Wideband lambda on 1.2 12v AZQ (EGR valve in the end)

[Breezy_Pete]

So we've had our Fabia a couple of months now, and it's been very little trouble so far.

Log of fuel consumption over the first 5 or 6 fills gives an overall average of around 38/39mpg (brim tank - miles done method), which seems a little low to me. Mixed driving, more urban than not though,so maybe it's typical.

It does occasionally suffer from stuttering/stalling as you go to pull away from a standstill, which has been improved

by a dose of fuel system cleaner, and I think further by a throttle body clean. (Looked great from above, vile from below!)

No fault lights on, but we haven't scanned it with anything so there may be info stored I guess?

Sparkplugs/oil/oil filter/air filter are all new or very recent. Have a replacement fuel filter but have yet to fit. Coolant temp sensor seems to have the right resistance at ambient.

It does seem to tick over very smoothly, and pull fine once the revs are up a bit, I'm not convinced it's 100% right though,

and I need to know that it is running at its best.

Ideas I have, please comment :

1. Get a scan done, preferably by a knowledgable amateur. Or invest in the kit myself.

2. Do a compression test, as I've read scary things on here about valve/seat problems, and this engine's done damn nearly 100k. Haynes seems to suggest that because I'd need to unplug coilpacks and injectors to do this, it would need fault codes erasing afterwards. Any sneaky ways round this? Would the fault light(s) go out on its own after a while?

3. Test the pre-cat lambda and replace if faulty or below spec. The service book seems to ask on every page whether this got changed during the service, so Skoda are perhaps not sure on lifetime. BTW, can anyone confirm for me that the part number fitted to the ('05 reg, AZQ eng code) car will be 03E906262? (or tell me where on the sensor/cable to look for the number?).

My local VAG parts man says this number has been superceded now, anyone know why?

I've seen a description of how to test the wideband probe with a VCDS type thing, but I'm not sure whether this would identify a sensor as being just a bit 'old and tired' as opposed to really stuffed, which would surely put a light on the dash.

Has anyone here changed one of these on an AZQ?

Anything else I can look at or clean/test? Could EGR valve be relevant?

Thanks for reading, if you got this far.

[awfabia]

Like all engine faults you need to ensure that all the 'basics' like plugs, air filter etc HAVE been done or you may spend a lot of time looking for a complicated answer to a simple problem.

Taking the coil packs off shouldn't cause 'fault code light' to come on, you could therefore check compressions. My son's Fabia 1 with the 3 cylinder 1.2 engine has done 100,000 trouble free miles which, I believe, is common. A great little engine.

You will find all you need to know on this forum about scan tools and VCDS type things.

I bought a 'Gendan' scan tool for £60 which seems to do most things but e.mail them and ask if it will do what you need - they're very prompt to reply.

www,gendan.co.uk

Also, I'm sure someone will be along later to give advice on your problem.

[Breezy_Pete]

Thanks for this, awfabia.

I didn't trust the (indy) dealer we got it from particularly, especially after discovering what was undoubtedly the original factory-fit pollen filter still in place, so I did eyeball all the service items that were claimed 'done'. I think they all had been.

The plugs looked like this:

Pretty new-looking I think, if sooty around the ends of the threaded bits. Anyone think these look abnormal in any way?

Thanks for the advice about coilpacks, I guess if I insert the plugs back up them and earth each ground electrode they'll still spark away happily and the ECU will be none the wiser that they aren't in their usual places. Worth trying to avoid the injectors injecting during comp test or not worry?

Thanks also for the encouraging words about the reliability of these engines.

I thought of a 4th thing to check, the cam chain timing. I think I can just remove some covers where some locking pins go and do this visually? Flywheel one may be awkward to see??

I'll have a look at Gendan stuff, ta.

[skodafan1]

Basic Timing Check

- - - - - - - - - - - - - -

You can test the basic timing health without the special locking tools. Simply open the two cam end covers on the engine flywheel end. You will need a 10mm spanner and a knife to prise out the plugs. Once removed use a mirror and a lamp to inspect the cam end slots. The slots should be aligned with one another i.e. 6 o'clock, 10 to 4 etc. If they are not aligned (as in my case) then the timing chain has jumped.

If you still have doubts then go ahead and buy the special tools (typically about £40+). With the locking tools you'll have a bit of "fun" locating the locking pin into the crank sensor aperture (to be found at flywheel end under the inlet manifold)!

I agree with the other poster, the Gendan tool is really useful. Timing issues can be flagged up as MAP sensor improbable signals.

Prior to the chain replacement my plugs looked as dirty as yours.

Finally, pollen filters. My old Octavia and current Fabia had full service history's and came complete with the original filthy pollen filters! Fortunately, ECP can provide you a new pollen filter for £5.99.

Let us all know how you get on. Best of luck.

Simon

[Phil-E]

Hard to tell properly from the picture but the ends look a little white (running lean?). They are pretty mucky on the thread too.

I too replaced my cabin filter recently and think it must have been the original. There were a LOT of leaves in it and it was dark black. I think it gets overlooked quite often!

Phil

[Breezy_Pete]

So the weather finally improved enough to let me make some progress on this.

Got a cheap handheld Gendan code reader which came up with only an EGR fault, 17811 - "Control Difference"

I thought this might be down to the valve being clogged up with carbon?

Got some gaskets (2x 036131547F) and decided to remove the EGR valve for inspection, as the inlet mani end of the pipe had been pretty grotty when I was cleaning the TB. The two nuts that held it in place were rusty as hell. Even thoroughly PlusGas'd in-situ I soon gave up. I had that "something's going to break" sensation.

So I decided to remove the adaptor block from the head, and disconnect the pipe from the inlet manifold, and remove the lot.

Interestingly, slight evidence of leakage from the coreplug in the bottom, but it seemed pretty secure still.

I've seen the pdf that's kicking about showing these valves failing dramatically at that plug.

Even off the car, those two nuts put up a struggle, but I won in the end.

Got a new gasket for adaptor-block to head (036131547G) and two new 'shouldered nuts', N02300313 for re-assembly. They are the 'pinched' type nuts like exhaust manifold ones, but with a grey rather than coppery appearance.

The internals of it were really very clean. Just the lightest dusting of carbon and the valve itself seemed to move freely enough. The metal pipe round to the inlet was also really clean internally, all except the very last bit that sits inside the inlet mani. I guess the valve itself runs hot enough to be self cleaning.

Haven't cleared the code yet, but I don't really think anything I've done is going to have solved whatever the issue was. At least I know I can get it off easily now with its new nuts if it does need more looking at or replacement.

Then I moved on to timing chain check and compression test.

All good here.

I didn't 'pin' the flywheel at TDC with a locking tool (too pricey, too hard to fit), just stuck a long allen key down no.1 sparkplug hole, and used some improvised bits to prove the camshafts were in phase with crank and each other:

Yay!

Compression test (fully warm) gave 16 bar for No.1, 15 bar for the other two cylinders. High!

I don't really have a theory about why there's a difference, but it was repeatable.??

So, all in all, pretty encouraging I think, and the latest fill-up yielding 42.7 mpg pushes

the 'since she's owned it' average to 39.9. Maybe that's as good as it gets?

I'll update again when I've cleared the 17811 and given it a while to see if it returns.

[Avalon]

I don't trust anyone when it comes to my car, it's safer that way. Like you I had a cabin filter and fuel filter that hadn't been changed in at least 6 years and an independent who admitted not changing the fluid for 6 years when I got it.

The compression test is promising, I suspect part of your problem is the type of driving (urban) combined with shorter journeys and the temps we've had till recently. I'd suggest an italian tune up and a tank or two of (more) expensive fuel (ideally from Shell). Before someone points out the supermarket stuff comes from the same tanks at the refinery, it does, but the detergent package added to it is delivered based on the swipe card used by the tanker driver and this is the difference, vpower is tanked from a separate source afaik.

[rum4mo]

I fully agree with Avalon's statement on petrol.

EGR system, well that is the condition that I found the EGR valve on my wife's 1.4 16V Polo, any crap will end up being on the lower end of the TB and the inlet manifold near this point, looked to me that scavenged crankcase fumes and exhaust gasses being passed by the EGR valve merge and make a gummy mess where the EGR pipe enters the TB or manifold - maybe check that area for choked aperture(s). One thing you might do is, record the EGR valve "end stops voltages" and perform adaption, then see what the new "end stops voltages" are - in my case, the lower end voltage had increased quite a bit - and with that in mind I am going to fit a new EGR valve as there is still a hint of "fluffy running" when "off load". It could be that the end stop voltages change due to ageing of the positional sensor - or the solenoid is now not moving through its intended range fully.

[rum4mo]

Seeing as I can't "edit and post"!

I was going to add that I would not expect to see any sign of leakage at that core plug - as you don't know what its effect might be at different stages of the solenoid opening, or fully closed.

[Breezy_Pete]

Gents, thanks for these comments.

Liking the idea of the Italian tune-up; next weekend should present some opportunities. I'll treat the car to some posh petrol too.

Must get round to changing that fuel filter too.

I really don't know enough about this EGR valve, and how it works with the ECU. This is the scary pdf: http://www.ms-motor-service.com/ximages/pg_si_0084_en_web.pdf which seems to suggest that Pierburg have had 3 goes at it, with 07.0, 12.0 and 16.0 at the end of the part numbers, mine being an 07. The ECU version seems OK though, pretty sure I saw 5329 on the outside of the 'tin'.

Seen reference to a potentiometer (G212), inside the EGR, presumably for valve position feedback, but I couldn't work out what was going on with my multimeter. Putting volts between pins 1 and 5 made the solenoid bit clack and the valve open, but I couldn't measure what I'm used to measuring for a potentiometer amongst the other 3 pins (with no volts on anything). Is it an active digital pot or something fancy?

Think I need to borrow someone with VCDS and the knowledge to apply it.

I didn't actually measure it, but it looked to my eye as if the core plug and the hole it's plugging are oval rather than circular. They surely can't have started life like that?! Might explain why there's a slight leak, if everything has shape-shifted. :wonder:

By eye at room temperature, there aren't any gaps that would let gas in/out, but that may change at a few hundred degrees.

I expect a new one may have to go on at some point.

Can someone explain the 'vac' hose that comes from the clean side of the air filter down to this valve. Seems to allow a bit of fresh air to be pulled through at all times, towards the inlet. Extra oxygen for 'afterburning' to keep it clean? Or cooling? Or I don't have a clue? :think:

Lots to learn, all assistance gratefully received. :sun:

Pete

[Phil-E]

Couldn't agree more with the italian tune-up! A car needs a good run from time to time and it certainly won't hurt it planting your foot to the floor a few times and letting it near the red line. Should blast some crap out!

Have you cleared the code yet?

Sounds all very positive anyway.

Phil

[Breezy_Pete]

Cleared the code now. To my slight surprise, there weren't any additional codes before I did the erase. Haynes's description of compression test led me to believe that disconnecting injectors and pencil coils for the test would log fault codes that would need clearing afterwards. Didn't happen.

The 17811 didn't return immediately after running the engine and driving it 10 yards, but I guess the EGR would have to be actually asked to do something before this would happen.

Sudden change of priorities now. Nipped round checking tyre pressures after the code stuff. Pressures were grand, but...couple of spots of black grease on the OSF arch liner; bugger!

Wheel off, CV boot split at a point just outboard of the inner metal band.

While I was there I thought I'd stick a micrometer across the brake disc. 16.8mm.

Haynes reckons 19.0mm minimum. That's another original factory-fit component I've just found then.

I'll do the discs and pads myself, but never done any CV stuff; so what would the 'book' time be on an outer CV boot please anyone?

Ta for reading.

[Breezy_Pete]

I know I should be patient and just get home (where the car is) this evening, take off a front wheel and measure...

...but searching around on here it seems like the front discs might actually be 239s not the 256s that Haynes reckons for an AZQ-code. That would explain the thinness (New 18, minimum 16mm) and make the disc replacement much less urgent. Wish I'd put a ruler across the disc diameter last night!

So do some/all 1.2 12Vs have 239 discs? Any way to tell by the VIN number or info on that page of the owners handbook/service book? (Think I've got a scan of that).

[skodafan1]

I have a 2003 AZQ Classic and it has 256mm diameter discs as per Haynes manual, I still measured them to be certain before ordering replacements.

On the outer CV boot fix, I changed one on an Octavia in a 2-3 hours. Looking at the Haynes manual the Fabia ones look very similar. Simply remove the hub bolt, the three bolts on the bottom of the ball joint and finally the multi-splined bolts at the gearbox final drive end. Preparation is the key, having the right 12 point socket, spline tools and nail pliers/proper tool for the tightening metal bands all helps. I used a JR stretch CV boot (with cone) as I didn't fancy braying the CV joint apart in a vice. I am sure the forum members will have an opinion on pros and cons on the right CV boots!

[Breezy_Pete]

_{Thanks skodafan1, I've just sent off an inquiry to a dealership with my VIN, so hopefully they'll be able to tell me about the disc diameter so I can get on and order if necessary.}

_{I've wimped out on the CV front (have none of the tools nor experience for this job) so have delegated to my local VW-specialist independent, tomorrow afternooon. He reckoned 1.5 hrs.}

_{Edit: 239 discs now confirmed.}

_{Dunno what happened to the font size here!}

[Breezy_Pete]

Well, progress at last on this one.

It's all ended up a bit off-topic relative to the title, but hey-ho.

Now have a set of nice genuine (239!) brake discs and set of pads cheapish courtesy of Ebay/walkerboy. All ready to fit, but no longer urgent.

I've also got a spare Bosch pre-cat lambda now just in case, but I suspect that the issue was EGR all along.

Happily a fella that works nextdoor to my workplace has just acquired the £260-ish VCDS system, and was eager to try it out on cars other than his Audi, so we/he confirmed the fault codes that my Gendan machine was reading, and ran an 'actuator test'. Fuel pump relay and pump itself, + purge valve all did their thing, but the EGR valve was remarkably silent/still.

That gave me enough confirmation to order a new'un, which I got today and fitted. I checked the new one first to see whether I could blow/suck down the air/vac pipe stub (no) which was reassuringly different to the old one, and also did some electrical measurements to compare with the old one when I get round to it. Core plug in the base of the new valve looked nice and round as expected. [Edit: Oh, and despite ECP's website saying that the valve came without gaskets, I later found a little bag mixed in amongst the packaging at the bottom of the box, with two nice new gaskets in.]

I took the old one off, nice and easy second time around, and I bargained on the fortnight-old new gaskets and nuts being re-usable. I put a Vernier across that core-plug in the bottom of the old valve and confirmed what my eyes had told me the other week, out-of-round by nearly 1mm!

No wonder it was having trouble closing off properly, the whole thing seems to have 'morphed'. Wish I'd tried that measurement the first time I saw it.

New one (Pierburg 7.22785.16.0 via ECP) went on easy enough, which I can do a 'how-to' about in due course if anyone is interested?

Now I haven't done any adaptation, but it seemed to run better straight away, idling sweetly at start-up. A quick test-drive round the block suggests a much perkier/chirpier/happier little engine. :love:

So: if you've read this far, I have some diagnostic tips for you . If you find that you can blow/suck and make air move through the little pipe that connects EGR to airbox when engine/ignition is off - be suspicious of the valve. If you have fault codes too relating to it, remove it from the engine (by the Allen-key-head bolts holding the whole shebang to the head if the 13mm nuts seem too hard in-situ). Then have a look at the base of the thing, at that core plug. If it looks sooty round it, and the plug measures different dimensions in different directions, it's almost certainly 'toast'.

[rum4mo]

I disagree with your comments about that fresh air pipe, I have replaced my EGR - though original was okayish, and both allow air through the EGR valve if you blow hard on that pipe, that was one of the tests I did do. I'd reckon your problems could have been due to a distorted EGR body probably caused by exhaust gasses getting out via that sealing plug.

[Breezy_Pete]

Interesting.

I do know a bit more about these valves than when I wrote that last bit, but I'm surprised at your observation. For clarity, did you find that you could blow through old and new valves' little 'filtered air' pipes equally easily? Or are you saying that you could get some air down that pipe on both? I couldn't hear a whisper through my new'un, where the old one was quite easy to move air through.

What failed on your valve? Was it the same Pierburg part number?

I started a thread about that air pipe in the Ask a Tech section which you may/may not be able to see, and it seems to me that it's about keeping the valve guide/stem of the EGR valve clean by making sure that any air leakage around the stem into the main gas passages of the valve is clean filtered air.

My impression is that the easier it is to blow down that little rubber hose, the more wear that indicates on the valve stem/guide, and so the more likely the valve is to stick in a non-shut position due to misalignment/stem waggle, maybe aided and abetted by the main casting having distorted at the valve seat area.

I'll try to do a little sketch later, or at least copy a pic or two from the other thread onto here.

[rum4mo]

One that was removed was the older "R" - version that probably refers to the VAG p/n, the replacement was the later one with the "plastic" packaging on the coil area. Both fresh air points seemed the same resistance wise - I did not expect that. I was only changing the EGR valve to try to get rid of a bit of pinking so suspected that either extra air was passing through this valve or bleed through from this small pipe. I did buy it as an unused spare part at a good price, so jumped in and bought it quickly just in case I needed it - but in reality I was only fitting it to get it out of the way (wife was complaining!), and to maybe improve things wrt to light pinking - MAP sensor replacing with used one next - or cleaning old one.

I did not see that posting, used to be "freedom" but not now.

I was surprised to see that other thread you started only refered to the 1.2 engines - but maybe these engines had rubbish/bad ECU s/w originally and that was stuffing these EGRs on that engine.

Edited 11 July, 2012 by rum4mo

[Breezy_Pete]

The Pierburg pdf, understandably, suggests that the temperature which the valve was exposed to with some ECU firmware versions was beyond what it was designed to take. It seems to me that even with version 5329 like mine, the original revision (suffix .07) of the valve couldn't quite cope, as judged by the shape-shifting of the alloy casting that I found on the original.

This piccy from the Tech thread shows the business end of the valve from below after removal of the 'oval' coreplug, with signs of wear on the stem. The high (exhaust connected) and low-pressure (inlet connected) sides of the valve head are marked up.

The fresh air connection seems only to let a teeny flow of clean air come down between the valve guide and valve stem, (In the direction - out of screen/towards viewer).

I think it is there purely because *some* air is bound to leak down there especially when the inlet mani is at a deep vacuum like at idle, so it must be clean filtered air to prevent 'atmospheric grot' getting into that clearance and accelerating the wear process. On the other hand it may be more about keeping exhaust gases/soot from coming up the valve stem the other way, when the valve is open/working, by providing a little 'breeze' the other way. Probably both.

[rum4mo]

Seems like I can not open that picture as I'm at work, but I've found your posting that it came from, so I'll look at that when I get home. Strangely, on some engines, this pipe just gets terminated in a crude "filter" to avoid stones/grit getting drawn in - not like on your engine where it gets sensibly connected to filtered air.

[tvines]

The Pierburg pdf, understandably, suggests that the temperature which the valve was exposed to with some ECU firmware versions was beyond what it was designed to take. It seems to me that even with version 5329 like mine, the original revision (suffix .07) of the valve couldn't quite cope, as judged by the shape-shifting of the alloy casting that I found on the original.

This piccy from the Tech thread shows the business end of the valve from below after removal of the 'oval' coreplug, with signs of wear on the stem. The high (exhaust connected) and low-pressure (inlet connected) sides of the valve head are marked up.

The fresh air connection seems only to let a teeny flow of clean air come down between the valve guide and valve stem, (In the direction - out of screen/towards viewer).

I think it is there purely because *some* air is bound to leak down there especially when the inlet mani is at a deep vacuum like at idle, so it must be clean filtered air to prevent 'atmospheric grot' getting into that clearance and accelerating the wear process. On the other hand it may be more about keeping exhaust gases/soot from coming up the valve stem the other way, when the valve is open/working, by providing a little 'breeze' the other way. Probably both.

Wow! I am so much wiser now having read all of this. Decided I would reply to you on this thread instead of the "EGR ISSUE" thread; much more informative and on topic.

Looking at your picture above seems to suggest that cleaning this head in a manner like grinding in a valve might remove this coking and provide a better seat and thereby creating a better seal. Is it possible to wrap a piece of string around the stem of this piston to create a clockwise, anticlockwise motion as you would grinding in a valve or am I wasting my time; would your advice be to buy a new valve. And yes, according to an OBD scan, it returns a faulty EGR code, hence my reason for persuing a solution to the problem.

[Breezy_Pete]

What fault code number are you seeing, and are there any drivability symptoms?

And whereabouts in the country are you?

I think your best course of action is to get to someone who has VCDS, and do the 'actuator test' that cycles the fuel pump relay, purge valve and EGR, while listening/feeling for the appropriate clicking at each. That was the clincher for me, when it failed to move/click (the second time we ran the test IIRC), while FP relay and purge valve were behaving themselves, that demonstrated that the valve was sticking, and because of the drivability problem, I guessed probably in a fairly wide open state.

Pulling a significant amount of exhaust gas into the inlet without the ECU's consent or knowledge is surely going to stuff up the fuelling calculation and generally get the things knickers in a right knot.

I doubt whether a small amount of leakage of exhaust gases past an imperfectly sealing valve would be enough to cause any problem; I think that would need a valve that's properly open when the ECU thinks it's closed, or vice versa. So I doubt that it's worth pursuing a valve re-grinding strategy.

The valves ain't cheap though, so do all you can to be sure before you pay out any cash on a new one.

[rum4mo]

tvines, from what I've seen on these petrol engine EGR valves, I reckon that all you could/should do wrt to cleaning, would be use something strong on it - and it seems that maybe oven cleaner is up to that task. Lifting that valve up off its seat might be possible - I have not tried yet as I was worried that I might have damaged the only EGR valve that I had and in doing so make things worse. Now, if you think that you have problems with this valve, and these problems include the valve sticking, then cleaning it up might work but will increase the clearance and if like the OP your valve body is worn, then you will get more fresh air getting past this valve when it is closed. But if you don't try etc etc, I've forgotten what your original problem was, so I'll reiterate - clean the TB/manifold pipe ports as they might be choked

Oh, and after reading Wino's response to your last posting, remember to buy only Pierburg or VAG (they only supply reboxed Pierburg) valves as it seems that there are many pattern parts around.

On the subject of fault finding with VCDS, you can check the current saved voltage values - ie low end, high end and current position, then ask it to operate and see if it can still move to roughly the same positions - if not then it has got sticky/stuck for some reason.

Edited 11 July, 2012 by rum4mo

[rum4mo]

Wino, my EGR p/n will be slightly different to your one as my original one was a "06" which equates to a VAG p/n ending "R" which I replaced with a "T" like your one an evolution of the original item for ???? reason, strangely Pierburg have changed from a slim metal covering to a fat plastic covering for the coil.

Edited 11 July, 2012 by rum4mo