Timing varies at idle FSI AWA.

[Paul Waterfall]

Just wonder why my timing would constantly vary whilst idling, I do have the odd misfire on cylinder 3 using VCDS Lite.

The timing on VCDS varies 1 to 6 degrees BTDC and sometimes 2 or 3 degrees ATDC then suddenly jumps to 12 BTDC for a while, at 12 degree there is no misfire logging on VCDS but the engine sounds noisier towards the inlet side.

Any help would be great.

 

[Ovid]

Its the ecu adjusting timing as revs alter on tickover , quite normal.

 

[Mike.M]

If it is the 2.0 FSI then check the small chain that joins the cams as this can stretch and break which is a common problem on these engines........also being direct injection the valves gum up and turn into the shape of an ice cream cone

Had these issues on the wifes Golf Mk5 with misfires and down on power. Had the head stripped, skimmed, de-coked then rebuilt with new chains, guide, cogs etc and runs great again

 

[Paul Waterfall]

The tickover stayed at 720 rpm with the odd misfire and the timing all over the place, then jumped to 12 degrees and no misfire been logged.

Seems very odd to me.

 

[Mike.M]

Get a compression test, which is what highlighted the gummed/coked up valves on our Golf...........which then lead to a stretched chain and worn cogs due to the ECU continuously maxing out adjustments to try and keep the engine power in check

 

[Paul Waterfall]

Yes its the 2.0l FSI, the head has been done just recently, if the chain was stretched a little, wouldn't the tensioner adjust any small amounts of slack.

 

[Paul Waterfall]

Had 2 compression tests done and were good, the chain cover with N205 valve replaced as a couple of control rings had broke.

 

[Mike.M]

Yes if the tensioner was in good shape, but if it had cover about 70k miles upwards, then I would have replaced it all due to wear and tear, and also the stresses it has gone through up to that point of a head rebuild.

With a head rebuilt chaging the small cam chain and cogs is a no brainer really as they dont cost much and will put timing spot on

 

[Ovid]

watch the tickover on vcds not dash rev counter, i can guarantee no engine sits dead on any tickover, not even when brand new.