Just after a bit of advice. SWMBOs TSI has been misfiring recently under load and more recently on start-up it has been firing on 3 cylinders for a few secs but even once warmed up and not misfiring, it generally feels like there's a lack of power when accelerating. It's a 2009 model with 32k miles on the clock. According to service record, the dealer changed the plugs in 2013, so they've been fitted for about 12k miles.

Anyway, its due a service in July so I'll be asking them to check for faults, but I decided to change the spark plugs yesterday and it has instantly cured the problem. However, I'm concerned there's a more serious underlying problem as the plugs looked ok around the insulator and tip of electrode but the side of electrode and ring were very black and the threads a little oily.

Any thoughts welcome.

Edited 10 May, 201511 yr by Matt Pez

Get the codes read but I'd be guessing a coil

 

If a coil is on the way out then an over-gapped spark plug (I aim for 0.028" when I check mine) can cause a misfire from the coil.  Fitting new spark plugs means the coil doesn't have to work as hard to produce the required voltage. 

 

Photos of the sparklers would be nice.

Cheers Brad, not sure about the coils, all 4 sparks came out looking the same, so assume its more a general running rich issue, rather than a single coil issue. SWMBO does mainly short trips so I'm also going to check that the air filter is not blocked when I get chance but it's also due for replacement this time as 6 yrs old.

Update, misfire returned, new sparks 2 months ago all coked up already, cleaned and refitted and decided to change all coil packs, also ordered a can of BG44k as read that others have had good results decoking using this. Started running it on 99ron but I guess 6 years of mainly short trips on 95ron has taken it's toll on the inlet manifold. Running much better today with new coils, hopefully the BG44k will help, anyone got any other ideas?

Decent fuel & fuel system cleaners will only clean the injectors. 

 

You need to get a borescope into the inlet via the air temp sensor hole & see how carboned up the inlet valves are.  You'll probably be only able to manoeuvre to cyl 2 & 3 but it will give you an idea.

 

I give mine a chemical clean through the air temp sensor hole about every 15,000km prior to the oil change.  It helps a bit but there comes a time when you have to pull the inlet off & do it the old fashioned way.  You mileage seems very low though.

 

Have you had the codes read?

 

I do it like this with a mixture of turps, kerosene, degreaser & water.

 

This guy waffles on a bit but he does it the same way as me

https://youtu.be/hHF-Jdw0eto

Thanks for that, there was also another clip of a guy spraying water into his air intake, would you recommend that method or do you have to go through the air temp sensor hole to get best results?

Had a dealer service and mot a couple of weeks ago, last one on a 3 yr service pack that we had subscribed to after initial free servicing deal ended, mentioned the poor running issues and asked them to check for errors, nothing found except the auxiliary coolant pump was flagged as failed, but my local reliable indi garage said not to worry about that unless the engine management flags an issue via the dashboard lights.

Do you think using the car more regularly would help, as I could use it for work a couple of days each week, I have a 75 mile commute, so would give the O3 a rest and the O2 does put a smile on your face, proper wolf in sheep's clothing!

Edited 12 July, 201510 yr by Matt Pez

Thanks for that, there was also another clip of a guy spraying water into his air intake, would you recommend that method or do you have to go through the air temp sensor hole to get best results?

Had a dealer service and mot a couple of weeks ago, last one on a 3 yr service pack that we had subscribed to after initial free servicing deal ended, mentioned the poor running issues and asked them to check for errors, nothing found except the auxiliary coolant pump was flagged as failed, but my local reliable indi garage said not to worry about that unless the engine management flags an issue via the dashboard lights.

Do you think using the car more regularly would help, as I could use it for work a couple of days each week, I have a 75 mile commute, so would give the O3 a rest and the O2 does put a smile on your face, proper wolf in sheep's clothing!

 

I've sprayed via the air intake & found that the fluid tends to collect in the intercooler - even if the engine is free revving at 2500-3000rpm.  Then when you go on a test drive the fluid is sucked up and the engine pops & farts and swallows a big gulp of liquid.  As there is no control over how much liquid is being sucked in there is a possibility of hydro-lock and associated damage to the engine.

 

As a first timer you might rather start with something like a foaming inlet cleaner.  **Top Tip #1 always tape the extension straw onto the can so it isn't blown into the inlet manifold***

 

I'm not sure what brands you have in the UK but we have Nulon, Liqui Moly and Subaru inlet cleaners here.  The Yanks also have SeaFoam.  You guys seem to have Wynns, JLM, BG 406 & Revive?

 

Before throwing all that stuff at it I'd recommend some diagnosis first.

 

Doing longer trips?  I'm not really sure it would help if it's already carboned-up but a decent drive once a week won't do any harm.

Well I've run BG44k through over the last couple of tanks and it seems alot more responsive but still fluttering accelerating under load in 4th and 5th around 2k revs so decided to give it a Seafoam inlet manifold treatment. What an anti-climax! Expected to smoke out the whole street but hardly anything, just a light smoking and a dodgy smell! First impressions this morning are the fluttering has gone. Only used 1/3 of the Seafoam so might give it a couple of weeks and repeat. I used the 1/4" fuel injector hose with football inflation needle method via the sensor port on the inlet manifold. Only thing I was not sure about was how far to push the hose in the hole, opted for half way as worried all the way would restrict the spray over the valves.

Edited 18 July, 201510 yr by Matt Pez

I barely get any smoke until I take the car for  a drive & hive it a boot full.  I figure the 800 cell cat next to the turbo outlet & the 600 cell further down stream might have something to do with it

Ok cheers, defo seems to have helped, I let it sip the chemicals over about 5 mins, then let it drink a big gulp at the end, it didn't stall though, as it emptied the cup I was using first, so switched off and left it for 20 mins before taking it for a spin.

What was the outcome after a few months with the Seafoam? Tempted to do this myself. Would use brad's method but not confident enough to mix it right or that I'd use the right stuff!

You can't get the mix wrong.  You are simply trying to introduce solvents into inlet manifold.  If the head wasn't aluminium I'd use foaming oven cleaner (I can't find a non-caustic based oven cleaner here).

 

I use about 1 part degreaser, 2 parts mineral turps (white spirits), 2 parts methylated spirits (methanol??) and 3-4 parts water - plus whatever else (kerosene, etc) I might have floating about in the workshop..  Mix 1.5-2 litres. spray as a fine mist

 

I can understand your reluctance.

 

Liqui-Moly do an inlet cleaner that works. 

Subaru also have an upper inlet cleaner.

There's a bunch called Revive that do a turbo cleaner - it would clean the inlet as well (call them)

 

top-tip - tape the plastic nozzle extension to the can so it doesn't get blown into the inlet.

I used injector cleaner.

 

http://www.wynns.eu/product/injector-cleaner-for-petrol-engines/ 

 

It was £6. I used a length of fuel hose and a football inflator needle. Just like this video. The only thing I did different was use a pair of pliers to squash the end of the needle to further restrict / atomise the injector cleaner.

 

 

I used half a bottle and took the car for a run and then came back and used the other half of a bottle.

 

I only did it as a maintenance treatment as I though I felt a light staggering on my TSI.

 

BTW - The fuel hose I already had in the garage but I think I bought it some time ago from halfords for a few pounds.

Edited 26 September, 201510 yr by radders567

You decide against the seafoam then.Did injector cleaner help with the stagger?

Yes it seems to have.  The injector cleaner was just cheaper and more readily available to me.

If you read section 3.2 of the SDS of the injector cleaner and then search the ingredients back to the EC product identifier you can work out the main ingredients and use a cheaper injector cleaner.  I recently bought some for AUD2 (GBP1) on special at my local parts store.

The main ingredient in the Wynns stuff is Naptha (petroleum), hydrosulpherised, heavy.  It's basically a solvent.  Most injector cleaners are 50-75% naptha.

 

The 2nd ingredient is isobutylmethylcarbinol which is a solvent for waxes, resins, etc

 

The other good ingredient that you might have lying about is traditional red automatic transmission fluid.  It's full of detergents & quite effective at removing sludge & carbon

What was the outcome after a few months with the Seafoam? Tempted to do this myself. Would use brad's method but not confident enough to mix it right or that I'd use the right stuff!

Still got a fluttering at 2k revs when accelerating steadily in high gears, 4th or above but don't notice when booting it. Damp starting also seems to occasionally fire up on 3 cylinders, so not really much further on with diagnosis. Someone also recommended cleaning the MAF sensor but not got round to that yet.