misfire and running too lean!

[DomBacon]

Car doesn't seem to be running quite right lately so plugged in vcds to have a look
No fault codes

But on logging i have misfire on cylinder 3 and 4
Replaced coil packs, plugs and done a compression test and all held about 160psi!

Then when I was looking at other bits i found out its running too lean



I replaced the cam follower and its still the same.
Heard that vacuum leaks can cause it to run lean so replaced my forge dv for the better oem one and my pcv blank to the oem pcv. Car still runs crap!
Rail pressure is fine as well.

What else could it be?
Anyway i can check injectors using vcds?

Any help would be much appreciated 
Cheers Dom.

[jhook661]

If you've got a miss fire on both cylinders and you've changed all above ^^ it's most likely to be injectors

[DomBacon]

Just don't want to spend the money on injectors and it's not the problem as they cost quite a lot!

[jhook661]

It's running lean and misfiring in two cylinders it's looking that way to be honest

[DomBacon]

Could be the carbon build up on the valves

[jhook661]

Yes it could be that too I completely forgot about they get chocked up badly well remembered 

[Dan_FR]

What intake are you running? What were your LTFT's before you had this issue?  How many misfires are we talking about and are they all the time including at idle, or just when driving/under load? Are you K03 or K04? You mention you replaced coil packs, but what about the plugs? If not, change them. Did you examine the plugs colour/condition? if so then details or pictures would be good

Lots more info needed, but the short answer is no you can not check them with VCDS. You can sometimes hear them after you have had the car running by removing a spark plug and listening in to the affected cylinder for a slight hiss

[DomBacon]

Forge twin take the moment but changing to a different one when I get a chance to change them over
Edition 30 so ko4
I said I replaced the spark plugs as well
Not sure on LTFTs
About 7-10 every minute I'd say and only at idle

[Dan_FR]

Missed the mention of plugs. Does sound very much like the injectors, getting to be common with K04 cars as they are getting older.

Did you check the condition of the plugs when you changed them? Were the 2 wet / soaked in fuel? Removing the plug and listening for a faint hiss from inside the cylinder shortly after switching the engine off would be next

[DomBacon]

The plugs were quite burnt but don't remember them being wet or anything
Someone told me that all cars misfire on idle and 7-10 misfires a minute or 2 isn't anything to worry about!
He said the reason the car is running lean is because of the Revo map, his seen it happen before apparently.

[DomBacon]

Are the S3 injectors the same as the standard ones in ed30?
Ive seen places say they flow 13% better
or
RS4 injectors? going to go stage2+ once this problem is sorted and then bigger turbo
The rs4 injectors are about £120 cheaper than the s3 ones

[bacillus]

Are the S3 injectors the same as the standard ones in ed30?

Yes

Ive seen places say they flow 13% better

That's compared with the k03 injectors.

Imo stick with the standard k04 injectors as their spray pattern is better suited to the gti engine.

[DomBacon]

Was only going to replace them for rs4 ones as there much cheaper, I can send mine off to get tested and cleaned but that takes 5 days