General maintenance 1.4Tsi Twin-charged fundamental problems

Hello twincharged owners. My name is Mark.....aka Lucifer and I have spent the last 4 years in ownership of a 1.4tsi Seat Ibiza. I have now at long last managed to conquer stage 3 tuning on this engine after several setbacks and much more money spent than I ever wanted. I still honestly believe after all the inerrant problems I have discovered with this engine and products designed for it by certain company’s, that the engine can still be tuned on a budget and can be reliable. Hence this guide........hope you all enjoy.


1. Misfiring, Oil Consumption, Engine Failure
2. PCV System
3. Turbo
4. Timing Chain
5. Radiator
6. Supercharger Magnetic Clutch

1. Misfiring, Oil Consumption, Engine Failure

This is the main worry for most 1.4TSI owners. Its not because of a single problem, but involves a number of factors which together they ultimately lead to engine failure.

A) Piston Rings

After it was finally admitted in late 2011 that there was a problem leading to engine failure(bearing in mind the engine came out in 2010), SEAT offered customers new piston rings.
Actually, what they were doing was fitting completely new pistons. It was VW trying to delude the customer that it was a minor piston ring batch problem rather than a major piston design problem.
In truth, its the pistons that were weak full stop and couldn't handle much punishment before they failed. The specific problem was that the part of the piston between the rings used to crack and then come away, damaging the piston rings and eating into the cylinder bores (although these have proven to be very strong due to being plasma coated).
There have been examples of totally standard cars having piston failure and these tend to be early cars with the original ignition hardware and OEM ECU software. Then when you add an ECU map you are bound to have a failure.
When these pistons crack, oil consumption is increased as it enters the combustion chamber, also lowering the effective octane value of the fuel being injected. This is not the only reason for oil consumption and equally the culprit is the turbocharger, especially on cars with aftermarket exhausts. I will talk about that later.
Its easy to blame the pistons but its not the whole story. If the car was used for daily driving and not running massive amounts of boost, there’s no reason why these pistons should be put under such an amount of punishment that it would result in failure........unless there are other contributing issues, which there are. Read on.........

Solution: Revised pistons 2012 onwards and come as standard in the CTHE/CTHF engine codes.

B) Ignition System

These were problematic at the end of 2009/start 2010.
They would drip when stationary with the engine off causing oil to be washed off the bores and pistons, resulting in increased piston ware. Upon starting the engine, the engine would run lumpy because of the extra fuel in cylinder.
Another feature was a narrow spray pattern to the injector. This would result in an incomplete burn when fuelling is at its highest and the excess would collect on the surface of the piston, which would then ignite due to the heat of the engine. This would scorch the surface and cause carbon build up which collected on the exhaust valves. This would cause misfiring due to valves not shutting correctly. The crazy part is that by driving the car hard under boost then it would clean away enough carbon to allow normal operation without misfire but would also speed up the failure process.
When re-maps started getting released as fuelling was increased it was exaggerating the problem. This coupled with the weak pistons discussed earlier resulted in the early engine failures.

Solution: Revised Injectors with a wide spray pattern got released by SEAT mid 2010, chances are most cars have these now, which lead to other problems.
This new problem was at full fuelling the wide pattern would extinguish the spark of the spark plug which is sat almost directly in line with the injector. It is because this 1.4TSI engine is actually based on the old 1.4 16v engine from years ago so that wasn’t addressed. It was Revo Technik that actually discovered this after they had a piston fail when developing their stage 2+ map, subsequently falling out with SEAT. They then halted their development of this engine but came out with a couple of recommendations which I shall discuss below.

Coil Packs
There were a batch of coil packs in 2010 that were faulty according to SEAT but again I believe that was an excuse to make them look less liable for their problems.
There were a later version of the coil packs in 2011 which again the CTHE/CTHF engines have as standard. I believe the aim was to increase the strength of the spark created by the plugs in order to try and stop the misfiring. From my experience these helped very little as the cause of the problem was still existent.

Seat Software+Spark Plugs+High Presure Fuel Pump
This is the main cause of the engine failures since 2010.
So as we know we have the weak pistons and new injectors with a wider spray pattern causing contamination of the spark plug tip.

One other thing I haven’t mentioned yet is the Software. When the engine was re-released as a performance engine in 2010, it coincided with new emission regulations. The pre 2010 variants under the old emission regulations had the same power output as the new FR (150) and engine failures with these were rare; yet the FR failures were as common as the CUPRA (180bhp) variant so it was nothing to do with the increased power output.
It was as a result of the software which ended up making the engine run a lean mixture when not under boost in an effort to meet these regulations.

As it stood, the engine itself ran hot due to its twincharged nature.
Pre detonation was therefore a problem. Fuel was ignited as a result of the heat build-up rather than the activation of the spark plug which, as was mentioned above, was not fully operational under high fuelling instances. So this was throwing timing out when booting the car after gentle driving/traffic situations, the spark plug was then firing without any fuel to ignite making the problem worse. This resulted in engine misfire and stutter until fuelling was increased enough to the extent that it was contaminating the spark plug as we discussed. The fuelling therefore went through cycles of being too lean and too rich.
There were further problems as a result of the ECU software. There were some floored parts of coding in the software that couldn’t control misfiring properly, which is so hard to believe when dealing with such a well established company such as VW. Revo again were the first to inform me of this parameter within the code.

Because the fuelling system is a 'demand' type, air quantity is measured and the correct amount of fuel is then supplied for the desired mixture(as set in the ECU). So when a misfire occurred, the ECU had no comprehension that the engine could possibly be running rich as a result of the misfire, only lean. It would then start increasing fuelling constantly expecting the misfiring to stop, to the point that the engine would completely stall and the cylinders were full of fuel.
This fuel would leak into the sump and mix with the oil which is detrimental to its function. This is another catalyst to the engine ware.
Revo found that cylinder 4 on the other hand, being the last cylinder to be supplied fuel along the common rail fuel supply, was starved of fuel. This is because the capacity of the fuelling system was max'd out; injectors 1, 2 and 3 were at full flow and there wasn’t sufficient fuel left to be able to supply injector 4. This lead to piston 4 being the one that failed in most cases.
SEAT released a new High Pressure Fuel Pump towards the end of 2011 as an attempt to stop the cylinder 4 starvation of fuel, which may or may not have helped, but didn’t address the cause of the problem.
Now when you have a serious bout of misfiring it is obvious, it is felt throughout the car and lights appear on the dash. The majority of the time, the engine would have invisible misfiring. When I logged the car, I found that misfiring was present constantly but not so bad as to be detectable. So this problem was going on to this degree undetected for a lot of cars, leading to piston 4 finally going.

Revo actually took it upon themselves to rewrite this part of the coding, which isn't the norm. Usually they just re configure boost pressure, Air-Fuel-Ratios, timing etc. After this was done people, including myself who were totally standard before, flocked to Revo just for a car that would work properly. It took SEAT several months after this to release software that would solve this problem but of course they still needed to abide by the new EU regulations which REVO didn’t.

In addition to the amended software, Revo also recommended a plug change to NGK Iridium BRK7EIX. This plug was shorter and colder so it sat out of the way of the flow of the injectors whilst reducing pre detonation. Again there is a disadvantage of these plugs. It is more difficult to create an efficient burn, especially on cold start-up. There will be a lumpy initial idle because the plug is on the edge of its operating temperature zone.
Carbon build-up on the valves is still a problem too.
SEAT then released a new model of plugs for this engine to work with their software which are shorter than the original plugs which work with their new software; but not a re-map.

Solution:Revo/New SEAT software + recommended plugs.
The new fuel pump released at the endof 2011 is not necessary but is handy for tuning as I know its adequate for over 300bhp, where the other one may be not.
All the above upgrades will be available on the 2012 cars onwards.

Misfiring is still present with these engines regardless of all the new hardware and software. It will just be on occasion when the right environment is created:

1. High Carbon Build up on the valves restricting exhaust gasses leaving the engine plus carbon build up on the plugs restricting the quality of spark.
- Caused by long slow driving or not using the turbocharger for extended periods

2. High intake temperatures
- Caused by heat soak when in traffic with high ambient temperatures.

3. Lower quality fuel (95ron supermarket)
- Caused by being a tight ass

2. PCV System

Or Positive Crankcase Ventilation for those who want to know or care. Basically its job is to release pressure built up in the sump as a result of blow-by gasses entering from the combustion chamber.

This is completely normal even on engines with perfect piston ring seal but there will always be a certain degree of air escaping the cylinder past the piston rings into the sump.

The amount of pressure that ends up in the sump is proportional to the amount of revs the engine is at and also the amount of boost being used.

Once this pressure has been released through a hole in the block, then it is directed back into the intake to be re-used by the engine.

It used to be vented to the atmosphere on older cars but new cars have to meet more strict regulations.

It enters the intake side of the engine in 2 ways.
The first is just past the air filter which is a rather thick pipe and the other is straight into the intake manifold through a rather thin pipe.

There is suction or vacuum on these pipes created by the air entering the engine, which helps suck the crankcase gasses out.

These two pipes join together via a regulation check valve that controls which pipe it goes through.
This valve also controls back flow of the air to the engine once the throttle is released and there is no loner any vacuum provided by the intake system.

The problem with this system is that it is restrictive from the factory. The reasons for the restriction are the regulation check valve that we discussed and also a second check valve that exists inside the block. Before the gas leaves the block through the hole there is a what is called an oil labyrinth which separates any oil from the air trying to leave. Any oil collected drains back to the sump. It look almost like a maze. It has some narrowings and also a check valve after, it which is very restrictive.

So with these engines, whilst new and running standard mapping they shouldn’t produce blow-by sufficient, not to be vented by the PCV system. As we know though, once mapped and running more boost then blow-by increases but more importantly, should the pistons deteriorate because of either the early injector problem or the more recent software and spark plug problem, then blow-by will be higher too. This results in high crankcase pressures.

The problem is with this is that it puts pressure on the whole engine in relation to seals and gaskets. The turbo oil seal is the weakest of these so you would expect one of the seals either on the intake side or exhaust side to start weeping oil through.

The way this happens is that the oil return pipe from the turbo gets pressurized and oil is restriced from returning to the sump as it needs to.
At the top of the turbo, fresh oil is being supplied to the turbo via the turbo oil feed pipe. This results in the pressure of oil in the turbo being increased to the point it only has one way to go.......past the oil seals.

Should this issue not be resolved then the seal will get pushed out further and the car will smoke from the exhaust. A whitish colour to begin with but then a more bluey colour.

At this point the turbo will be consuming a good amount of oil and will need a rebuild.

If the car has a standard catalytic converter then the smoke is likely to be subdued and instead it is replaced by little black particles being accumulated over the back of the car and you will observe a glistening layer to the boot and rear bumper when raining.

The second problem with, high crankcase pressures is oil being pushed out through the pcv pipe into the air intake, which gets sucked into the engine again lowering the effective octane of the fuel. Thus pre-detonation is even more likely than when we discussed before and the carbon coating on the valves and spark plugs are even more likely.....misfire galore and bye bye piston.

Now of course it is triggered by bad pistons and or high boost with extended periods of hard driving (track) but there are a few other points to consider regarding the turbo supporting hardware that affect this. So if you do have a turbo oil leak it doesn’t necessarily mean you have bad rings, but if you are getting oil through the pcv pipes too then there is a good chance, especially if you are running standard software. I will talk more about the attributes of the turbo below but this is a major cause of oil consumption.

When my engine was rebuilt, it didn't use a drop of oil and had excellent compression yet the turbo was still leaking oil into the exhaust from pre build and I could use anywhere between 125ml to 250ml in 250miles, which if the car had been taken to SEAT for an oil consumption test, would have been treated to new pistons or a new engine as part of their guidelines. I wonder how many people that failed oil consumption tests have had this done.

The newer CTHE cars have a new pcv system and oil labyrinth to address this. They actually released this new breather pipe in 2012 because they realised that they were handing out new engines unnecessarily. Not only that, they could actually reduce and hide oil consumption by improving this pcv system, enabling them not having to address this issue until the car was out of warranty. In my opinion, whilst the new pcv pipe revision is an improvement, it does not address the internal restrictions inside the block.

To that end, I had to resort to removing the timing chain case and drilling the check valve out. This was only necessary because I was not only running a decat exhaust, hybrid turbo and high boost; but low silicone pistons also. These expand when warm and are at their tightest in the bores when hot and under boost which is what you want. Under idle on the other hand there was a lot of blowby which is just a feature of this type of piston.

I also deleted the small pcv pipe and the top check valve and designed a twin catch can system so not only was it more effective, it had the added benefit of having no oil in the intake.

Custom catch can setup to catch any oil from the PCV system. (please see other guide)
Drilling out the internal engine check valve (If not CTHE and stage 3)

3. Turbo

The turbo is not necessarily an issue if it wasn’t for the known engine problems but there are 2 major features of this turbo that need consideration to avoid oil consumption.

The oil seals of the turbo are designed to hold the oil inside the turbo around the bearing rather than it leaking down the turbo shaft to the turbine and impeller (2 wheels at each end of the shaft). These are designed and balanced perfectly to take into account the forces applied on them in both directions. The internal force on the seal is made by the heat expansion inside the bearing and the oil pressure flowing through it. On the other side there is back pressure. On the intake side of the turbo it is the air hitting the wheel and the force of compressing the air to send to the intercooler. On the exhaust side it is the back pressure of the downpipe, catalytic converter, cat back pipe and silencers.

One rule of thumb with a turbo engine is that the best sort of exhaust is no exhaust at all; and no exhaust = no back pressure. Thus after market exhausts deliberately try and minimize back pressure, resulting in the oil seal losing the pressure balance it once had. On a normal car this is not usually too much of a problem and the seal could potentially hold the oil in with minimal seepage, but together with the second feature of this turbo, it simply cannot.

The second issue is the internal pressure inside the turbo. These turbos, as confirmed by their manufacturer, are designed with internal pressures of 40-60psi in mind. When measuring the actual pressure through the turbo even with a new engine it was found that it could raise to 70psi. This is because of the under piston oil jet system, which coats the pistons in clean cooler oil before they raise up into the bores for the next stroke. There are a few other manufacturers that have had similar problems.

Now if you imagine the engine and pcv problems being present as discussed earlier with high internal pressures and no back pressures then it becomes a very serious issue.

There is no SEAT solution to this problem as they don't want us to run sports exhausts to begin with, especially de-cat exhausts. I designed an oil restrictor bolt based on another VW variant. It has slightly smaller holes than the OEM one on the 1.4TSI and have I have logged the pressures at between 40-45psi. This results in a healthy internal pressure allowing a decat exhaust to be run safely with a healthy engine.

This is even more important to fit if you are using a hybrid turbo. The reason is the turbine wheel on the exhaust side is MUCH bigger and the housing has been bored out resulting in more flow but less back pressure. Thats great for performance but not good on the oil seal. For this reason, I have also had the oil seals strengthened in my hybrid turbo.

Custom oil restrictor (if running decat)
Strengthened oil seals (as part of the turbo hybridization process)

NOTE: LOBA270 has normal oil seals, and is not suited to a de-cat exhaust, despite what they say!

4. Timing Chain

The timing chain system is a known fault. The part that fails is the hydraulic tensioner which uses oil pressure to tension the chain. The cases that I am aware of have been when engines are running fine before being switched off, then not able to be turned over again. Having had direct information from a major race engine builder in the UK, this problem has occurred mostly after an oil change.

When the oil has been dropped and the car left over the pit until the sump is dry, the tensioner ends up being empty with no pressure on the chain, this is worse if an engine flush has been used. Upon starting the engine it will take some seconds before oil pressure inside it has been re-established and thus during cranking the chain is slack giving it an opportunity to jump. The older and more worn the timing chain, the more likely it is to jump.

There is no update or new part for this problem

Regular services, ideally every 5-10k with the best oil you can afford that is 0W-40. If
not, 10W-40. Also when doing servicing, fill the oil filter up with oil before fitting and
don’t allow the sump to drain dry during the emptying phase of the oil change. Once it
starts trickling, put the sump plug back in and fill the engine with new oil.

5. Radiator

Another built in problem here. This tends to go at the 3 year point, coincidently at the end of the warranty period. It is Pretty bad quality. It uses plastic end tanks bonded to the metal core, and its this bond that comes apart allowing the radiator to start leaking water.

At £90 these are quite cheap but can be upgraded to an Aluminium version with 78% larger capacity by Pace Products, which greatly helps in reducing block temperatures which we know are high.

6. Supercharger Magnetic Clutch

This problem occurred in cars built in 2010 and 2011. The car would make a squeak or ticking noise where the supercharger would struggle to engage upon trying to activate the supercharger at low rpm. The problem was a part of the water pump where there exists a magnetic clutch responsible for supercharger activation. The upgraded part had modified clutch material that solved the problem.

Some people had it replaced and the problem returned but I believe they just had a new outdated variant fitted which lead to the same problem.

Upgraded water pump, standard on cars post 2011.


I hope this is useful for people who see the 1.4TSI as a mystery. I was one of these people to begin with. I have done my best to provide the most comprehensive and accurate account of these problems as well as all the solutions that are possible. The information gathered has been supplied by SEAT head technicians, ECU tuning companies, Performance engine builders, Turbo technicians and my own personal findings.

If there are any questions or comments that you feel the need to ask, please do.
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Thanks for putting this together, really helpful for owners and prospective buyers.
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