My Evo 9 is bone stock (35k miles) except for a Tanabe medalion exhaust and Perrin air intake.

For 10k miles +, the car has always ran great when I had the stock intake. When I installed the Perrin intake, I ran into a problem one day while driving on the highway. I was accelerating onto an on ramp and then the car felt like it wasn't getting any air. I pulled over, popped the hood and saw the coupler was disconnected on the throttle body. d'uh. I guess I didn't tighten the coupler good enough. Fixed that issue. I haven't attempted to tune the car yet either.

Now, however, I was driving in somewhat moderate level of traffic on the highway and noticed a significant amount of power loss throughout all rpm bands. Boost on the gauge doesn't surpass .6-.7 bar on WOT.

Anyone know where to start? Boost leak test? Change Spark plugs? Upgrade fuel pump? Tune the car?

 

I'd start with a boost leak test for sure

 

Thanks. I didn't do the boost leak test, instead I decided to double and triple check the clamps on the couplers. Most were somewhat loose. When I did the Perrin install, I used screw drivers rather than a socket wrench to tighten (bad mistake). Definitely not adequate enough.

I took the car out for some pulls and noticed my boost levels were back to original levels. At my shifts points, pressure maxed at : 1st gear .9/1.0 bar, 2nd gear 1.0/1.1 bar, 3rd gear 1.2 bar, 4th gear 1.3 bar, 5th gear 1.4/1.5 bar.

 

The stock clamps are garbage, my intercooler piping blew off the TB the other day, get some t-bolt clamps if ya can

 

boost leak for sure. Do a test and see what happen

 

Sounds like a b00st leak to me.

 

These cars definitely work on air man. If you have the slightest boostleak the car will limp and I mean limp running like **** until you check everything. T-bolt clamp every part of the chargepipes until there are no leaks.