epic boost problem (20psi+!!!)

[streatracer]

I have yet to see one of the cheap ebay 16G knock off turbo's last more than 1000kms (See my signature, I have helped people removed two if these which were stuffed within a couple a hundred kms), let alone 100 000kms that a genuine Mitsi one will.

If you are going to sell it, whack a standard 14b dump pipe on it, return the boost down to 12psi or so and you won't have the creep problems.

Yes I completely agree that a standard mitsi turbo is ideal but its just too much cash for me to fork out

I'm not sure you fully understand the problem I'm having.
I can't turn the boost down because
I havn't turned it up haha I dont run a boost controller (although I do wish it where that simple) I would have thought retrofitting a more restrictive dump would make it worse????

 

[rob323]

I'm not sure you fully understand the problem I'm having.
I can't turn the boost down because
I havn't turned it up haha I dont run a boost controller

I do understand the problem. It is overboosting. Putting an external gate on it may fix the symptom, but not the cause of the problem.

You said originally that it's running 0.7 bar up to 4000 rpm, that's 10 psi, so you must still have the stock vr4 boost controller on it (little solenoid valve on the front of the stock air can). The wastegate actuator is set at around 7psi so if you take a vacuum line straight from the intercooler piping to the wastegate actuator, you should get a solid 0.5 bar of boost. If it is still spiking then have you done/ checked the following?

unless the actuator is not opening fully due to the screamer mods restricting it.

also gonna test the actuator (apparently it's common for them to fail?)

old/split vacuum lines or, like me fit them the wrong way around

Id be looking at other things first like vacuum lines as mentioned. Or actuator stuffed.

A quick way to rule this out... Run a fresh piece of vacuum line from the intercooler pipe strait to the wastegate actuator. And block up the other lines you disconnect to do this with a screw.

If its only running minimum gate pressure it'll be 7-8psi, no higher.

If it still over boosts id look at the actuator being stuffed. Or at least you have eliminated this one thing. And the boys can help you further.

I'm heading out to buy new vacuum line soon. gonna replace all boost related lines and tidy up a bit. will be running separate lines to actuator and bov etc so I don't have to run any T fittings.

yep, was going to say the same. Sounds to me like the wastegate actuator is not receiving the set pressure, and hence the wastegate is not opening up

If you have an air compressor, wind the regulator down to 10-15 psi and pressurise a vacuum line going to the actuator, make sure it opens and closes properly and you can't hear any leaks. At a guess, the rod would probably move about 15mm.