I had both boost solenoids removed, car runs fine but slow. I installed a boost gauge and the reading is 6-7psi at 4000 rpm...once it spiked up to 9 at 5500 rpm..definitely not good. I think the turbos are presently controlled by waste gate spring pressure only hence the low reading =safety boost? Am I correct? Or am I missing something? I am installing a mbc (Turbo smart)..to fix this. I am reading that there are factory restrictors already fitted in the original set up..anyone have any clue about this? If so they would not work in the present situation without the solenoid fitted anyway and would have to be removed if a mbc is fitted. Maybe someone who has done all this before can enlighten me on this?? Many thanks guys
You are correct...... without the boost solenoids, the boost is limited to wastegate spring pressure (safety boost)...... once you fit an EBC you'll be able to increase boost pressure to whatever level you desire
Hmm maybe not whatever but yeah 100% over spring pressure with the Turbosmart MBC he described, and better response too
Well, I did a boost leak test and found a big leak ..the large intake hose RHS connecting the inter cooler hard pipe and the throttle body has a large tear where the hose clamp is, looks like the hose has been forced on the spigot and crimped and tore the rubber, of course underneath where its impossible to see. So I am looking for a replacement hose, Any one wrecking a tt? Brisbane area. At least I found out why I am getting safety boost.. Cheers
Yes there are small "boost jets" in the factory pipe to the wastegate. These are just a flow restrictor to help with the wastegate control. Some people replace these with mig welding tips to set the boost level higher, personally I use a MBC with the solenoids removed. I also removed the factory boost jets.
Which end are the factory restrictors located? Down near the turbo waste gates? I did install MBC today and couldn't see any restrictors topsides when I took off the small waste gate hoses ( from under the Metal boost pipes) Anyway I also did a boost leak test and I found the RHS boost hose has a large tear and is leaking badly, anyway, that's easily fixed. Cheers Eric
Don't worry about the stock boost restrictors, once the boost solenoids are disconnected from 12v the restrictors are irrelevant. Theres one per side in the tiny hose from the solenoid to the wastegate actuator. Unless the engine is out don't bother trying to change them as the drivers side is impossible with the engine in. Once you have a mbc/ebc the restrictors become redundant. Pressure is pressure and the actuator wont see any with a good ebc. The factory setup uses the restrictor to bleed off pressure which is calibrated with the stock boost solenoids.
Thank u for ur input..Seems to me whoever worked on my car and did all the usual deletes might have mixed up some vacuum hose location. The solenoids are gone and there are no restrictors in the Waste gate vacuum hoses. I am getting frustrated so I started to check what goes where..or should I noticed that the vacuum hoses from the turbo waste gate actuators are connected to the balance tube ??? I would think these 2 hoses should go directly to the T connector on to the MBC and not to the balance tube. Just to clarify the stock set up The metal boost pipes (50mm dia LHS and RHS feeding into the throttle body) have each a 6mm hose attached at a barb underneath, they in turn connect to a 6mm metal tube going where?? I guess to the waste gates? Stock configuration I mean. I couldn't quite trace these small tubes, too much in the way. I try to find a vacuum diagram .. U have any thoughts on that? Cheers Eric
