1.6 FSI - Another Misfire problem, i'm stumped?

Topsie

Member
Okay, so my FSI Sport has had a misfire on cylinder 3 for a while now, occasionally it will throw a random misfire in there but generally always cylinder 3. I've done the following to try and resolve the issue;

Swapped coil pack cylinder 2 for 3, misfire didn't follow the coil pack.
Changed all spark plugs - cylinder 3 didn't look any worse than the others and all were tan in colour with no soot.
Cleaned both the earth on the rocker cover and the earth point under the OSF headlight.

All this has made little difference...

Symptoms while driving are a complete lack of power (but doesn't sound or feel like the car is misfiring) with occasional 'moments of clarity' where the car runs fine.

Also have P1031 - Flaps not reaching setpoint, don't think this is effecting performance, the arm is free to move and doesn't appear broken, maybe the solenoid? But this doesn't bother me too much, i don't think it's related.

Any ideas? I'm going to carry out the dreaded compression test, but owing to how clean cylinder 3 was I'm hoping this will reveal nothing new!

Nick
 
What you might need to do is remove injectors and have them checked. My car had multiple faults, one was a faulty injector.
 
should of done that when I had the upper inlet manifold off when I changed the water pump pipe and thermostat housing! Doesn't a faulty injector normally play havoc with the fuel trims though?
 
I had similar symptoms, and tried first the coil packs route too. Their replacement made no difference.
In my case the car ran fine when started from cold, then lost power after approx 10 minutes.
The culprit was an injector. I had al 4 replaced, while at it.

If your actuator arm is moving apparently freely, that's just maybe because it's be broken in its "lower part" (where it attaches to the flaps : you can't see it without taking it out)
It affects performance though, but not like a faulty injector.
 
I've been doing a fair bit of research into the FSI engine in general, due to the direct injection to the cylinder, there is no fuel to 'clean' the inlet valves and a small amount of blowback from the combiustion cycle which can cause the deposits of carbon. My worry is that with high mileage the inlet valves are coked up to the point where they are causing a problem, which is quite a common problem in other FSI engines. I'm very tempted to remove the cylinder head and remove the carbon from the piston crowns and the head in general and will give me an opportunity to look at the inlet flaps and injectors / inlet manifold, all dependant on cost.

the other idea is for a carbon clean/terra clean, but due to the direct injection again i'm not sure if this will benefit.

Before all this, i'm blanking the EGR to see if that makes a difference!
 
Hi Nick, did you get anywhere this? I've got a similar problem with my FSI engine but I suspect it might be an air leak at the back of the inlet manifold. There's a small rubber pipe there that I'm suspicious of.

Did you take your inlet manifold off? If so was it easy? The manual says to tilt the engine forward using a hoist...


Sent from my iPhone using Tapatalk
 
I've got a thread in diagnostics about the hesitation i'm seeing if your interested, the inlet manifold isn't to much of a job, I released the offside engine mount and lowered and tilted the engine on a jack (with wooden chock of course!). It's still pretty tight but not to difficult.
 
Back
Top