Found out why my car was so slow today..........

[rockcrete]

I found out why my car is so slow today I thought it was just because I had big turbos with a stock exhaust system, but I started fooling with things. Then I came to the wastgate control solenoid (the one that has the little hose with the yellow line coming out of it - by the battery) This is basicly a bleed valve that the ECU activates this when the car is warmed up and everything is running properly, that is why removing the restrictor raises your boost, it bleeds more air off. Mine wasn't opening, even though there are no computer codes or anything, which limits your boost to around 7 PSI (if you have any computer codes, this valve will not open either) Well, I unplugged the two hoses, bridged them with a little piece of brake line I had lying around, and........ HOLY CRAP!!!!! This sucker is fast! For the first time, it feels like it would eat my old LS1 Camaro! Soon after this, I got that old familiar whiff of burnt clutch

[mcfly]

hmm by the sounds of things you removed the restrictor and got rid ofthe control selinoid all together?

if so i fear for your turbos lives.

[rockcrete]

I have steel wheeled Nismo turbos, they'll handle way more than this At least after I run a new engine management system

[CanadianGTR]

Hope you don't spike for some reason.
Wastegates are good.
It's probably better to fix the problem than just have them remain closed all of the time.

[rockcrete]

The wast gates are fine, this is just the open/closed solenoid that limits you to the high boost setting, or the low boost setting. The only reason it is there is to stop you from getting full boost when the car is cold or you have an error code in the ECU. Mine was not working, so my car was stuck in the low boost setting (approx 7 PSI) even though my restrictor was removed, bypassing means I am running at a regulated 15 PSI now. It's the same way the turbos in a 300ZX are controlled, those guys call it safety boost, and it happens all the time. It's unusual for the solenoid to be a problem, but I checked mine as per the service manual, and the resistance is out of spec. The only caution I need to show, is not to boost when the car is cold, which I don't anyway.

[CanadianGTR]

Oooooooh okay.
For some odd reason I interpreted it as you simply disabling the wastegates.

[minispeed]

This sounds very dangerous!!!!!

I don't hold myself up to be the expert of turbos/boost, but from my understanding of the system it is not the computer that switches from any hot/cold high/low boost but the job is up to the solonoid itself. At normal running before max psi the solonoid will bleed off the pressure, when you hit the set pressure that the solonoid is set at it will send the pressure to the wastegates to let the exhaust gas by pass the turbo and not spin faster and thus not create too much boost. If you by pass the solonoid then you will never open the wastegates and will then in theory create as much boost from the turbos as your BOV is set to. And for example if you went to downgear from 5th to 4th and accidently hit 2nd and the revs shot up super fast I could see this doing some serious damage and overboosting.

I clipped this diagram from the manual. The solonoid is right under the cut away of the engine (a single piston). You may have to save it and expand it to see. You can follow the flow and if you by passed this solonoid you would know that air will always travel where it has the least restriction, it would never go and travel up to the waste gate if it can flow freely back into the intake (pre turbo ie under negative pressure and not under boost).



I would welcome all input from anyone with lots of experience on this, as again I don't want to present myelf as an expert. But I think this sounds really dangerous

http://www.cardomain.com/ride/2488646/4

note the right turbo "swing valve" or wastegate shows a better example of how it allows the exahust gas to bypass, the left one looks like someone left out a line

[rockcrete]

It's just a factory bleed that instead of venting to atmosphere vents the pressure back into the intake system. The solenoid is either open or closed, nothing in between, the restrictor in the line limits how much air it normally bleeds, removing it, allows it to bleed more air. My car now holds a very stable 15 PSI.

[minispeed]

OK if it's that simple, without the solonoid how do your wastegates open fully?

You even said so yourself, this is either open or cloesed to limit your boost. If your line is always open then you have no way to close it and thus limit your turbos from creating more boost.

[rockcrete]

This solenoid has nothing to do with the wastegate working or not. This system, to put it simply, is a manual boost control with an electric on/off switch that is controlled by the ecu. When it is off, the wastegates open at around 7 PSI. When it is on, the wastegates open at 10 or 15 PSI depending on if you have your restrictor in the line or not.

Without going and looking it up, I think this is the same system used on the R33 GTS25T that has the added parameter of restricting boost in first gear. All those guys bypass them too.