Hi guys,

 

Car Details

Skoda Octavia, 2006, 2.0 TFSI BWA EA113

 

I know the title may confuse people and it may seem like possible breaking of the engine during the rebuild, but I promise its a bit more confusing and is the reason for my post. I recently remove the engine from my car to do a few bits to it unfortunately due to unforeseeable events I had to put it back together without replacing much except from gaskets that need replacing. I took the engine out teared down the top end so manifolds off, timing belt, pulleys and majority of coolant hoses, overall not many parts came off fuel rail and stuff did come off but that is about it really nothing mechanical except from camshafts came out and went back in.

 

Now upon rebuilding and putting back together with the new gaskets and ensuring torque specs were all triple checked as it was my first engine rebuild, bearing in mind I never removed anything bottom end related including the crankshaft pulley as I couldn't get to it in time, I found that the car started sounded a bit like a lawnmower without a downpipe on it as I just wanted to ensure it ran before chucking it all back together, it kicked up worked fine did this about 4 times turning off and leaving for a few minutes between due to only having water in my coolant system and didn't want to boil it. On my last start up it ran fine revs were hunting a little bit it seemed but hunting downwards not upwards so kept creeping down I thought nothing of it at the time but maybe it has some relevance, now I revved it on this last time and it cut out around 2-3k revs and I left it at that putting it down to probably not having O2 sensors so doesn't know enough about itself to run correct. Bearing in mind throughout this whole thing it smelt like it was running rich again down to the lack of O2 sensors.

 

I have since been unable to start it, it still spins fine nothing hitting like a valve or something and neither chain nor timing belt are snapped so both camshafts spin and from removing the valve cover they seem to return to the correct orientation with both the exhaust and intake valve lobes pointing inwards and are the same distance from the center using my cheapish locking tool could quite possibly be the problem not having the camshafts timed together correctly, I've also found on some attempts it seems to come even closer to starting when I hold the throttle down as if its not getting enough air to kick up, the starter doesn't register any movement on the dash but the engine kicks up to around 500rpm on the dash after a few seconds of cracking and the engine looks like its about to kick into life but just doesn't quite get there now onto my actual question is anyone able to provide any guidance on where to proceed and possible for secondary timing marks on the crank and exhaust camshaft other than the ones on the accessory belt and came gear. Last note it does backfire a little bit and if I stop cranking at the right time it backfires fully and you can hear it originally sounded like a loud metal clang but it keeps doing it every so often with no predictability.

 

Thanks in advance sorry for the long story just wanted to give everyone as much information as possible.

I would have thought that with crankshaft and camshaft sensors if they weren't timed correctly you would have a warning light, arising from implausible signal or similar rather than from sensor failure. You could confirm it's ok mechanically with a compression test.

If you're thinking airflow then maybe start with the MAF and wiring, but I'd expect EML lighting up with sensor codes. Check all the turbo hoses too.

I've found if a modern petrol engined car is started from cold and only run briefly e.g. to reposition on a driveway, that it is a bugger to start next time.

 

My theory being the sensors don't read correctly with the cold and rich exhaust gases left in the exhaust pipe until the engine is cranked sufficiently with no accelerator to purge it.

 

I've had to crank several cars having done the 30 second driveway move for 10+ seconds before the engine would clear itself and start.

 

Just saying, and if you didn't have all the sensors connected when you ran it previously that may be further confusing the electronics.

 

My motto, don't start a modern petrol engined car from cold and switch it off until at least 1 minute run time otherwise you could end up with a non start next time YMMV.

My theory is slightly different:

 

If you get carbon on to the spark plug noses, it is awfully difficult to get a good spark, and therefore get the car re-started.

 

Various things might work in this situation (to be tried with the battery fully charged if possible) . 

 

i) new plugs

ii) an 'easy start' spray

ii) a jump (tow) start

iv) putting the spark plugs under the grill (!), with appropriate care and speed (difficult, particularly the speed bit)

 

These can probably be combined, if necessary.

 

it could also help to crank the engine a little with no spark plugs in, to ensure that you have oil pressure and that the hydraulics are all ready to go. Another thing that might help is to switch the ign on, flatten the throttle, and then try cranking.

 

If it does burst in to life, give it a minute or two of more than 2000 rpm, before switching off, or you might have the same problem again.

 

Good luck!

Ok, I should have offered 'wet with fuel' as an option to 'covered with carbon'.

Everyone is so keen to replace spark plugs these days, probably because garages do it as it's quicker/more profitable than cleaning/gapping what's already fitted.

 

A few seconds over a cigarette lighter is all it takes to dry a soaked plug assuming it's otherwise serviceable.

Thank you for all suggestions guys, sadly it seems I've found the issue in the locating pin on the VVT solenoid sheered off, I'd expect this to be because of my lazyness in both using the bolt to draw the VVT solenoid on and damaging the locating slot and then accompanied by the fact I timed the head off the block so likely was out of time with the block as I forgot to double check the timing of the camshafts after lining up the exhaust camshaft and crankshaft. So my rush to get it together has caused 2 bent intake valves, anybody any suggestions on maybe what I can possibly get away with replacing to get it running on a budget?

 

How likely are the conrods to be bent or valve guides/pistons to be damaged, from what I can see the intake valve shafts appear straight so far so unsure if they've caused damage to the head itself or they've just been bent at the valve end so obviously not sealing correctly.

Sorry about that. They're complicated engines with quite a lot to keep in mind whilst assembling.

 

I've no direct experience only what I've read on timing chain failures. I doubt the controls and pistons are unserviceable. You'll be able to see how much of a whack the piston has got with the head off again!