Lumpy fast idle following misfire.

[philhoward]

The "lumpy idle" isn't helped by the first 45 seconds of running where the ignition is retarded and with a rich mixture to get the cat "lit" as quick as possible.  If one of the plugs/compressions isn't totally up to scratch, then it will be amplified and running on 3 (maybe 3.5) cylinders only at startup.

 

When they DO run on 3 cylinders, it's rough.  Very rough.  A 1.2 3-pot Greenline will seem Rolls Royce smooth by comparison.

[Jabozuma]

In the early days of the CAVE engine (might have affected the very first Fabias) there was a batch of suspect injectors - any issues with a misfire on a twincharger and they were changed without question (my early 2010 Scirocco had them changed). When they were still trying to find the problem on the Scirocco, I was getting a set of 4 plugs changed each time (about every 1000 miles at best - sometimes 100 miles) by VW, under warranty. Problem then was the VAG computer calling the wrong plugs off at service time (started playing up after the 38k service), but they never replaced just one plug.

My valve issue - but it was complete instant loss of compression on one cylinder:

Wow, no wonder you had no compression, that left intake valve is eaten away!! Bad combustion leading to deposits which overheat in turn burning the valve off

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[MattGreen]

The 3 pot (canal boat engine) tick over is smoother than my vrs was before it returned to the garage.

[Rooted]

Personally i think 97, 98, 99, 100 or 102 ron fuel is very good in a 1.4 TSI Twincharger with Full Synthetic 5w 30 or 5w 40 oil.

A good Set of Spark Plugs and Air Filter, and VW's latest Maps, be that on a CAVE,

or as the CTHE has as of 2012

 

I just am not prepared to use 'Shell V-Power Nitro 99,  with its Secret Additives, Cleaners-Detergents.

 

Many like it and prefer it, & say the car runs best on it,

but i just feel there are issues with it in a Twincharger.    

Just my Opinion.

 

george

[philhoward]

Wow, no wonder you had no compression, that left intake valve is eaten away!! Bad combustion leading to deposits which overheat in turn burning the valve off

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You looking at your phone upside down?  It's the RH exhaust that was the problem..

 

Ran almost exclusively on Momentum99 and 95% of its miles were cruising at motorway speeds.  Maybe the occasional blat would have helped, but hey..

Edited 19 June, 2014 by philhoward

[Rooted]

Thankfully there have been ECU updates since that engine you had gave up the ghost.

 

Sadly not all engines/cars from that period have had a ECU Update where some needed it.

Sometimes,the Service Desk or Technician says there is not one, or it has the latest.

 

1.4 TSI Twincharger CAVE owners, maybe those buying a used vRS need to check that 

everything is up to date on the car, Latest Map etc, Plugs checked if there is not a smooth start up 

with the engine at 1,100 rpm, dropping to 800 rpm.

 

You never know what Fuel previous owners have been running,

or if someone had the likes of a REVO Remap on it.

That can be a cause of rough idle and misfires.

 

george

[Jabozuma]

You looking at your phone upside down? It's the RH exhaust that was the problem..

Ran almost exclusively on Momentum99 and 95% of its miles were cruising at motorway speeds. Maybe the occasional blat would have helped, but hey..

Err, as the photo is posted, two bigger exhaust valves on top and two smaller intake valves at the bottom. The bottom right intake valve (as I see it) is destroyed. If they changed exhaust valve (s) and left that intake valve in...

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[philhoward]

The Scirocco was the 160PS version and there was an ECU update (late 2011 or so?) to the map - less performance below 4500rpm from memory.  At the time my Scirocco engine went, there were only 2 twincharger cars that had hit 40k (mine being one) and both needed extensive engine work just after the plugs were fitted (hence the problem hadn't been discovered).  Another owner bought a used one with 20k on the clock that the VW dealer had been kind and given it the 40k service as part of the deal.  He had a new engine 400 miles afterwards.

 

Jabo - I always though the inlet valves were the larger valves?  I was under the impression the injector (top of the pic) was on the inlet side as well?

 

EDIT:  It had a new crate engine anyway..but that base unit might have been reconned and resupplied to somewhere else..

Edited 19 June, 2014 by philhoward

[Jabozuma]

Sorry mate, had a senior moment - goes to show posting during boring meetings doesn't work!

EDIT: pretty obvious as intakes are always the ones more coked as they run cooler than exhaust - again, sorry for misleading!

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Edited 19 June, 2014 by Jabozuma

[MattGreen]

So does anyone know what the most likely cause for poor compression is likely to be? Valves or rings? Also any idea what the likely action taken by skoda will be?

[philhoward]

Probably piston based rather than valves - as the pic shows, they burn out pretty quickly!  I was cruising along at 120kph (75mph) and it went in an instant.  Ring/piston leaks can creep up almost unnoticed and decline gradually.

[MattGreen]

Thanks

[Rooted]

And their compression tests can be rubbish. Sometimes totally wrong on a cold engine. Later found to be all correct. Why some engines get a using oil incident never to have one again. The pistols. Rings. Cylinders benefit from the talkative up. But if there is wear then it will be a replacement engine. No rebuilds or short units.

[Rooted]

That was not. Talkative up. Italian tune up. Doh

[Rooted]

Beware of a sticky ring. That is general advice not just skoda related.

[Jabozuma]

Head gasket failure, oil turning to water and blow down into crank case are another two. When valves bur out like on that photo there is no compression whatsoever i.e. cylinder does not hold it at all and compression gauge shows very low numbers. Piston rings failure gives higher readings, still not normal. Piston rings as such do not fail, they are the toughest material apart from valves in the combustion chamber. Ring seats failure and bore glaze/scoring will let the pressure past the rings.

Valve seating and sealing during strokes is the area where the most power can be gained from an engine. Then proper bore hatching and good rings bedding-in procedure. You do not want all that lovely combustion pressure escaping anywhere before exhaust valves open:) racing motors hold compression so well it is difficult to turn them. F1 engines seized when cold and can only be run when operating temps fluids are circulated across the engine first. 

None of the above helps when VAG approved engine oil turns to water above 100C !

[MattGreen]

Thanks for the replies,very helful. As it happens I know quite a bit about engine internals just not so clued up on likely failure modes for the tsi and how Skoda are likely to deal with them.

I believe the main reason f1 engines are seized when cold is the crank/conrod bearing tolerances, they're designed to have minimal clearance when at operating temperature. We used to gap formula ford piston rings to give minimal friction in the bore so they'd just be a flush fit when hot.

[Jabozuma]

Were you a mechanic for FF Team?

[MattGreen]

I spannered a formal ford for a season (at uni-degree in motorsports engineering) and also worked building formula ford engines for a spell.

[Jabozuma]

Cool! What is your take then on twinchargers thirst for oil?

[vxh26]

<snip> VAG approved engine oil turns to water above 100C!

I am assuming this is a wee bit of an exaggeration but is it a reference to failure with Castrol Edge 5W-30 FST (Fluid Strength Technology) oil?

 

I would have thought that oil temperatures of 100ºC were not altogether unusual.  Is the vRS twincharger oil consumption problem down to the recommended oil rather than any particular failing on the part of the engine?  Could it be avoided by using some other oil and if so, what oil?

[Jabozuma]

I am assuming this is a wee bit of an exaggeration but is it a reference to failure with Castrol Edge 5W-30 FST (Fluid Strength Technology) oil?

 

I would have thought that oil temperatures of 100ºC were not altogether unusual.  Is the vRS twincharger oil consumption problem down to the recommended oil rather than any particular failing on the part of the engine?  Could it be avoided by using some other oil and if so, what oil?

Interesting questions! Castrol Edge 5W-30 FST Professionall III (one with yellow black light reactive dye) as used by Skoda is not suitable for high temperatures and loads twincharges are producing. If you never go above 4krpm then no problem. Nobody really knows what is causing high oil usage, at least officially.

[Rooted]

I think most here that make sure their cars engines get properly up to temperature and do long distances or sporting and spirited drives do not have high oil usage in those circumstances.

Oil Temps up above an Indicated 105- 115 or more.

 

That is with Full Synthetic 5w 30 or 5w 40 Quantum Longlife III or Castrol Edge, Mobile 1, 

or actually any suitable VW 502 00  or VW 504 00

 

Yet can use some oil on short journeys where the engine is running rich and the Coolant & Oil is not long at Operating Temperature

if it ever actually gets near it.

 

I know that Sparkly & Myself have had cars that used oil on one occasion during cold weather,

then never used oil again.

 

Too many engines have been overfilled with oil,

which is another issue.

 

The CAVE Engines have had various issues, 

and a few early CTHE engines also.

There are owners that have had a CAVE & a CTHE with no issues.

There is one owner here that had a CAVE and problems, then he has had a CTHE and problems,

he knew not to overfill the Oil, but the Fault was with the Engines, not the Owner/Driver.

[vxh26]

Interesting questions! Castrol Edge 5W-30 FST Professionall III (one with yellow black light reactive dye) as used by Skoda is not suitable for high temperatures and loads twincharges are producing. If you never go above 4krpm then no problem. Nobody really knows what is causing high oil usage, at least officially.

Isn't the VAG 1.4 litre Twincharged engine red-lined at 6,500 rpm or something? I would have thought that owners of the VW Polo GTI, Audi A1, Seat Ibiza or Fabia vRS might exceed 4,000 rpm on just the odd occasion!

[Rooted]

Those engines have the same problem as in the vRS when there are problems.

They are the identical Engines, other than the A1 1.4 TFSI 185 PS that has some different ignition parts on the same Base Engine & Map.

 

What has Redlining to do with it.?

The engine can do maximum output below the Redline.

 

The given by VW , Skoda, Seat, Audi figures, for max Power of 180ps or 185ps was 6,000 then that was changed to 6,200 with the Engine Management Change.

That is Below the Red line.

 

In 'D' the 7 Speed Box depending on throttle position, and how you are driving the Box is Changing up at 2,200 rpm.

In 'S' which is 6 speed it changes up at around 4,000 rpm if you are not on full throttle acceleration.

In Manual you can hold it pretty much to the Redline and the box changes automatically still until 4th,

then you need to change,

 

They are wonderful engines and great fitted to the 7 Speed DSG,

it is just some have Quality Control of parts problems.