Actuator or Pump?

[Jenkosowls]

T25 is all on now with no leaks put im struggling top end with the boost bouncing around iv pretty much narrowed it down to the actuator being pushed open by the waste gate as pressure builds up

Car Spec is
bosch 9mm pump
Gov solid
Lda pin
lda spring adjustesd
T25 turbo

Baisically when boost gets to around 20psi at 4k it bounces back to 10 then upto 20 before settling down at 10psi when in 5th gear it will keep bouncing up and down in pressure

Here is a poor video but you get a rough idea


Or is my pump struggling to supply the demand?

[d-jimbo]

mine does something similar. not as bouncy but cant get boost over ~22psi with almost identical setup. im pretty sure its the wastegate opening due to exhaust manifold pressure. i think i'm gonna try opening the boost actuator and sticking a stiffer spring in. are u using mbc?

[Dave]

Probably wastegate, get it welded shut!

[Jenkosowls]

was thinking more than likely wastegate opening up! its on a mbc atm but thats screwed right down effectively not controlling it as it was previously set at 25psi but wasnt boosting till past 15psi and doing same as above

[strictly_perv]

This is what you need....

[Jenkosowls]

Yes it will be done although more than likely on the arm as im not cutting elbow off again to weld inside! should be ok id guess

[n0v0s]

I can't quite make out from my phone... but, that seems to be fluctuating quite quickly even though you don't lift off? .. surely if the wastegate is creeping open then the exhaust pressure/actuator opening will equalise - maintaining an equal 'boost' value on your gauge after its initial drop...

I.E .. Mine used to pin the gauge and hold over 36psi easy in 5th... then the actuator weakend over time meaning, boost would hit like 26psi peak then drop towards a maintained 10psi as the revs increased (due to wastegate creeping to its most 'open' position - as exhaust pressures rise with revs)

If its fluctuating as i think it is (might be seeing it wrong on my shitty phone..) then its a fuel problem, non? Starvation/cavitation?

[Jenkosowls]

it is fluctuating quite bad poor video mind i did think fuel starvation changed filter it was dirty but made no difference il try get hold off a better video

[n0v0s]

Are you on dino or veg oil?

Also, have you checked the in tank gauze?

[Jenkosowls]

have previously ran veg but been on derv 3 weeks or so now every time iv had gauze filter out its been clear. (use to pour veg in through this way.) boost was always fine on k14 that was 25psi+ just since the T25. if its not the wastegate i can only point it to being the 9mm pump?!

[n0v0s]

Ahhh, i overlooked the fact you have just put on a t25, and if it was fueling fine before, mmh..

Thinking about it though, if its a fueling problem then check your smoke levels out back (not exactly easy, i know..) .. if its starvation causing the boost to fluctuate, then the smoke will decrease as boost drops. In comparison to the smoke increasing if its a wastegate (hence decreased airflow) problem?

[mark_airey]

Yes it will be done although more than likely on the arm as im not cutting elbow off again to weld inside! should be ok id guess

mine is welded round the arm, just weld it with the actuator on and then bin the actuator

[Jenkosowls]

will do the actuator is fully wound back already so sealed atm hoping this solves it!

Sure iv seen others run bigger turbos on 9mm before?

[strictly_perv]

Me and mark are on 9mm pumps. I've also just fitted a larger turbo to mine and havnt had an issue like yours so it must be the gate

[Jenkosowls]

it is the actuator running de waste gated via a cable tie now haha!