault lights on the dash, or you'd have mentioned that?

Any of the garages you've taken it to done a scan and got any fault codes out of it?

ECUs tend to be more reliable than most of the bits they're connected to.

Hi,

 

Thanks for the reply

 

It is a 57 reg and only done 61K miles.

No warning lights when driving, when it stalls all warning lights come on like I've just turned the key once.

Yeah the garages have ran tests and no error codes showing for anything.

 

Not sure if it's related or by design, but if I have my main headlights on and the engine cuts out my main beam dies and goes to side lights until I start the car again.

Have you had the battery and alternator checked? Sounds like low voltage. Cars are quite sensitive to the voltage level these days and all sorts of mayhem can be seen with low voltages. If its a 57 plate on the original battery then this could be quite possible. A cell in the battery could be faulty. 

I will look at getting a new battery before the weekend.

 

I was going to have a bit of mess about with it on the weekend anyway.

 

How hard/easy will it be to check the alternator myself, I'd rather not waste more money on my garage looking at it, if I could do it myself.

 

I am also going to give my spark plugs another clean, although I'd hope they would of done that when cleaning the throttle body.

Multimeter with 20 Volt dc range selected, probes on each of the battery terminals. Take readings first thing in the morning, before and after starting the engine. Hope to see 12.4 or more before starting engine, and 14.2 approx. when running.

Depending on the voltages you read, this may provide useful info about battery and alternator.

I'll pick one up today after work and test first hting tomorrow morning and update

 

I am also getting a temperature monitor for my ECU as there is a common fault with too much fuel being pumped into the engine when warmed up (costing me £15 so worth a try)

Check the brake servo vacuum pipe for splits at both ends. This would allow air to be drawn in and cause havoc with idling. Its the stiff plastic pipe running from the servo to the inlet manifold.

Other possibly diagnostic stuff:-

What revs is it idling at (cold) and hot (if possible)? Anything under 750 hot and there's your issue; the idle speed is too low.

Ken,

 

It is roughly idling (cold) at 1000rpm, somtimes it jumps upto 1500rpm when first started.

 

When warm it stays bewteen 1000rpm and 500rpm with random jumps backup. (about 5 out 10 times when it hits 500rpm it will cut out)

I'll pick one up today after work and test first hting tomorrow morning and update

 

I am also getting a temperature monitor for my ECU as there is a common fault with too much fuel being pumped into the engine when warmed up (costing me £15 so worth a try)

Do you mean the coolant temperature sensor? (you must, I think)? That makes sense.

A 'temperature monitor for my ECU' sounds like something you might use to see how hot the ECU itself is getting, which makes less sense (to me).

 

If it has an EGR valve, that might be sticking in an open state, which would cause idling/cutting out problems potentially.  But that ought to store fault codes in the ECU when it misbehaves, I would think.

Ken,

 

It is roughly idling (cold) at 1000rpm, somtimes it jumps upto 1500rpm when first started.

 

When warm it stays bewteen 1000rpm and 500rpm with random jumps backup. (about 5 out 10 times when it hits 500rpm it will cut out)

That's it then; the idle speed is set too low or the idle stabilisation has failed. When it's cold that's not an issue because of the cold enrichment.

Repeat: check the brake servo vacuum line at both ends, particularly the end behind the engine going to the inlet manifold.

What you describe is a classic symptom of an air leak post throttle body and a split vacuum pipe connected to the inlet manifold is a common fault. As the engine rocks, the pipe pulls back, opens the split and air is drawn in and the mixture weakens, ecu tries to compensate but if the leak varies, cant and the idle speed moves around and can often just stall or race.

In bad cases you can also get reduced brake assistance under repeated or heavy braking noticeable by the brake pedal going hard.

Edited 22 April, 201511 yr by xman

That's it then; the idle speed is set too low or the idle stabilisation has failed. When it's cold that's not an issue because of the cold enrichment.

is there an easy way to sort this? Is it just a matter of changing a few dials?

 

Do you mean the coolant temperature sensor? (you must, I think)? That makes sense.

A 'temperature monitor for my ECU' sounds like something you might use to see how hot the ECU itself is getting, which makes less sense (to me).

 

If it has an EGR valve, that might be sticking in an open state, which would cause idling/cutting out problems potentially.  But that ought to store fault codes in the ECU when it misbehaves, I would think.

To be honest I have no idea, it monitors how much fuel is being sucked through, as more is needed when the engine is cold and less is needed when it's warmed up.

The garage said when the engine warms up it should stop pulling as much fuel through, but with mine they think it might not be.

Repeat: check the brake servo vacuum line at both ends, particularly the end behind the engine going to the inlet manifold.

What you describe is a classic symptom of an air leak post throttle body and a split vacuum pipe connected to the inlet manifold is a common fault. As the engine rocks, the pipe pulls back, opens the split and air is drawn in and the mixture weakens, ecu tries to compensate but if the leak varies, cant and the idle speed moves around and can often just stall or race.

In bad cases you can also get reduced brake assistance under repeated or heavy braking noticeable by the brake pedal going hard.

I have noticed sometimes that the braking feels different in the mornings, I will check these out at the weekend.

 

it is softer in the mornings and feels quite tough and hard (no pun intended) after being sat in the sun or driven about.

Actually, I'm going to partially recant my last and say to check the servo pipes (by hand, not just visually) first, including squeezing any that have external fabric "armour" sheathes since they are known to fail internally and collapse under vacumn but look fine engine off.

Actually, I'm going to partially recant my last and say to check the servo pipes (by hand, not just visually) first, including squeezing any that have external fabric "armour" sheathes since they are known to fail internally and collapse under vacumn but look fine engine off.

I will look at this today on my lunch and update you with what it looks like or what happened, I will try and get some pics to include aswell.

Possibly too late to help, but here are some pics that might assist you in locating the pipe, and the four joints that need checking:

 

1. Where the hard plastic pipe joins to a fitting on the brake servo (big black round thing on the firewall at the back of the engine bay):

 

2. & 3. Where the hard plastic hose joins to the one-way/non-return valve, and the rubber hose on the far side of the valve connects to it:

 

 

4. Where the rubber coupling hose connects to the inlet manifold (just below the throttle body):

 

 

 

You may well find that things don't look exactly like this in your engine bay, as this is a 4-cyl BBY-code engine, but I imagine the component parts will be very similar.

Ive tried having a look at the pipes and all seems fine, granted I haven't had it jacked up. I've checked the thorrtle body pipes (or what I think to be the pipes) and can't see any visible cracks

I've bought a coolant temp sensor which I will be changing tomorrow morning when it's cold.

On 23/04/2015 at 13:26, Wino said:

Possibly too late to help, but he

Sorry to resurrect an old thread (do i ever do any different?!) but i would also like to try and replace this part as i'm having a similar issue.

The pictures you posted match my car perfectly Wino, but could you please tell me how it disconnects from the servo and inlet? Does it just pull off?

Thanks

I saw this thread and also thought of the thermostat. Might be sticking open or not opening etc. Long shot but they are cheap and easy to change in most cases. Haynes say they are almost certainly past their best if over five years old any how!

Leaks can be fiddly to find and also the dying battery scenario is a good likelihood on anything over five years too. The battery will say it is charged if you charge it but it will have slowly become weak and lower in capacity so what seems charged is really a half- flat worn out unit! Might make running unstable, starting difficult and generally, worth replacing if half shot.

5 hours ago, isambard said:

Sorry to resurrect an old thread (do i ever do any different?!) but i would also like to try and replace this part as i'm having a similar issue.

The pictures you posted match my car perfectly Wino, but could you please tell me how it disconnects from the servo and inlet? Does it just pull off?

Thanks

Yeah, as far as I remember. 

Thanks guys. I checked the hose over the weekend and got the part number but i can't see any cracks (looked quite closely) so at £35 I'm tempted to wait until I know more. I saw a couple of other hoses running to the Base of the throttle body, what are they? And what would be the poor running symptoms of a dodgy battery? The car starts fine :-)

just a long shot but in another forum which i was on...mk4vwgolf

a similar string of events were finally diagnosed by checking the earthing strap.

where it connects to the body

hope this helps

cheers

geof

In reply to jacobn. i have a 57 reg Skoda Fabia 2 . The car starts first time every time . Just had a major service at the dealership. When warm engine ticks over at 950 revs perfectly. when the engine is hot the tickover is very erratic jumping from 100 revs to 2000 revs . It has cut out completely and stalled in the middle of town quite a few times now . the battery is perfect .Skoda must know that there is a problem with the tickover on this model when the engine is hot !!!!! does anyone know what the problem is . Definitely not the battery !!!!