Fabia mk 11 misfire help

[Pappafox]

OK understood. 

[xman]

Sorry pappafox, but youre not being very descriptive of the symptoms and drip feeding bits of information doesnt help us to help you.

Lets recap

1. You have a misfire, with misfire codes coming up. After a while you changed all plugs and coil paks, seemed ok for a minute then lost power.....diagnostics shows problem on no.2.

What was the diagnostic code?
Did you reset the code and try again?

Remember unless reset by diagnostics, misfire codes take a considerable time and several restarts to reset themselves.....although the engine should still run fine...I'm trying to eliminate red herrings....

Was the "loss of power" accompanied by misfiring?

2. You found a split brake vacuum pipe (common at that age) and then remember to tell us that the car idle speed has been known to race from time to time......

 

You would need to replace that pipe anyway as its essential for brake servo operation and will cause running problems....fast uncontrolled idle and possible damage to valves due to weak mixture. Now ,with pipe changed, there is a loss of power above 3000 rpm.

Is this due to misfiring or just lack of response?

 

You imply that restarting the engine, restores the power? If thats the case, its a limp mode condition, and the error codes should be recorded or at least shown when the limp mode is active (before turning off the engine) A lack of revs might be a faulty or intermittent throttle pedal position sensor , an error will be there to read, provided you dont switch off the engine ....

 

Have you disconnected the battery ( to reset all variables in the ecu)?

If its something to do with throttle body, then there is a procedure for recalibrating it, I'm not entirely sure (a forum search might help)

I think it something like this:-

Turn off engine
Turn on ignition but dont start the engine.
Slowly depress the accelerator pedal until you fully depress it and hold for a few seconds then slowly release.
When fully released, turn off the ignition.
Restart the engine

 

(Following reset procedure by estateman)

 

PASSIVE METHOD: DO NOT TOUCH THE THROTTLE AT ANYTIME WHEN UNDERTAKING THIS METHOD. With the engine hot, turn off the ignition but do not remove the key. Next, simply turn on the ignition so the dash lights up, BUT DO NOT CRANK THE ENGINE or attempt to start it. Wait for 60 seconds then turn off the ignition fully. BUT DO NOT REMOVE THE KEY. Wait just 10 seconds and then restart the engine as normal.

 

 

 

Finally, you really need to give us accurate pressure readings, 10-20% difference is probably not significant. Loss of pressure is due to either ring/bore wear, or valve seat damage - not valve guide wear. Valve seat damage is the only one that would give loss of power/ misfire at elevated revs.

 

It would also help to know the service history, has the oil been changed regularly? e.g.  at least annually. I ask as there is a known problem with these engines as far as the chain tensioner is concerned. Poor oil condition or low oil levels, can lead to hydraulic tensioner sometimes sticking/ not tensioning and the possibility of the chain jumping on the sprocket and the timing going out. You would usually hear the chain rattling and the engine would run poorly if that happened. It can also damage pistons, valves and lead to sudden terminal failure. Low annual mileage examples are affected most apparently....

Edited 5 October, 2014 by xman

[Pappafox]

Hi Xman,

 

Sorry for the drip feeds. Your recap is a good summary.

 

To try and answer the questions.

 

We've had no misfiring at any time.

 

1. The original fault was engine management light on and juddering and partial loss of power - especially uphill.

Mechanic used diagnostic machine and I was with him.

Had error code P16687  cyl 3 misfire. Code resets

 

2. Added a cleaner into the petrol to try and clean any debris build up 

Afterwards  P16687 and P1668 cyl 2 misfire. Codes reset.

 

3. Changed coil packs. All 3 . Same problem. Codes reset.

 

4. Plugs taken out and noted that no 2 very "sooty" black - not oil though.Plugs 1 and 3 seem OK.

Plugs put back.

 

5. Next day compression test No 2 and 3 down . I will try and get these done again as I didn't take accurate readings.

All the spark plugs changed and then noticed the split vacc pipe.  Taped up the split as a temporary measure (until new pipe sourced - only a main dealer part!!). Same issue and codes reset.

 

6.Vacc pipe replaced yesterday and same condition.  Starts Ok. Set off Ok but once climbing a gradient engine light comes on loss of power nearly cuts out. Codes not reset.

 

7. Haven't disconnected the battery at all. Will do that   

8. Remember the sticking throttle thingy as an afterthought but it sound very much related to the main issue 

 

9.Servicing...ah well. Been naughty here . For the first three years it was under Skoda warranty thingy so was serviced ok.

Since then I think the oil has been change just the once. New plugs, air filter oil filter etc changed once maybe 3 years ago.

Same mechanic has done the MOT each year (due 1st week of November)  and  if we needed work doing on it did it. Unfortunately he retired last month and not able to look at the problem now.  

[GeneralPurpose]

Hello Pappafox, sorry to hear you have a problem with this excellent little engine. I've had a read through the thread and some good advice here, particularly the use of vag-com to be sure what's happening. But just a couple of things I'll mention. It's highly likely the problem is due to worn exhaust valve guides. Worn valve guides will always affect compression after a short while as it wears the valve seats unevenly causing all sorts of issues, but importantly, loss of compression. At first many folk don't notice the slight loss of performance, but it gradually get worse until misfiring starts due to poor emissions etc and the engine going into limp. So your mechanic friend is probably right!  Based upon what you are saying, this is almost certainly due to your poor maintenance schedule. Correct me if I'm wrong, but the car has only had 4 oil changes in it's life as an 8 year old car, or there abouts? And the first 3 oil changes were in the first 3 years! That means you have only had 1 oil change in the last near 4 years? You also do low mileage by the look of it, which means if anything you should be changing the oil more often, not less. Oil overdue for change will exponentially wear the valve guides, particularly the exhaust valve guides which become elongated inline with the camshaft rotational plain. This is much like the cylinder bore oval wear that occurs over the life of an engine, again in line with the cranshaft's rotational plain. Of course, every other part of the engine will also suffer exponentially more wear. Sludge reduces oil flow in the valve gear quite often more than other parts of the engine and you won't know it's there until you get a problem. The other issue is that the poor oil quality may have caused sludge to block the piston ring grooves causing one of more of them to stick in their groove/s making that ring less efficient, reducing compression etc. The bores may also be glazed further reducing compression. Poor oil quality does those things. I've seen this repeated on all makes of engine over the years and it can be expensive to fix if you cannot do the work yourself. My advice is the same as some of the guys are saying. Get the vehicle properly vag-com checked to be more sure of the issue. Although to me it's pretty clear if the compression is down on 2 cylinders, it's a strip down. Next, get a good mechanic and in future, be careful not to skimp on oil changes. It's vital not to do that and make sure to use the correct specification oil that has the VW rating for your car. It's the only way to go! I've seen engines with less than 25,000 miles on the clock that are 6 years old with worn out cams due to lack of oil changes once out of warranty. Owners think that because their mileage each year is low, they don't have to change the oil so much!  Wrong, change it more as it's regarded as extreme operating conditions if you do low miles and the engine may not be reaching a nice hot temp each time with the oil fully warming up. Good luck on this and keep us all informed if you can. 

 

PS. sorry if I sound a bit harsh with my comments about the poor frequency of oil changes. It's a point that must be made however, and it's meant as a helpful comment, and not in a critical way. You are not the only one to have fallen foul of an issue like this so don't beat yourself up about it. 

 

PPS. just one other point. To reset your ecu you need to disconnect the battery for at least 31 minutes before reconnection to reset the engine parameters. I'm pretty sure that applies to your year. 

Edited 6 October, 2014 by Estate Man

[Richf]

Oil wouldnt cause this fault , not a chance !

 

This is is not a mechanical fault

[GeneralPurpose]

Hi Richf, I bet it is! But of course, neither of us has seen the car for a diagnosis. And that is really the only way to tell. I'm just basing my assertion on what the op has said and what I've seen in the workshop over the years. And if it's down on compression (granted, we don't have the figs but low enough for the examining tech to make that diagnosis) then that is always a mechanical fault if it's over the manufacturers specs which I suspect this is otherwise the diagnosis of the tech would be different. Interesting issue!

[xman]

I think estateman is probably very right. The low mileage is probably made worse by short journeys where the oil is not allowed to get to full temperature, so contaminates, water and petrol accumulate and sludge forms. And I bet you didnt use the best longlife synthetic oil...

Interesting to hear an explanation of the valve guide elongation, I would call that wear, I understand its ovality, but surely the length of the guide doesnt change.....

As I know myself, valve seating problems rapidly lead to burnt seats which lead to loss of compression and juddering/surging at speed which leads to more damage....

It could be that the seats are too damaged to repair, in which case a new or replacement head would be required. Only a stripdown will tell...

Edited 6 October, 2014 by xman

[GeneralPurpose]

Yes you are right xman! I should not have mentioned the word 'elongated'.  I think I had that word in my head (amongst a whole load of others which I don't understand!!... ) when I started writing because someone else had just used it. I meant to say 'ovalular'. Funny how you can read your own post over and over and not see these mistakes... But yes you hit the nail on the head with the valve seats, mentioning some of the stuff that happens.   

[xman]

As suggested earlier, a proper vagcom/vcds scan is recommended, and pressure figures before proceeding with a stripdown.

 

I would  change the oil and filter, use 5/30W oil to vw spec. to start cleaning the engine of any sludge.

 

Mann filters are the same as skoda original and are cheap from outlets such as gsf. I use dexos2 oil which is a top quality full synthetic meeting all the specs that my local vauxhall dealer (yes) lets me have at trade for £60 for 4x5 litres - enough for over 6 changes....

 

Get quotes from 2 or 3 recommended garages for the work. But beware, the 3 pot engine is designed to be cheap to build in a factory and is not designed to be stripped and rebuilt, Vag says certain operations such as splitting the block to remove the crank cannot be performed successfully. So consider the possibilty of price overrun or even a total failure to repair. A new cylinder head is a distinct possibilty, and it may be difficult/expensive to source.

 

Consider the alternatives,  including replacement engine from an accident vehicle (fabia,polo,ibiza,roomster and others), trading the car in, or scrapping/breaking for parts. After all its an 8 year old car worth around £1500 if it were running well and had a service history but probably less than £1000 in its present state.

 

Do you want to spend several hundred pounds on it?

Edited 6 October, 2014 by xman

[Pappafox]

Hi Estate man, richf and xman,

 

Very comprehensive discussion which I really appreciate. I think you've nailed it estate man

 

Yes, I'm totally at fault here with the oil change. I did use good quality parts on the last service - all those years ago , oil filter, plugs, air filter fuel filter and recommended VAG oil for the motor. 

Even so , yes I should have changed regularly, especially as it doesn't do many miles and yes very short journeys.

Hands up guilty as found m'lord.

 

Very very interesting about the word "elongated". I've had a couple of mechanics use that terminology when saying what the problem was. I've also heard one say ovality. 

I couldn't get my head around the elongation. It conjured up to me the guide getting longer which I just didn't get.  Great to hear the explanation and now I understand.

 

It's in a garage now   VAG specialist -not a main dealer - where they are going to diagnose the problem. The mechanic said without promoting, after explaining the symptoms.....valve guides- exhaust.   I drove it there and at under 3,250 rpm and no engine light came on. Took it over 3,250 rpm just before the garage and hey presto ..limp mode.

 

I have thought of the alternatives. Any idea where to get an engine from an accident vehicle? How much approx. What about recon engine?

I suppose a higher mileage engine that has been regularly serviced would be a good bet?

 

This car has been my better half's and externally it has been looked after. We've had it since new and hasn't cost anything for the last 5 years.

We had had a 1.0L  Polo for 13 years prior to this and it had only done   65,000 miles when we parted. Mindst you though the oil was changed very regularly and i was a lot younger then. Old age - and a company car - makes you lazy..

 

i will keep you all informed on progress. This is one hell of a helpful website !!!  

[GeneralPurpose]

Hello Pappafox, yes a good VW specialist is a move in the right direction. I agree about this site being a good one. Many folk on here know loads and xman probably knows more about the 1.2htp engine than many others as he owned at least one that I know of and works on it himself.  I'm ex-tech but have not professionally been trained to tech on Skoda's so I had to learn quite a bit about my new Skoda when I first bought one. This site and the guys/girls on it were superb in filling me in and bringing me up to speed quickly. Since then I've had a few of them apart including the Vrs and it's VW counterpart. But you tend to find 'specialists' amongst us for particular cars and engines that can always help.You will always be guaranteed a lively debate on most things with lots of help too. Always visit if you have a problem. Do as you say let us know how you are getting on with this. We can all act as eyes and ears if you are trying to locate an engine. But wait until your specialist had taken a look first. It may not be as bad as needing a new engine. Good luck.

[Pappafox]

Eh up estate man,

 

Thanks for your kind words.

 

Will update tomorrow on where we are with the diagnosis and repairs!!

 

Cheers

[Richf]

Cant see how the valve guides are heavily worn on A) A low mileage engine 2) Without allowing oil by becuase there is no oil smoke

 

An oil change is a total waste of money at this point

 

If the compression was that low the car would be very hard to start and would have no power at all

 

But an expert/someone with vag com is essential

Edited 7 October, 2014 by Richf

[GeneralPurpose]

Hi Richf, yeah...I know. But you'd be surprised at just what can happen inside an engine without burning any oil. I've stripped engines with broken rings and it still didn't burn any oil. Some still run actually pretty good too with that broken ring/s. One of the most common causes, amongst other things, of worn valves, seats and guides can be poor oil maintenance. It can be on engines of any mileage or age and even much newer lower mileage than the OP's. But on newer low mile engines it's frequently down to poor oil maintenance where the vehicle is used for low miles, short journeys, like the OP's. Remember too, that in this case the OP's car hasn't had an oil change for years and does low miles so the risk to that engine is considerable in the mechanical department. This is why compression is down on his engine. He may have compression rings seized in the pistons due to poor oil flow through the piston oil ways because they are blocked with congealed oil and muck. Very common in instances like this. The exhaust valve guides wear the fastest as they get hot even on shorter journeys but at the same time are only being fed very poor quality oil, dirty, contaminated, and at a reduced flow rate for sure so they wear exponentially. I've seen the valves seize in the guides quite often blowing the head and quite often the engine too. All caused by the lack of oil flow to the valve gear caused by the contaminates, white mayo build up blocking the oil galleries, and sludge. Hopefully, Pappafox is just in time to save the engine...thus saving some money on a new engine. 

[Richf]

I dont think the wear will be considerable we really arent taking about neglect on any great scale . My Fabia does short trips and low miles and the oil is still clear every year going to service

 

I'm not convinced compression is down , we have yet to see any figures.

 

Worn guides WILL burn oil on start up the oil drips down the guide the settles on the back of the close valve , when the engine is started this burns off.

[GeneralPurpose]

Not changing oil in a car of this type for years and using it for short journeys is about as big as neglect can go regarding a modern engine. It affects every part of the engine. Worn guides don't always cause oil to burn at a level you can see and even measure on these more modern small engines. Emission control is very good at mitigating this these days. Not like the old Cavaliers from yesteryear. Inlet guides tend to show more oil burn than exhaust guides usually as oil is inducted through the guide into the cylinder with the fresh charge. Makes a lovely mess over time. I'm taking the original techies diagnosis as being ok as the description of what he is saying is completely spot on and exactly what many techs see on a regular basis on cars with this history of servicing. If he says compression is down then it's down. But as we both have said we don't know how much by. Worn guides will lead to loss of compression due to the valve seats getting hammered out of shape as the valve tries to continually adopt the wrong seating position. Limp mode will kick in as the revs go up due to emission control having problems with unburned fuel and other sensor readings showing summit is up! But of course, as I said earlier, none of us has seen the car for a diagnosis so we can't be absolutely sure just yet. But the original diagnosis sounds about right. In addition, there may be other stuff going on too. 

Edited 7 October, 2014 by Estate Man

[xman]

I'm inclined to richf's opinion re blue smoke. Wouldn'nt the valve springs etc tend to shut the valve firmly even with minor guide wear? Inlet valve guides would show oily plugs, which this car doesnt.

 

We await the specialist's analysis. I wonder if its possible to use a super duper endoscope to inspect the valve seat in-situ, without having to take the head off?

 

Compression figures are key.

 

Personally I dont understand the limp mode at 3250 rpm - the op must get the error code......I'm sure it'll shed some light on this.

 

As this didnt start until the op changed a few things then its possible the engine has more than one fault - those types of faults are difficult ones to crack..

 

One last thought, tha AZQ engine has 4 valves per cylinder.

Edited 7 October, 2014 by xman

[GeneralPurpose]

Sadly it's unlikely you will be able to see the valve seats enough to make a judgement. Even turning the engine over slowly to position the valves in the open position won't show much. In any event there are other better ways to determine valve guide wear that don't involve stripping the engine. If the guides are worn, the seats will be too. Incidentally, the valve stem seals often mask valve guide oil burning to a large degree as although these wear over time, they stop unwanted oil entering the guide, even when the wear is quite considerable, until they break then the motor smokes much more. 

Edited 7 October, 2014 by Estate Man

[Richf]

Yep a leakdown test would be my next step but I strongly suspect when hooked up to vag com it will become clearer

[xman]

Here a tech doc about the AZQ and other 3 pot petrols..ssp260.....

 

http://www.google.co.uk/url?sa=t&rct=j&q=&esrc=s&source=web&cd=5&cad=rja&uact=8&ved=0CCoQFjAE&url=http%3A%2F%2Fpierro777.free.fr%2FDOCVAG%2FSSP260_The%25201.2Ltr%25203%2520cylinder%2520petrol%2520engines.pdf&ei=2Uw0VOmgGYXiaoL4gfgI&usg=AFQjCNGP96HbBrh0xrV59Rat4RfBLdsOLQ&bvm=bv.76943099,d.d2s

Edited 7 October, 2014 by xman

[Pappafox]

Good stuff everyone,

 

I hope this helps other fabia owners in the future.

 

My engine code is BME. Does that make a difference regarding the tech doc? 

[xman]

Revised/updated version, minor differences I think.

Look at this thread about head replacement..it contains information about the head kits I referred to earlier and how BME engines have this problem....one person got a kit really cheap!

http://www.briskoda.net/forums/topic/220910-fabia-bmd-engine-12-cylinder-head-replacement/

Much ebay stuff also e.g...

http://www.ebay.co.uk/itm/VW-Polo-1-2-6v-12v-AWY-AZQ-BME-Cylinder-head-Engine-Repair-Service-/251649521816?pt=UK_Cars_Parts_Vehicles_Other_Vehicle_Parts_Accessories_ET&hash=item3a977af898

This thread has finally convinced me to stop pushing the boat out on oil changes, which is what I use to do e.g on my sons mk1 fabia (AZQ engine) - he does 18-22k per year, and it was always difficult to find a slot to do the service and usually it went 12k, once 15k, although the interval was 8 or 9 months. It went 120k without problems, when it got handed down to daughter in law who only does 2-3k per year. About 18 months later in new (low mileage) hands, and oil checks neglected I was startled to find it had used a whole litre of oil. I did an oil/filter change and its not used much since in the last year but recently its started getting the random mil light/juddering syndrome, which I've assumed was spark plugs (now @ 40k). But now I'm thinking it could be this head problem. Because of reasons I cant go into, I'm unlikely to get involved beyond recommending scrapping the 10 yr old car if the plugs dont fix it!

Edited 7 October, 2014 by xman

[2ndskoda]

did we ever get confirmation as to the compression readings - I seem to recall that it was reported that the readings were low on cylinders 2 and 3 (?)

 

I suspect head gasket. I do not think that worn valve guides are indicated here as a 'fault'.

[xman]

Even if it's a head gasket, the head has to come off and it will be easy to inspect everything.

 

Have a look at the pictures on the ebay link above and you can easily the valve damage. Seems that AWY/AZQ/BMD/BME engines have an inherrent design or material quality flaw that lead to valve guide wear and damage the seats. The examples prior to 2003 also had the tensioner design flaw!

 

Sadly it seems most of VAG's engines have something seriously wrong in their design, e.g. early 1.4 pd 3 pots with chain driven balancers, early 1.9 pd engines with undersized camlobes, most chain driven designs with their tensioners, and of course the sorry saga of the CAVE engine used in the vrs, to name but a few!! 

 

All seem to be very sensitive to damage through neglecting oil change periods...

 

(Sigh)

Edited 8 October, 2014 by xman

[Fatbloke]

Slightly off topic but could an oily MAP sensor be contributing to any of these problems? I have had to clean the missus' (2010 HTP70 - CGPA engine?) to cure difficult starting and poor running twice in 15k miles.