My evo seems to lose boost no matter what I try, it hits 23PSI and then tapers down to 17 by 7500. I know I could lose maybe 1-2 PSI from peak to readline on my 03 but the 06 seems to taper a lot more. Is there something in the ECU that I need to change or is the ECU even doing anything with boost now that I have a MBC? What I am looking to do is keep the boost from dropping like it is now. The Mods I have are

TBE no cat
MBC

 

Replace your stock turbo wastegate actuator.

 

Has the car been flashed at all? There is programmed taper in the boost map...do some research and you will see how to fix it. IF that has been done, yeah its gonna need a stiffer actuator and then mapped according to it.

 

He's running a MBC.

 

The reason that your having more taper is the MIVEC.

The MIVEC on the IXs lead to more taper at high RPM.

 

So even if he replaces his wastegate actuator he'll still taper heavily due to the MIVEC? Could this be addressed by a reflash that adjusts the MIVEC?

 

Really, why? I have a IX MR and its 100% stock, I know every stock car is a little different but I lose like .1 bar max from full boost to redline. It will drop from 1.4 to 1.3 maybe 1.2 something.

 

You mean because MIVEC gives a higher volumetric efficiency, then the airflow goes up so with the turbo on its limit the boost goes down?

Maybe I could get a bit more at the top, but my programmed taper is 1.65kg/cm^2 at 5000 dropping 0.05 per 500 RPM thereafter to reach 1.40 at 7500 and it will pretty much hit these in 3rd gear, comfortably in 4th gear up.

Will the 8 run a lot more?

 

If he replaces his wastegate actuator, it might help.

Also, there may be a way to tune the MIVEC to help get rid of the taper too, but I havent seen anything bout how to do it.

Its just known that IXs taper more then VIIIs and that it is due to the MIVEC.

 

You need a WORKS P2 brain flash.
WORKS was the very first EVO tuner in the U.S. to reflash the factory ECU. Our Software Engineers have been disassembling US-Spec EVO VIII code since April '03 and have software control unparalleled in the industry. Nothing comes close to the plug-and-play performance and reliability of the WORKS Brain Flash series.

The Brain Flash P2 represents an upgrade to the Brain Flash P1 by increasing and holding the factory peak boost level. This WORKS flash is very unique in that NO other flash on the market can properly control boost internally through the factory ECU! The P2 provides addictive acceleration by eliminating the factory boost taper in the higher RPMs. By eliminating this boost drop-off, the total area under the torque and horsepower curve is enhanced and the car responds with increased urgency as the power band winds up.
WORKS' Engineers spent many months analyzing the stock boost control system. Then improved upon the factory design to bring you a true peak and hold system. There is no bypassing the wastegate solenoid with a questionable bleeder/emulator, no attempt at fooling the ECU logic and no manual boost controller (that can change with weather and taper boost) nor electronic boost controller is necessary! This proprietary system represents a tried and true, reliable design that takes the safe factory system one step further. With the unique WORKS Boost Hose Assembly (which appears identical to stock), we are able to modify the wastegate solenoid ECU maps. WORKS has total boost control. We can raise, lower, make a sine wave, or even have the boost taper upwards all through the factory ECU! Of course the P2 upgrade involves a comprehensive performance ECU remapping of the air/fuel ratios and ignition timing to compliment the rock-solid peak boost. Expect peak gains in the mid 20s with total area under the power curve increasing by 10%-20%. US-Spec EVOs do not have a top speed limiter to remove but we have raised the RPM limit to 7800 and the P2R version available in the WRP (WORKS Racing Program) raises the launch control RPM limit at no extra charge.

The ECU can be reprogrammed back to stock if necessary and, of course, is backed by our Factory-Matched Warranty.

*Custom tuning is also available. From just one gear at Wide Open Throttle all the way to multiple gears at various throttle positions. Please call for details.

Application: '98-'06 EVO V/VI/VII/VIII/IX including RS and MR. Please download and complete the Brain Flash Checklist when ordering.

 

 

Ok so on my IX I have experienced the same taper with the MBC and the ECU....I am back to ECU controlling boost and cannot wait to see it hold better than it is right now....In 3rd gear I spike at ~22.5 and then drop to like 17 / 18psi by ~7200....The same thinh happened with my MBC, so I believe it to be the WGA or Turbo rather than the ECU....

 

^^
LISTEN

FACT 1 - the is no way to get rid of taper all the way

FACT 2 - IXs taper more then VIIIs

He does NOT need the WORKS flash. The WORKS flash doesnt get rid of taper like they advertise. THere is no way to complete get rid of taper.

The best idea would be a WG actuator.

 

It looks like I hit a wall and I am not the only one. I wish someone would find a way to control the taper. I know there has to be a way just no one has found it yet. Has anyone does the wastegate deal yet and if so what were the results? Also I have ran a dynoflash and a Vishnu map and they both taper about the same.

 

I thought the same thing until I put it on a dyno and you can see the taper. It's hard to look at a boost gauge going WOT in 3rd at 7000 rpms.