1.4 TSI - An insight into just how bad the intake coking is

[blower]

I'm in the middle of rebuilding my engine on my 1.4 TSI 160 CAVD - fitting forged pistons and doing a full head decoke and a 'valve' job before mapping for power.
There's nothing wrong with the engine - it was running fine, other than a a slight rough idle intermittently which is common on this engine.

I'll be doing a full write up on my rebuild soon, however i thought i would just do a post to show you guys how bad the intake build up is - worse than it looked when i took some poor photos down the intake some months ago when fitting new injectors.

It has 55k miles on it, i have owned the car since 30k miles, it has oil changes every 5k miles and gets a good run now and then. Take a look at this....









No wonder the idle has some issues - with the state of the intake ports and valves its a miracle it doesn't misfire all the time when idling.
Good old direct injection - 55k miles and my intake ports look like a dogs dinner.

I'll update once i finish the cleaning and valve job - currently 10 hours in (just on the head work), already done 15 hours of disassembly just to get to the point where i could take the head off, damn this engine is complicated - so many bits attached to it in hard to work places

[Psycho Kirky]

Wow, thats dirty[emoji14]so long as its all below the valve head/face and not in the cylinder haha.
Id love to see the state of my engine but thatll never happen lol

Sent Via tapatalk

[blower]

Have spent hours cleaning just the valves, using a brass wheel on my bench grinder, followed by dremel scouring polishing wheels......that stuff is on there and something like seafoam or water mist through the intake isn't going to do anything to it whatsoever.
As a test i soaked a couple of the valves overnight in acetone and carb cleaner - it did soften the outer layers but underneath was a layer that was rock solid.

The brass wheel on the bench grinder and a drill spinning the valve did the trick though, ripped all the crud clean off without damaging the valve (precautions were taken to protect the valve stem). Further cleaning with various tools on the dremel got rid of surface stains and polished it right up:

Cleaned and polished:



I must finish the head work now - have nearly done all the cleaning, which proved difficult on the intake due to the damn fixed divider plate, prevented me really getting in there. The exhaust side though is fully cleaned out and the ports and bowls all smoothed out.
Then I will lap the valves in.

[SKGR]

Sorry for beeing a newbie on this, but what can be causing that sort of buildup in the engine? Short driving in towns? Maybe drop in air filter or intake systems not filtering the dust and dirt propely so its goes in the engine? Is there a way to avoid this and protect the engine somehow?

Ty blower for keeping us informed.

Cheers,

SKGR

[blower]

Half my journeys are short journeys, but it does get a good run now and then. If i did nothing but motorway runs every day then i would expect half the build up i see.

The cause is mainly down to it being a direct injection petrol engine. The carbon deposits are primarily oil that has burnt onto the valves and around the intake area, its also mixed with some combustion soot - the result is a rock hard deposit that accumulates over time.
It's a problem that affects all DI engines - which is any modern petrol engine. The 2.0 litre engine is known for this issue as it seems to be worse on that particular engine, or at least the coked up intake affects the idle more severely to the point misfires are registered.
The 1.4 was thought to suffer less from it, but as you can see it's pretty much in the same boat as any DI engine.

Older injection cars used to have the fuel injected in the intake ports, and the fuel would wash over the valves - keeping them clean. Direct injection engines have the fuel sprayed directly into the cylinder and hence none of it ever touches the valves so they end up like this.
It's hard to prevent, some people install an oil catch can inline with the PCV system - the PCV system vents blowby gases back into the intake and some oil with it (despite a basic oil seperator being built into the PCV). It's debatable if a catch can has much impact on the carbon build up as people have found it hasn't had much effect - but this could be down to most catch cans being poorly designed. Also from what i have seen a lot of the oil that gets burnt onto the valves is leaking down the valve stem seals over time, and there's not much you can do to prevent that.

I will be installing a custom catch can on my PCV - at the very least it will reduce the oil in the intake and may help reduce the build up. It will however come back, all i may end up having done is delayed it.

[moulin12]

Blower,

Do you think the use of fuel additives would do much to reduce the build up? I'm not expecting that these would prevent, just reduce somewhat. Would be interested in your view.

No longer own the 160, of course, but I'm thinking of my current DI car as I do mostly short journeys

Thanks

[shrink]

Shouldn't think additives would help as the fuel
Still won't be going anywhere near the valve.

[blower]

As said above - fuel additives would do nothing to prevent this. That's the problem with direct injection, the fuel goes straight into the cylinder and no where near the intake or the valves like it used to on older port injection engines. The problem isn't how the fuel burns either - the problem is oil coming through the intake and burning onto the valves and sticking to the intake tract.

When I took the intake manifold off some months ago there was a little pool of oil in the bottom of it and all the inside was coated with a thin layer of oil - just goes to show that is what's being pumped through the intake via the PCV system.

A very good catch can should help reduce it - the problem with most (if not all) catch cans on the market is they are junk, with either no baffle in them so that they are just an empty can or a useless baffle with incorrect internal layout. I'm building my own to try and make something that's more effective, that will be documented to

As the valve picture also show's, i'm really polishing the valve up - trying to create a smooth surface that is harder for carbon deposits to stick to. It may do nothing, but have heard it can help.
Plus they look pretty

[Roy_01]

Don't forgot the effect of the overlapping valves at engine warm up.

The Camshaft Adjuster at start-up adjusts the inlet camshaft to speed up engine warm-up by overlapping the valve timing to keep some exhaust gases in the cylinders. This the negates the need for an EGR valve (Exhaust Gas Recirculation) to be fitted externally to the engine.

With the catch can i would also eliminate this problem with a little software tweek.

[blower]

Don't forgot the effect of the overlapping valves at engine warm up.

The Camshaft Adjuster at start-up adjusts the inlet camshaft to speed up engine warm-up by overlapping the valve timing to keep some exhaust gases in the cylinders. This the negates the need for an EGR valve (Exhaust Gas Recirculation) to be fitted externally to the engine.

Yes, i want to disable that god awful rough idling cold start pre-cat heating whereby, as you say it overlaps the valve timing and also does double fuel injection.

FYI it only does it if the engine temperature (ie coolant temperature) is between 20c and 30c on startup, and it hasn't done it in the past hour.
If when you start the engine it's outside this temperature range it doesn't do it...oddly you would think it would do it when colder, but nope - only in that exact temperature range.
You find it will do it in the summer on the first start of the day, and will also do it if you have left the car for a while after a run, and it's cooled down back into that range.

I haven't had it bypassed yet, i'm unsure if the tuners can tweak it out....failing that i have an electronic design that will alter the coolant temperature output sensor during startup if it is within that range, temporarily making the ECU see a a temperature that is just outside that range.

In the meantime if i start it and it does it, i shut the engine off, wait a few seconds and restart - doesn't do it then.

[blower]

I've been lapping the valves in all afternoon....the seats were pretty pitted, a couple of the exhaust valve seats had a hell of a lot of tiny pits. Thankfully none of the valves had any severe deep pitting, but its common on the 1.4 TSI to have pitting on the exhaust side...although i had plenty on the intake too. This no doubt meant some of the valves were not fully sealing.

Ideally this really needed the valve seats recut, but i don't have the time to send the head away for reworking - nor the money!, to damn expensive to get 16 valve seats recut. The valves themselves were fine, although a few of the exhaust valves had some noticeable pitting.

One of the bad exhaust valve seats (this is after it was cleaned with a brass wire wheel on a dremel)



Then after some time hand lapping with valve grinding grit and a wooden lapping tool (hate hate hate that thing ):



As you can see, still some pitting left - hand lapping was not enough to get rid of all of it - at the rate i was going it it was over an hour per valve of work. So it was time for the drill, drill bit and vacuum hose on end of the valve stem.

Again ideally this should have been radially cut but this is a good enough job, you have to be careful when using a drill to lap, the small section of rubber vacuum hose doing double duty to hold the valve and keep wobble along with any off centre angle out of the valve as it rotates so its face is always flat to the seat when grinding:



All cleaned up, no pitting, good centered finish with plenty of upper angle left on the seat.

[ditamai_ing]

Hello Blower! I presume you used a repair manual to get this job done. Where did you find it? I'm planning to remove the cylinder head myself because of the misfire issue.