AUB 1.4 16v Engine Swap Out

[mrdaf]

Good afternoon chaps,

 

I recently bought a Skoda Fabia Comfort very cheaply, with the knowledge I'd have to replace the engine - I've got a fair chunk set aside for it. I would like some advice on the engine types.

 

Firstly, is an AUB an AUB throughout, or are there subtle variations throughout the range, e.g. my current engine is an AUB 6Y2, would an AUB 6N2 replace it easily? (ebay)

 

Secondly, would it be advisable to swap the AUB with a BBZ? What are the implications of this? My AUB has worn piston rings, and I'm sure I read that BBZ's don't suffer so much from this..

 

Cheers in advance!

 

Daf

[mrdaf]

Could really do with advice on this!

[sepulchrave]

An AUB is an AUB, mounts and ancillaries may need swapping from yours but if you buy a bare engine they're the same. 6Y2 is simply the model code for the Fabia Mk 1.

 

A BBZ is incredibly similar, but I can't guarantee you won't have to source brackets/mounts etc. from a breakers to make it fit correctly, also your ECU may get upset.

 

My AUB does not have worn/stuck piston rings, it may be smarter to get your engine rebuilt properly than buy an unknown secondhand unit since they seem to vary so much.

[mrdaf]

I wish I had the time (need the car for 30 mile round trip every day) and money to have someone rebuild it. I'm not an experienced mechanic by any means but I do intend on keeping the old lump though, and getting my hands dirty with it. We'll see.

 

Thank you anywho!

[sepulchrave]

If the car is using a lot of oil (mine did at first as well) you may find that the rings are stuck rather than worn, this happens when the engine is driven too gently using cheap unleaded rather than super which is what the engine needs.

 

You may also be suffering with a blocked engine breather box, this too is common on these engines and it leads to greatly increased oil consumption and reduced performance.

 

You should definitely do a compression and leak-down test to identify which cylinders are affected, you should also see if you can get the bores inspected using an endoscope. Both these options are relatively inexpensive and you may even be able to hire the kit necessary to do it yourself.

 

If the condition of the bores suggests stuck rings rather than wear you may be able to free them off with a process called 'piston soak', once free you then need to thrash the engine ruthlessly to re-bed the rings and get a seal back.

 

These engines also suffer burnt exhaust valves due to excessive leaning, this means taking the head off and getting the valves and seats re-cut, I know mine is suffering with burnt valves to a small degree but like you I use the car all the time and need to buy a scrap head to get reconditioned so I can simply swap the heads over.

[felicia16v]

I "think" the aub and bbz may have different crank sensor reluctor rings so may not work unless that is swapped over, never tried to be honest

[mrdaf]

My engine is using a lot of oil, a litre every 200 miles. The idle is really lumpy starting from cold with dips of 500rpm, and has intermittent power until warm, and will very often stall.

I initially thought it was vacuum hoses, checked all connections from inlet inlet manifold to the brake servo, all were split, but I've insulation taped up and jubilee clipped them, with no difference. Still waiting on Skoda to sort out new ones!

I've had the breather off and thoroughly cleaned, it was rammed full of mayo and nasty bbq sauce. This made very little difference.

I've attempted the egr, but it's mounted on threaded bars and nuts, rather than held on with bolts, so I was unable to take it off without removing other components for access. This is outside of my comfort zone.

I've also had the throttle body off and cleaned.

I've had no lights on the dash, but I've not had a code reader on it so I don't know if there have been any that have been suppressed.

It failed the mot last Monday on emissions because it wouldn't rev consistently, and would probably fail anyway. I've got until the end of the month to sort it.

It runs well when warm. Really well actually. Only smokes after coasting for a bit.

I might try the piston soak anyway, I've got a 400 mile journey round trip next weekend to thrash it on, and it wouldn't do it any harm! Any suggestions on what to use? I've read about MMO and something beginning with a K, but don't know where I can buy it from.

Thanks for the input chaps.

[sepulchrave]

If you haven't changed the coolant temperature sensor, go ahead and get it done right away.

 

Don't forget to reset the ECU by disconnecting the battery afterwards, this will force the ECU to re-learn all settings from the base map.

 

Buy the piston soak stuff from the internet and tell us how you get on with it.

[mrdaf]

What's the reasoning behind the coolant temperature sensor?

[sepulchrave]

What's the reasoning behind the coolant temperature sensor?

 

They don't age well and cause over and under fuelling, your car sounds like it has both issues.

 

Edit: forgot to mention the thermostat, unless your temperature needle sits at exactly halfway once warmed up and it warms up quickly you'll need to change this as well.

Edited 10 November, 2013 by sepulchrave

[mrdaf]

It warms up in about 10-15 minutes, and the needle sits a little colder than half way. I've only noticed it colder than that once.

 

I've purchased the coolant sensor, just waiting now.

 

I still haven't a clue what to use for the piston soak though, and I need to be doing that Thursday night! Had a look in Halfords, they've got a myriad of engine cleaners, but none that I recognize as piston soak oil.

 

My ASR light came on this morning when it was struggling to warm up and approaching stall. It disappeared after I turned the engine off and on again though.

 

I probably should have mentioned I'm using Castrol GTX 15-40 at the moment, and it's on its 2nd full tank of premium fuel since I've had it. And it does 'seem' to be smoking less.

[mrdaf]

Right, where to start..

 

Coolant temp sensor changed, no difference.

Thermostat - attempted a change, wrong part delivered, waiting on replacement.

Didn't manage the piston soak, this is rescheduled for tomorrow evening, with an oil change and a good run on Saturday.

I'm also taking the crankhouse breather pipe out of the intake, and exhausting to atmosphere through a filter.

 

I bought a cheap code reader, and it isn't good. I don't know how the engine management light isn't on.

 

ARS Codes:

00588 - Air Bag Igniter Drivers Side

00532 - Supply Voltage B+ Signal Too Low

01299 - Diagnostic Interface for Data Bus J533: No Communications

 

ABS Codes:

01314 - There are faults

 

Engine Codes:

18020 - ECM Incorrectly Coded

16684, 16685, 16686, 16687, 16688 - Misfires in all Cylinders

16786 - EGR Flow Excessive

17586 - Linear O2 Sensor / Pump Current Open Circuit

17604 - O2 Sensor Heater Circ. Bank 1 - Sensor 1 Electrical Malfunction

17953 - Throttle Valve Controller - Malfunction

 

Looks like I need to get the EGR valve off, and throttle body again.

 

Would it be advisable to delete all codes and see what pops back up again?

 

Cheers.

[sepulchrave]

Right, where to start..

 

Coolant temp sensor changed, no difference.

Thermostat - attempted a change, wrong part delivered, waiting on replacement.

Didn't manage the piston soak, this is rescheduled for tomorrow evening, with an oil change and a good run on Saturday.

I'm also taking the crankhouse breather pipe out of the intake, and exhausting to atmosphere through a filter.

 

I bought a cheap code reader, and it isn't good. I don't know how the engine management light isn't on.

 

ARS Codes:

00588 - Air Bag Igniter Drivers Side

00532 - Supply Voltage B+ Signal Too Low

01299 - Diagnostic Interface for Data Bus J533: No Communications

 

ABS Codes:

01314 - There are faults

 

Engine Codes:

18020 - ECM Incorrectly Coded

16684, 16685, 16686, 16687, 16688 - Misfires in all Cylinders

16786 - EGR Flow Excessive

17586 - Linear O2 Sensor / Pump Current Open Circuit

17604 - O2 Sensor Heater Circ. Bank 1 - Sensor 1 Electrical Malfunction

17953 - Throttle Valve Controller - Malfunction

 

Looks like I need to get the EGR valve off, and throttle body again.

 

Would it be advisable to delete all codes and see what pops back up again?

 

Cheers.

 

Yes, exactly that, some of those codes will be old and irrelevant, many relating to a disconnected or flat battery.

 

You need to recode your engine to 00071 if you have PAS and Aircon like most 1.4 Comfort spec. cars, thats the 18020 code you should do first after clearing all the codes.

[mrdaf]

How would I go about recoding my engine? Do I need to go see a specialist?

 

All codes deleted, and after a short drive they all came back, apart from the ABS code.

[sepulchrave]

How would I go about recoding my engine? Do I need to go see a specialist?

 

All codes deleted, and after a short drive they all came back, apart from the ABS code.

 

You don't need a specialist, just VCDS and a laptop and cable to recode the engine.

 

From the codes you list I would say you have the following problems:

 

EGR valve adaptation needs doing, very common, if dead buy a Pierburg replacement from ebay for about £50

 

Your battery or one of the main earths is in poor condition, check the alternator as well, a brush pack is only £20 if needed.

 

Dying coilpack and probably HT leads and fouled spark plugs, £60 for the whole lot.

 

Oil fouled Lambda sensors, these can be cleaned by soaking them in white vinegar but the front one may have died.

 

Throttle body adaptation needs doing.

[mrdaf]

Blimes, it's been an eventful 9 days.

 

Last weekend:

 

Piston soak 1 - MMO for 16 hours, cylinders 1 and 4 were empty within 3 hours, topped up and left over night. All cylinders were empty at the end, and didn't look any clearer.

 

Changed oil and oil filter - replaced with 5w30

 

Replaced Coil Pack, HT Leads and Spark Plugs.

 

After this session, it started miss-firing when hot (only misfired when cold previously). I've lost engine power (new symptom) and had to pull over on a couple of occasions, each time I've removed spark plugs immediately, with oil smoke coming from cylinder 1.

 

Thursday Night:

 

Cleaned Throttle Body and as far into the intake as I could, replaced gasket ring and replaced. No more throttle valve errors.

 

Took off EGR, with pipe, and cleaned the hell out of it, re-fitted with new gaskets (there weren't any old ones on).

 

New thermostat fitted, up to temperature quicker and gets to midpoint on dial and stays there.

 

Removed front lambda sensor, left to soak in vinegar overnight.

 

Friday Night:

 

Refitted lambda. Got a myriad of o2 sensor codes from that! Bought a new one and fitted it this morning. No more o2 sensor errors.

 

Capped off crankhouse breather connection to throttle and it's now vented to atmosphere through filter.

 

Piston soak 2 - using Seafoam, again cylinders 1 and 4 emptied pretty quick, cylinders 2 and 3 were still full when I checked after 3 hours. Cylinder 2 was still full in the morning. PROGRESS!!

 

After a month of research, 2 weeks of messing around, dismantling, cleaning and bodging, I had my MOT retest yesterday (first one was on the 4th November, failed because the emissions were so dodgy, they couldn't actually perform the test), and it bloody well passed!

 

Whilst I'm over the moon I can keep it going for another year, I am now left with the following DTC's:

 

18020 - ECM Incorrectly Coded

16684 - Random Misfires

16685 - Misfire Cylinder 1

16688 - Misfire Cylinder 4

16786 - EGR Flow Excessive

17756 - Ignition Coil Stage 1 Open Circuit

 

I plan on replacing the EGR valve as suggested, but that can wait until after payday.

 

I'm not too sure on the misfiring. It's a new coil pack (albeit a cheap one), but I think it's because oil is getting into the cylinders and fowling the spark plugs. Although, the Ignition Coil Stage 1 error points to the Ignition pack Ignition Coil Stage 2 Open Circuit came up during the week too, so it might be the coil pack.

 

I bought a Vagcom usb lead from ebay, and ran VCDS-Lite on my laptop. Plugged it in and it picked up all modules bar 01-Engine. So I shan't be purchasing VCDS-Lite and recoding the engine. I don't know what impact this will have, but I can't see any issues that aren't explained by something else.

 

So after all that, I'm not getting a new engine. I'm hoping a few more piston soaks and some longer runs (without ragging it) will do it the world of good! I've noticed the oil level not diminishing so fast, I didn't have to top it up on Saturday morning!

 

sepulchrave, thank you so much for your help, it has been greatly appreciated (you've saved me quite a bit of moola!).

Edited 1 December, 2013 by mrdaf

[sepulchrave]

Cheap coil packs can be DOA on the 12v side which is where the codes come from, they get worse when hot, I've had this happen to me, I had to buy a better quality coilpack.

 

VCDS Lite can be a bit hit and miss when reading the engine ECU with a cheap lead, keep switching the ignition off and retrying, set USB serial port to 9600 baud in VCDS options and persevere.

When it does connect then hit the recode button and enter 00071 and the Do it! button. You don't need to buy the full package to do this.

 

Absolutely DO RAG IT!, thrash it ruthlessly, the piston rings will love it, use ONLY super unleaded, I use Tesco Momentum 99 because it seems to pink the least on it.

 

You're very welcome, there is a massive amount of utter crap written about this engine, most of the problems stem from little old lady first owners who drove it far too gently when new partially glazing the bores and getting the rings gummed up with oily blowby.

[mrdaf]

I'm actually going to put the old coil pack on later, and see if the error goes away. Didn't get any coil pack DTCs with that one.

 

The only reason I'm not ragging it is because of the misfiring issue, so if it works, I'll do my best. As for the fuel, I've been filling up with either Momentum or Shell V-Power since I've had her at home.

 

Edit

 

Just swapped the coil packs over, erased all codes, and then took it for a 4 mile test run.

 

It stuttered a couple of times on cold start, dipped to 300-400 revs for a couple of seconds and tried to stall, but recovered and kept steady. Pulled out of the car park, was a little dodgy still. Pulled out on to the main road, and up the steep hill in 3rd, wincing, waiting for the misfire, I plied the throttle a bit more, 3000 revs, so far so good, got to the top of the hill, turned off down the back roads and let rip.

 

PERFECT! Felt amazing! I don't think it's ever felt that powerful! So bloody happy! I checked the error codes when I got back, only the EGR and ECM code remain. I do think I need to get a proper set of boots for her though, she was all over the place!

Edited 1 December, 2013 by mrdaf

[mrdaf]

Apologies for the double post, but my edit buttons have all disappeared.

 

I managed to recode the engine last night, changing the baud to 9600 worked first time! Happy days.

 

Drove to work this morning, 15 miles of back road fun! Checked for engine for DTCs when I got in, and only the EGR code remains.

[Breezy_Pete]

Much respect to the participants in this thread.  Great to read this sort of problem-solving and persistence.

[mrdaf]

Well for anyone who's interested, I've have more issues and have done a lot more work on the little beast.

 

The oil burning issue didn't go away, I was going through about 5 litres every 400 miles, which is just ridiculous. I've been offering free labour to my local garage on a Saturday since February (part of my future career plans) and they've been uber helpful.

 

In April, I took a week off normal work, and took my car into the garage with the intention of sorting out the issues! I started off with a compression test, which every single cylinder failed on. Can't remember the readings but it wasn't good either way.

 

I took the engine apart, leaving the cylinder body and crank assembly in the engine bay. Took the pistons out, which wasn't any trouble at all. The bores were glazed with a mirror finish, and the rings weren't providing much of a seal. The rings were replaced, and the bores deglazed.

 

I had the cylinder head out, and removed the valves, the stem seals were shot, and only one seal still having the tension spring on it. The valves were filthy, coked up with 10mm thick in parts. I cleaned each one by hand, back to bare shine. They looked beautiful when I'd finished. After degreasing and cleaning the head, I lapped the valves back in, what a bloody tedious job! Spent several hours doing that. Put the clean valves back in with new stem seals, and water tested the valve beds. All good.

 

I put a new head gasket on, and put it all back together with a new cam belt kit and water pump. New inlet manifold and exhaust manifold gaskets, cleaned the crankhouse breather again and put in new o-rings, and put in a new EGR valve.

 

This took 4 days, whilst helping out with other jobs in the garage, and I eventually got it all going on the Thursday evening. Started first time! Absolutely chuffed to bits. Left it at the garage on the Friday idling all day, letting everything bed in before taking it out on the road.

 

Since then, I did the whole 1000 miles taking it easy and running it in, before a full service. During the service, I noticed a lot of oil seeping from the head gasket, and down the engine block. I spoke to the chaps at the garage, and suggested I check the head bolts. The instructions for the head bolts seemed a bit weak when I initially did them up, but I double checked and left them as instructed. So I checked the head bolts, and whilst not loose, they comfortably turned another 45*. Since then, leakage has been minimal.

 

This evening, I finally got around to fixing my aircon. Quite a common problem with the aircon wire breaking off at the plug, located towards the front of the engine in the middle, right next to the alternator plug. I tried saving the plug, but made a mess of it, I ended up lopping the plugs off and wiring them together using crimps, and protecting them with a lot of insulation tape! All good.

 

Only a wheel bearing to sort out, when it gets too loud to put up with..

 

If anyone has any questions, fire away, I'd be happy to share my experiences with this wonder of a car!

[TMB]

Well done, mrdaf. I'm loving the quality and thoroughness of your work!

[sepulchrave]

The only comment I have is that in order to bed the new rings in you need to thrash the engine up and down the gears, not let it idle and get glazed up again!

 

When we dyno a fresh engine, we generally only fast idle for 20-30 mins it to run cams and followers in, this is the only metal to metal contact other than the rings themselves, if the engine has just had a re-ring and glaze bust we give it death once it's at operating temperature, it's good for the ring seal to work it hard.

[mrdaf]

That is a fair point, but I took the advice of the gaffer at the garage. I have been putting it through it's paces though, with a few 200+ mile journeys and aggressive back road driving. I've not checked the cylinders or compression since, but I have kept a very close eye on oil levels that don't seem to be going anywhere. I'm happy with the work I've done, and even happier with the car's performance since.