Base boost,why?

[Soulboy]

Hi all,

Blasting down M25 this morning,well late lol,overtook some cars at high speed,boost guage hit 18psi(although it's only mapped to 16psi),next time I floored it the usually razor sharp throttle response had gone and it would only hit 8psi which I'm guessing is base.

I've done 100 miles since and it hasn't changed,no warning lights or messages though,fuel consumption fine,starting on the button and idling perfectly but 8psi boost

Been under the bonnet briefly,no obvious pipes off or split-tcv,one way valves and maf all new in the last 2 months,so haven't got a clue tbh

Any ideas gratefully received(btw V70 T5 2001)

TIA

[M-R-P]

Might be worth adding the car was run out of fuel recently, as I said, a blocked fuel filter might cause a problem and other's opinions on that could be useful.

Have you checked for codes yet?

[Soulboy]

No codes Martin but it is a cheapo reader )-:

[M-R-P]

Hmmm...

I was hoping for a code.

[Soulboy]

So was I tbh,but this seems abit of a strange one because I remember that when I left the motorway and pulled onto the r/about the boost was still there,it was half a mile later it played up,so maybe it had nothing to do with that slight overboost previously!

[mitchyboy01]

Hi Soulboy,

Have you got a spare TCV to try on the car?

Also check the wastegate hasn't stuck slightly open.

[Soulboy]

The tcv is 3 weeks old so hopefully that's ok,but the wastegate theory is interesting,how would I check if it's stuck open?

[expolicev70t5]

Sounds like what my explod was doing only I found I had an over boost code which put it into limp mode, as soon as I reset codes it was fine again until next time it over boosted.

[Soulboy]

Sounds like what my explod was doing only I found I had an over boost code which put it into limp mode, as soon as I reset codes it was fine again until next time it over boosted.

Well I was poodling about this morning,cheesed off the thing felt pedestrian compared to usual,got on the dual carriageway and booted it,8psi then 6 then 8 then6 and so on for a mile-then slowed and when I pulled away the throttle response was back.

So waited for the next clear long road,gave it some,and whoa 16,16,16, been like that ever since.

So now I have another question-if the actuator was jammed as suggested,would booting it at speed free it up?

If so, should I buy a new one and if so, which one should I get? (yep that's two questions lol)

[LeeT5]

Well I was poodling about this morning,cheesed off the thing felt pedestrian compared to usual,got on the dual carriageway and booted it,8psi then 6 then 8 then6 and so on for a mile-then slowed and when I pulled away the throttle response was back.

So waited for the next clear long road,gave it some,and whoa 16,16,16, been like that ever since.

So now I have another question-if the actuator was jammed as suggested,would booting it at speed free it up?

If so, should I buy a new one and if so, which one should I get? (yep that's two questions lol)

Your car WILL have logged a code, you just need a proper code reader to extract it/them.

You'll need VIDA/DICE or a BSR code reader will do it, failing that, any garage that has decent (expensive) diagnostics readers like Bosch or Snap-on etc

I wouldn't advise you buy anything for your car until you diagnose WHY it did what it did, otherwise you're just pissing in the wind my friend, throwing money at your car when you don't even know what's wrong.

[M-R-P]

Something to note, regarding the actuator jamming....

Actuators don't jam. They get weak or stop working altogether. The spigot that goes through the exhaust housing to the wastegate itself can jam or go stiff. It's a common problem with the TD04HL series, moreso on the 16t (as you have a kinagawa 19t, it's safe to assume you have the original 16t hot side).

The spigot can easily be freed - off with plusgas and copper slip sprayed through a small tube.
As you've already measured and set your actuator pressure, I doubt there's anything wrong with it.