I did a search for this and couldn't find what I was looking for....

Those of you who have a Defi D Boost gauge, and are completely stock, where is the needle pegging to then tapering down to ? There are 3 slashes in between the 15 and 20. I figure 16.25/17.5/18.75.

My car is stock, checked all the vaccuum connections, and it will hit the middle slash then taper down to right above the "15". When I first installed it about 7 months back, it would hit the slash before the 20 then taper down. I tapped into the vaccuum line near the throttle body (that goes to the blow off valve). I also checked it today on the vaccuum line near the FPR. Same results with both.

When off, the gauge rests at "0". (someone asked me to check this). What could be wrong that is not allowing me to hit 19 then taper ? Wastegate ? Diverter valve ? Bad Gauge ?

Thanks!

 

The stock ECU makes it taper down to ~16psi after 5000rpms or so.

Mitsubishi did it this way to prevent knock/detonation.

Install an aftermarket boost controller.

 

There are several things can cause a change in boost or that you can check. First what was the outside air temp during both tests, remember lower temps cause the stock sylinoid to boost spike more. Seven months ago the outside temp was pretty cool or more often than now. Hot air is not as thick so the turbo has to work harder to spool. Second make sure all of your IC clamps are tight. Replacing with T-Bolt camps is always better but not a must unless you find that they are not holding up like they should. Several people have found leaks in the upper piping due to the stock clamps though. Reset your ECU this is always worth a shot and a very easy fix or to rule out. Make sure all of the vacume lines that run to the boost sylinoid are in good condition and not kinked or cracked and feel for the restrictor make sure it is atleast 1-2 inches down in the line and not right up against the boost sylinoid. This is just what I would check right off hand so I hope it gets your started but I think the biggest thing you are seeing is the weather change, this is what an adjustable EBC is so much better.

Hope it helps

 

It's because of the stock boost solenoid that tapers the boost down, just get an MBC and it will all be fine Bushur racing has one for 75 bucks, its the one I chose and I told 21 psi untill redline now. It makes a damn good difference.

 

Good deal. Thanks for the quick responses. I didnt take weather into consideration. It was about winter time that I installed it. Hence the reason it seemed to peg right below 20 a lot quicker and longer than now.

Thanks