Overboosting issue
 

Ok I did search but I guess i'm just not good at the keywords to use but anyway, here is my problem

I'm using an hks standard external wastegate

When I run of the wastegate, it runs normal boost levels (off of the WG spring)
but when I tried to install a boost controller, it tends to overboost.

I tried the Apex boost control kit to my PFC and I've also tried hallman MBC

How is the wastegate supposed to be connected with an MBC? Maybe I installed it incorrectly

on the apex boost control kit, i've connected as follows:

[Intercooler piping] to [NC port of solenoid]
[COM port of solenoid] to [TOP of Wastegate nipple]
[Side of Wastegate nipple] to [Intake manifold]

Also, Is using the top nipple of the wastegate the only way to control boost? Or can I use just the side and piggyback with the MBC?

Whats your boost pattern?

Erm... He said external wastegate. I have yet to see an external wastegate on the stock twins.

EDIT: COM should go to the wastegate nipple, NC should go to the turbo compressor housing. I've heard that it's important to get it as close to the compressor as possible. I do not know why. <<That's how it is on my PRofec. It's similar on the apexi AVC-R. Links

Helps if I read it correctly next time lol. Sorry!

i can imagine you'd want the boost source to the wastegate actuator to be as close to the compressor housing if not in it, to increase the response of the actuator so it responds as quickly as the change in boost does.

Ah, yes, that's it. Also since the electronics are getting your manifold boost the solenoid doesn't need to. The solenoid should be getting compressor housing boost for the reason stated above. Pressure drop could be what's causing your overboosting since your solenoid NC is coming after the compressor.

Your NC nipple isn't after the intercooler core is it?

Thanks for the responses guys

the NC nipple is right after the turbo, (the first coupling connected to the turbo before the IC)


I will try to shorten the vacuum lines and see what happens


btw, my setup is on a single, not stock twins, sorry if i confused anyone

Make sure none of the vac lines to the solenoid and wastegate are pinched or leaking. if the wastegate doesnt get all the pressure it's supposed to be getting it will open alot later, thus making you overboost.