Multiple Misfire on 24v - help

[cos140 0]

Hi all,

My good ole 2002 V6 has developed a problem :-(

Basically, my Service warning came on a few days ago saying service in 2000 miles so fair enough. I got some oil and a filter and decided to do it yesterday.

I had some stuff in the back of the car that needed putting round the back of the house so I decided to start up the engine to get it warmed up ready to change the oil. Everything was fine and was ticking over for about 5 mins. I had to move some stuff in the garden so decided to turn the car off just in case some bugger punches it!

I went back to it about 15 mins later to simply turn the car around to do the oil. It started but was lumpy and misfiring. So gave it s couple of blips on the throttle incase it choked up but still the same. Next thing the EML comes on!!

I decided to do the oil anyway as it wont harm it. Started it up after and yes its still the same. I took it for a spin and it actually runs ok(not 100%) and still has most of its power. At low revs or tickover its a pig and just misfires like hell.

Ive plugged in a code reader and it said Multiple misfire detected, camshaft sensor bank 1, camshaft sensor bank 2 and also crankshaft sensor!

We cleared them all and tried again and they all came up again except the cam sensors.

Ive still got my old V6 so I decided to swap a few parts over.

Ok, ive tried the following items and each time tried it:

Spark plugs

Coil packs

Cam sensor 1

Cam sensor 1

Cranksensor

MAF sensor(just in case)

Removed the timing chain tensioner bolt just in case it had stuck. All ok

Also done a compression test and all were roughly the same.

Ive read that it could be timing chain related but its only just done 108k miles. My other one had done 272k miles and that just started to rattle

Sometimes when its ticking over you can hear a chuffing noise which sounds like the compression is leaking somewhere, maybe out of the inlet valves??

As I have done a compression test this surely would rule out valves and pistons?

Anyone got any ideas or pointers as to where i should start looking?

Hope you can assist,

Thank you all

Justin

[cos140 0]

I have since done another compression test and the results were interesting to say the least.

All were at 250psi except no5 cylinder. That was at 140.

Reset it, tried again - 160, again 220. Then it stayed at 220 each time i try it.

Didgy lifter or oil pressure??

[cos140 0]

Quiet this forum ..

[Therusterman 59]

Have you considered doing a leak down test? Might pinpoint the problem if you've tried everything 'outside' of the engine.

[cos140 0]

Ok, I found the problem after searching through various forums on the net.

Im surprised that the answer wasn't on here to be honest as this is dedicated to the VR6.

Basically the VVT control valve was jammed open by a burst steel mesh, the mesh designed to filter the oil but they fail prematurely, usually when engine is cold.

[Therusterman 59]

The vr6 (AAA) doesn't have variable valve timing, so its not a problem we'd see. Glad you got it sorted though 

[cos140 0]

Aha, that would explain it :-)

So is this forum only for the earlier AAA and not the later AYL engine?

[Therusterman 59]

I'd say generally it is yes, catering for the golf/vento/corrado vr6. The AAA shares some similarities with the AYL and subsequent 6 cylinder engines, but some of the biggest differences occur with the cylinder head to accommodate more valves, variable intake runners etc and other changes to comply with emission regulations.

 

I'd say you may find more specific info for your engine on a mk4 golf forum as that car and models which share the same platform would of been fitted with the AYL engine.   

[craggsy 91]

R32OC might of known this as they know about VVT problems

[himselfunknown 4]

Cos140 - I'm having the same trouble with my V6, although mine is the AUE engine code. Is there any chance you can give more detail and/or point me in the direction of a forum/thread where you got your info please?

 

Craggsy, in addition to your point about the R32 VVT - the VVT on the R32 is different to the 2.8, I'm told. The 2.8 is an on/off thing operated on the timing chain to help with emissions when cold, the R32 has 'true' VVT.

 

Probably not helpful to the thread in general, but I'm trying to track down issues with my Golf at the mo and I'm finding the internet is a jigsaw of information - a piece at a time it's no use but each time a piece is joined up it makes more sense!