Hey guys I have a problem an not to sure what it is. So When I drive my Evo ix it boost weird. Say I I launch It only boost up to 14-15lb when I'm set to 22lb then switching to 2nd it boost to 15-16, 3rd 21-22, 4th 22, then 5th goes over to 23-24. These are not exact boost reading there just rough reading for you to understand what its doing, an it never did this before. So wondering if that's my wastegate or MBC or just something else. I have Hallman MBC installed a new one about 30k miles, stock turbo and wastegate. So any advice or ideas would be great thanks for the help evom

 

Typically you wont hit full boost til 3rd and in 5th it might overboost or creep because the flow of the engine exceeds the flow of the wastegate and it increases boost a bit. Been a long time since i ran a stock turbo so not sure if the number are exact. But it tends to be low in 1-2gears

 

That's weird cuz it never dont this before if it boost lower 1st-2nd it wasn't by this much an every gear after were exact on 22lb. But that's normal then great lol.

 

if you want a little help you could change out that boost controller. according to this its one of the worst out there.
https://www.evolutionm.net/forums/ev...ed-tuning.html

 

Boost leak?

 

^Not a boost leak. I checked that

 

Wow that good info, thanks

 

Find someone close to you with a different MBC, then post results.

 

I think that Joseph is right. The IX turbo is a relatively fast spooler. But, in the lower gears the engine pulls through the turbo. Your turbo's rate of spool is not directly proportional to engine RPM in the same way that a supercharger is.

Like joseph says, you probably have too little preload so your turbo is spooling slow. Whereas in the higher gears it is creeping.

 

Cool! Thanks everyone for the help just making sure because it didn't do that before. But thank for the answers

 

You have a 5-spd tranny right? It is best to set peak boost level in 4th gear at WOT. Ideally, either 4th, or 5th. But, as a practical matter, in 5th @ WOT , you reach too high a road speed on public streets at full song. A long uphill strech of road in 4th is good.

 

Are you running the factory black rubber inlet hose between the MAF sensor and the turbo's compressor inlet? If so, did you plug off the nipple located on that inlet hose that serves as the return from the boost solenoid?

 

Hmmmm. Try this: rotate the adjusment knob on your MBC all the way ou counterclockwise to the lowest possible boost setting(-). Take the car gor a WOT run and tell me what the boost level reading is on your boost gauge. Also, take note of whether it creeps with the MBC adjusted this way.

 

As an option you could go 3-port and set target boost for each gear if you wanted. As for your boost levels fluctuating,you should make sure you have correct waste-gate pre-load. After that I would check for any boost leaks again and then make sure your MBC is functioning as it is supposed to. But as others have said, you wont hit the same boost in each gear. usually goes up with gears. This is also affected by weather outside, so you will see changes from day to night if its drastic enough.

 

All of the above are good suggestions. Incidentally, OP, did you actually conduct a thorough boost leak test, or did you merely do a visual check?

The little detail about the boost getting higher(approx. +1 PSI per 10* F drop in ambient air temp) is true and is most noticeable in the higher gears. You always have to keep this phenomenon in mind if you sre controlling boost with an MBC. The ambient air temp swings are a non-issue with an EBC, and ECU boost controllers. This is the price we pay for running our relatively cheap and unsophisticated Manual BC's.

For troubleshooting putposes it would be useful to disconnect the MBC and run the gate direct off the compressor discharge nipple. Determine base wastegate pressure first by loosening the actuator rod's turnbuckle and determine if boost creeps even at this low, base boost level.

You could always swap in a known good MBC.