Misfire on idle

[JimR]

Hi all,
New to the forum an searched as much as poss to see if anyone else has had this problem.
I have a MY07 GTI DSG with a misfire that only seems to be on idol at this stage.
Sounds a bit like a boxer engine while the chokes on, once the chokes off it smoothed out a bit but is still missing.
Once driving its pretty normal.

I took the car in to VW Village, Syd, to let them have a look. They tried coils and plugs and have narrowed it down to needing a new injector on cyl 2.

Is this a common fault injectors failing? The car is just coming up to 90k. It had its major and cambelt done 6mth ago.

Was to the labor is the pricy bit and advised to do all 4 while they're at it at a cost of $1600!

Took it to my local mechanic at the weekend. Misfire is definitely cyl 2 and all coil packs are good but he's thinking it can't be the injector at 90k.
I'm leaving it with him in Friday so he can delve a bit deeper.

Any advice or thoughts would be great.

[Bug_racer]

Needs a carbon clean . Been there done that to nearly 100 cars over a 5 year period . Changing injectors is an easy way out of trying to fix the issue !

[JimR]

Misfire on idol.

I'm currently running some Liquimoly injector ranger through, but I'm guess a carbon clean is a little more involved right?
Something I can do or a job for the garaged?
Cheers for the advice!

[Lucas_R]

Misfire on idol.

Carbon cleaning involves removing the inlet manifold and manually cleaning the intake ports and intake valves of carbon buildup. Its a manual process (ie no easy method to do it) and the carbon build up is unfortunately a result of the direct injection these engines use.

If this is indeed the issue as bug racer has suggested, hit him up to do the carbon clean for you - it makes sense seeing you are both in Sydney and he knows what he is doing.

[domanski]

I had a cars with faulty injectors @15k. If you changed a sparkplugs and swaped a coil packs ( fault didn't moved to another cylinder) then change a injector. 100%

[JimR]

Misfire on idol.

I guess taking the inlet manifold off for a gander first would be the way to go right? If its super clogged up in there then it needs a clean regardless. If that doesn't fix it the replace the injector. Sounds like a plan to me?
Would any of you experienced chaps recommended replacing all 4 though or just the potentially faulty one?

[wai]

Have you checked the ignition leads?

Remove them at the plugs and see if there is any evidence of arcing. Do the same at the distributor.

[Bug_racer]

I'm currently running some Liquimoly injector ranger through, but I'm guess a carbon clean is a little more involved right?
Something I can do or a job for the garaged?
Cheers for the advice!

its not enough , you need to soak the injectors and run high pressure cleaner through them . I had an injector machine made specifically for FSI injectors as Bosch wanted some 80K for their unit . AFAIK Im the only one in Aus to have a machine made just for FSI injectors

[Bug_racer]

Carbon cleaning involves removing the inlet manifold and manually cleaning the intake ports and intake valves of carbon buildup. Its a manual process (ie no easy method to do it) and the carbon build up is unfortunately a result of the direct injection these engines use.

If this is indeed the issue as bug racer has suggested, hit him up to do the carbon clean for you - it makes sense seeing you are both in Sydney and he knows what he is doing.

Min of 4 days to do it , it involves cleaning the injectors , valves , intake ports , intake dividers , intake divider flaps , throttle body and replacing of the cam follower . I can never get any decent pictures in the intake , but the valve is cleaned to the point that it has a smooth finish unlike every other image Ive seen of them being cleaned overseas . Locally I dont think anyone else does it without pulling the head off ?

[JimR]

Misfire on idol.

So I got 2 responses, deffo injectors and intake need cleaning and another deffo needs new injector

[Bug_racer]

I had a cars with faulty injectors @15k. If you changed a sparkplugs and swaped a coil packs ( fault didn't moved to another cylinder) then change a injector. 100%

Injectors arent faulty , they just get carbon build up on the tips

[JimR]

Misfire on idol.

Now I'm confused

[Bug_racer]

Have you checked the ignition leads?

Remove them at the plugs and see if there is any evidence of arcing. Do the same at the distributor.

Wrong engine , AFAIK there is no dizzy+leads on any FSI engine

[Lucas_R]

Now I'm confused

The injectors are in the intake chamber of the head (engine head) along with the inlet valves and spark plug, and these engines get carbon buildup over time in this area. The carbon buildup will also slowly choke the injectors as well - which is most likely what has happened on your vehicle, causing the mis-fire.

The injector(s) can be replaced, which will possibly "bandaid" the situation for a short period of time, but the truth of the fact is that you will need to have the inlet chambers of the head cleaned properly.

Have a look at this link to show you what we are trying to explain: http://www.more-bhp.com/20tfsi_42fsi..._cleaning.html

[JimR]

Misfire on idol.

Makes total sense and I get it. Watched some YouTube vids on this too.
I guess what I was confused about was whether they need cleaning or replacing bit I guess cleaning is first up and if that doesn't work then replacement may be necessary.