Evenin all...

Still pulling hair out with this,

I found a perished top hat blank on the vacuum system close to the battery, have sorted that, bypassed all of the metal pipework replacing with miners vac pipe, all solenoids, the boost sensor and now the actuator to the vgt changed with genuine parts...

And yet, however I setup the turbo I occasionally get this fluctuating boost, usually under half load to a beat of about once a second. The boost can vary between 0.4 and 1.2 at worst.

I have cybox system, no cat and the egr removed

All leaks are plugged, all the hardware bar the vac sensor t'd into the vgt line on the tb is brand new. I just don't get it

Currently have turbo setup with alot of preload on the actuator, which seems to reduce the issue slightly.

Short of a new ecu I can't see what else it could be!

Any ideas hugely appreciated!!

Right... So excessive preload didn't work, I've put it back where it all should be and half the time it's great, then I get a seemingly random fit of boost on and off to the tune of 0.5 bar. No fault codes, fuelling is fine as is vac pressure at the pump... Has no one else ever had this issue?

Have you checked the turbo actuator (and the rest of the vacuum system) for air leaks?

Quote: Heathen wrote in post #3

---

Have you checked the turbo actuator (and the rest of the vacuum system) for air leaks?

---

Sticking turbo vanes? Had to remove mine before when they were stuck with carbon. After cleaning was like a new turbo.

Quote: keyL200 wrote in post #5

---

Sticking turbo vanes? Had to remove mine before when they were stuck with carbon. After cleaning was like a new turbo.

---

I'd be thinking more along the lines of an electrical fault.

Quote: Heathen wrote in post #7

---

I'd be thinking more along the lines of an electrical fault.

---

Many years ago I had random boost issues, turned out the vanes were sticking, they are quite prone for it, some try cleaning it with mr muscle oven cleaner but if you can get the down pipe off to that you might as well try removing the casting to get at the VGT, remove it and check it. If its sticking then removing the rod and turning the spindle by hand usually shows it up it'll feel notchy or have a lot of play in it

Quote: mikeinatruck wrote in post #9

---

Many years ago I had random boost issues, turned out the vanes were sticking, they are quite prone for it, some try cleaning it with mr muscle oven cleaner but if you can get the down pipe off to that you might as well try removing the casting to get at the VGT, remove it and check it. If its sticking then removing the rod and turning the spindle by hand usually shows it up it'll feel notchy or have a lot of play in it

---