sparki is the j-nipple the pressure port coming from the turbo on the compressor side?. there is 2 ports on the turbo. my set up right now is: there is a vacuum port coming from the pressure side to a t, the other vacuum hose from the wastegate to the same t. from the t all the way to the boost solenoid from the boost solenoid to the vent in the intake hose. this is how it came from the factory.

 

You can email me your rom and log a pull if you have a tactrix cable. Puredriveperformance@Gmail.com

Also the nipple is on the j pipe which is black connected turbo.

 

There is one boost pressure reference source(nipple) located on the black, sheetmetal compressor discharge tube(aka, "j-pipe") bolted to the turbocharger's compressor housing outlet. The second nipple is the one on the wastegate actuator's cannister. I think that we are on the same page now, correct? Dont forget to plug off the two hose ends on the factory boost/vacuum hose assembly which you pulled off from the nipples.

 

If you bought your evo second-hand, then the previous owner may have removed the original factory boost/vacuum hose assembly to run an aftermarket boost control setup which he removed before selling you the car. In which case he may not have reinstalled the original factory boost/vacuum hose assembly.

This original assembly as configured from the factory contains a couple specifically placed internal brass restrictor orifices without which your factory ECU/solenoid boost control setup cannot function properly. You can get the original preassembled, hose assembly complete from your Mitsu dealer's parts dept for about $20.

 

sparky actually the boost/vacuum hoses are the factory ones because there are some restricted orifices inside the hose. but, what I saw that the last owner installed a plug inside the vaccum hose going into the wastegate. so I think this was providing some restricition to WG so it created more boost. the weird thing about is that I reinstall the same plug but with a new vaccum hose bc it ripped during removal. it did not make a diffirence so I left it how it came from the factory. im afraid to brake something since I don't know if my car has been tuned. ok one more question just so I got this clear. the test you want me to run I got it how I'm suppose to route the vacuum hoses. when I go for a test run should I see a gain in boost over 0.8? this is not the stock turbo boost right! I keep thinking this is low.

 

10 from the wastegate. 8 without it found out the mad sensor was shot. I would change it out since it doesn't like shooting a code from time to time...

 

Once you have the hose routed direct from the WGA to the port on the compressor discharge pipe an you are seeing 8# on your boost gauge....the 8# is the wastegate spring pressure. An 8# level is about as low as it can get on a stock, unported, 16G equipped with a stock MHI actuator.

So your turbo is at or pretty near base spring pressure for a 16G. There can be some variance due to certain factors such as whether it's an VIII or a IX turbo(different compressor hsgs), or a JDM TME, or an RS turbo due to slight differences in turbine major and minor diameters and housing differences (9.0, 9.8, or 10.5 dual or single puck), etc.

Also, I suspect that the higher mileage turbos, tend to have more hours on the actuator spring, more heat cycles and much like suspension springs that have lost their original tension they start to sag..So, with the loss over time of spring tension and resiliency there is a tendency for the first coil to compress or ride up at lower levels of turbine inlet pressure.

But, yeah basically and in general the base spring pressure on these 16G's tends to fall within the 8-10 # range. It is a pretty wimpy spring when they are new and they become wimpier overtime on high mileage turbos. So, it is pretty safe to assume that the 8# that you are seeing is base spring pressure even without verification. To veriify you would have to adjust the actuaror rod length to where the hole on the turnbuckle freely slides on and off of the flapper valve's pivot arm.

At any rate and as a practical matter you are going to want to increase wastegate spring pressure via adjusting actuator rod length.

 

So yeah, if you have a hose routed direct between WGA and the compressor discharge nipple and you see 8-10# that is within the normal range on an unpreloaded factory MHI 16G gate. Like I mention above there are certain variable factors. But, 8-10# is normal. Your particular gate may have been at 10# when it was brand new but overtime spring tension and pressure has drooped down to its current 8# level. Also the previous owner has played around with the factory boost/vacuum hose assembly. So it is not pristine.

Like I said, the stock WGA spring, even when new is pretty wimpy. If you stop and think about it, if the flapper is full open by 8# of manifold boost pressure, this means that the flapper cracked up off its seat and started lifting much earlier. Let's just guess that the flapper valve had lifted halfway through its arc of motion by 4#. Wow, you have a turbine that is spooling waaay slow as half the exhaust energy is being bypassed before it gets a chance to see the turbine blades. Major slow spool.

So, let's adjust (increase) spring pressure aka as increasing preload.