I've fitted a remapped ecu. So today I thought I'd try upping the boost, money's a little tight this month so as an experiment I got a pair of 1mm mig welding tips to see what the difference was. Expecting 14psi. Even from the first pull I thought this doesn't feel any different, looking at the gauge I saw the normal 9psi. What the hells that all about? I don't have the stock boost solenoids anymore so I can't even go into the 7psi safety boost. I did a boost leak check last weekend in preparation and there wasn't any noticeable leaks.

 

Suggestions?

Where did you add the weld tips.

 

Have you bypassed the boost solenoids?

 

I assume you understand how the std system works?

Yeah I just have a single line running from the throttle body pipe nipple to the actuator. Which contains the stock boost jet. The 1mm boost jets are fitted in this line. I think, think, that the silicone pipe I used has a larger ID and its leaking round it, I guess it wouldn't take much of a leak to cause the issue.

Ok, I guess that's the problem

 

The stock system works by applying a vacuumed to the actuator, at 7psi or so the wast gate opens.

This line has a t in it and when in normal (not safety boost) mode the solenoid is open. This allows a bit of vacuume to be bleed off ( there is a restrictor in this line) so when the car boost to 7 psi the actuator sees 5psi and at 9 it would see 7 and open the waste gate.

 

Basically, if you just have a single line from the pipe to the actuator, you will always see 7psi. However the smaller you make the restrictor, the more of a boost spike you will see. This is bad.

 

i would suggest your simplest solution would be to fit a manual boost valve. I have been running one until I fit an ebc

 

I would recommend this one- use a ball and Spring type

 

http://www.ebay.co.uk/itm/MBC-Manual-Boost-Controller-any-Petrol-Turbo-Car-Ball-Spring-BLACK-/131623023249?hash=item1ea557f291

 

Once you get it running on 14psi be prepared for a big suprise!

have you got dump valves or leaking recircs,

if you leave pipe that goes to actuator open and block engine side so no leaks it should boost to it goes bang lol...try it open up the road but very carefully cause it will boost very high if theres no problems,

if it still boost to 9psi it could be a dump valve or recirc causing an internal leak, which is a problem i had,

 

or has you say its leaking past your restriction...

Ok, I guess that's the problem

 

The stock system works by applying a vacuumed to the actuator, at 7psi or so the wast gate opens.

This line has a t in it and when in normal (not safety boost) mode the solenoid is open. This allows a bit of vacuume to be bleed off ( there is a restrictor in this line) so when the car boost to 7 psi the actuator sees 5psi and at 9 it would see 7 and open the waste gate.

 

Basically, if you just have a single line from the pipe to the actuator, you will always see 7psi. However the smaller you make the restrictor, the more of a boost spike you will see. This is bad.

 

i would suggest your simplest solution would be to fit a manual boost valve. I have been running one until I fit an ebc

 

I would recommend this one- use a ball and Spring type

 

http://www.ebay.co.uk/itm/MBC-Manual-Boost-Controller-any-Petrol-Turbo-Car-Ball-Spring-BLACK-/131623023249?hash=item1ea557f291

 

Once you get it running on 14psi be prepared for a big suprise!

 

I thought I understood it but you've confused me now. So I need a Tee in the system? I cannot just run a single line? Why is this? I was under the impression the actuator is just a diaphragm controlled by the engines vacuum, when it sees 7psi the diaphragm is overwhelmed and opens the wastegate. I can't see how it needs more than just a vac/boost line to apply the manifold pressure :s

have you got dump valves or leaking recircs,

if you leave pipe that goes to actuator open and block engine side so no leaks it should boost to it goes bang lol...try it open up the road but very carefully cause it will boost very high if theres no problems,

if it still boost to 9psi it could be a dump valve or recirc causing an internal leak, which is a problem i had,

 

or has you say its leaking past your restriction...

 

They don't leak under boost leak testing...that's all I can say for sure. There Bailey DV26 I think.

They wont cause the leak is inside the system, mine would only make 12psi even with actuators open, one day i replaced dump valves with recircs and car hit around 20psi realised what was happening and re set boost controller.

if you disconnect the hose that runs to actuator, leave actuator side open, and block engine side take it up the road slowly put your foot down if it builds over 9 you know its your restrictors/setup if not its a leak internally or something else wrong...

https://z32.wikispaces.com/file/view/TT_Vac_BoostController.png

 

This should help Steve

I think, think I've sussed it. I've now ordered an MBC anyway so hopefully the issue will be resolved.

This link explains where I've gone wrong. You need the factory boost solenoids to use boost jets, without them they do nothing.

http://www.thumper300zx.com/z32/factory_jets/factory_jets.htm

Nice link Stephen.

 

I am currently having major loss of boost myself, so hopefully this may help me understand how everything works.

Yeah the above link describes things well. Much better than I did.

 

Stephen- when you get you mbc feel free to ask about the plumbing

Fitted the mbc today. Haven't had chance to test it though. Odd thing about it, it's got a pin hole in the side. It says in the instructions;

"Please note: the small hole on the back of the T section is essential in order for the wastegate actuator to depressurise after activation-only a negligible loss to flow occurs prior to waste gate actuator activation."

That sound odd to anyone?

The mbc is effectively a one way valve, if you boost to 12 psi for example this pressure would be trapped in the line betwee the valve and the wast gate actuators. The pin hole is there to bleed off the pressure allowing tha waste gate to close again after boosting.

 

In a perfect world. This air would be returned back into the system after the arm but in reality it will be fine.

 

Just make sure that you are taking your boost supply from the pressure outlet on the hardline after the intercooler ( block off the other side) then after the mbc. Run a t to both waste gates trying to make sure each hose is roughly equal in length.

Yeah that's exactly what I've done mate. Just looking forward to enjoying the boost now.

Great explanation of how boost controllers do their magic and how to set them up.

 

http://www.serioussolutions.com/evo/ebc.htm

 

Jeff

It all makes perfect sense now. Now I think about it I don't know why I didnt realise it before. But silly really but hey, hopefully it will help others from doing it.

All sorted. Need to test it properly Ms see what she's pushing out psi wise but it makes more than 9 now.