Odd 'limiter' issue

miikeeyy92 · 16 Jun 2016 at 08:55

Hi guys. So I hadnt driven my car (2.0T A3) in a few months and when I got round to having a good drive to clear the system, as soon as the engine hit ~3kRPM, it was as if it bounced off the limiter and there was a bit of a lurch.

Since then I have been creeping up to this 'barrier' which has now moved further up the scale to about 5.5kRPM.

It does happen at quite high loads so potentially a turbo issue? To me, if the turbo wasn't delivering the boost, it would just lack power, not be such a violent action? There are also no lights on my dash either.

Thanks.

iaind · 16 Jun 2016 at 09:05

Could be diverter valve or something like that. Is the check engine light on?

paradigm · 16 Jun 2016 at 09:07

Any lights come on when it happened?

miikeeyy92 · 16 Jun 2016 at 09:07

Edited the original post - there are no lights on the dash.

iaind · 16 Jun 2016 at 09:09

Worth getting a code reader on it anyway as it might be storing faults. Sounds like it's backing off boost or fueling in response to something not behaving properly. Diverter valves are pretty weak on those engines and if it wasn't working it would cause over boost, which would normally result in fuel cut.

miikeeyy92 · 16 Jun 2016 at 09:25

Thanks guys. A quick google suggests a failed DV leads to loss off power and a hissing noise. I wouldn't say that i've noticed a loss in power (until the barrier described) or this noise, may be worth changing anyway.

Dup · 16 Jun 2016 at 13:12

I had this on my MKV GTI, it was the high pressure fuel pump. Car would have full power then hit a brick wall on the revs. Think it was ~£200 + fitting at VW.

paradigm · 16 Jun 2016 at 13:44

Would make sense, could also be the fuel pressure regulator.

Thinking back I had similar on my Leon Cupra R (1.8T), that said I'm not sure mine was a sudden halt to rising revs.

miikeeyy92 · 16 Jun 2016 at 15:38

Dup said:
I had this on my MKV GTI, it was the high pressure fuel pump. Car would have full power then hit a brick wall on the revs. Think it was ~£200 + fitting at VW.

This seams more like the symptoms I'm witnessing. Still doesn't explain why the barrier has moved.

ncncore · 16 Jun 2016 at 15:56

Sounds a bit like fuel cut to me.

Could be clogged injectors and you are clearing them out as you go.

Frozennova · 16 Jun 2016 at 21:13

Sticky wastegate actuator causing over boost fuel cut?

HummuH1 · 17 Jun 2016 at 09:01

First thing I would check is the HPFP cam lobe and follower for signs of wear. Very common and should be checked regularly, very regularly. Also check the HPFP seal whilst you're at it.

iaind · 17 Jun 2016 at 09:35

Ah I forgot about the fuel cam - it's notorious on these and should really be seen as a consumable item

HummuH1 · 17 Jun 2016 at 09:43

iaind said:
Ah I forgot about the fuel cam - it's notorious on these and should really be seen as a consumable item

Indeed it is. We have to check/measure ours after every race meeting, regularly replace and that's with uprated HPFP and hardened followers.

miikeeyy92 · 17 Jun 2016 at 10:57

HummuH1 said:
First thing I would check is the HPFP cam lobe and follower for signs of wear. Very common and should be checked regularly, very regularly. Also check the HPFP seal whilst you're at it.

I'll add this to the list of things to check! - thanks.