Well to start my Evo 9, while i was driving the long way home I noticed my boost pressure was a little higher then what it was tuned at. car was tuned at 24psi putting down on the dyno at that shop 364awhp, that dyno runs high call it 340awhp. On pump gas. The boost pressure has in creased to 29psi I have not turned the boost up nor has the mechanic who tuned it. My A/F is still in proper spec, ecu is not flashing checking engine light, so no Knock sensor activating. does this happen to others as well? I guess is my question?

 

On the day that you recently noticed the higher boost reading were ambient air temperatures different than on the day that peak boost had been originally set during your tune?

 

no temps were no hotter then they were the previous week, and the nut on the manual boost controller has not moved, its still snug on the top. when it was still set at 24psi. today drving around it still putting out 29psi and the outside air temp is cooler then when i had it tuned, wish i had the tune tools to check the maf out or post a pic of them up here for u guys, guess my man concern is can the stock block handle this increase, I also am not having any fuel cut out either. is there a way to check if the boost gauge is working incorrectly?

 

has any one else had similar issues with there boost controller or gauge, are all boost gauge going be unaccountably at some point

 

BRR...

1. The temperature has not affected your boost by 5psi. I just did a writeup with all the math in the "temperature boost fluctuations" thread. You can skim through my post in there to see how much it actually changes.

2. Your boost controller should accommodate for these changes regardless.

3. My suggestion would be to contact where you got the vehicle tuned and see if they offer any suggestions.

4. If they don't have anything to say, then I would MARK on the boost controller with a sharpie or something EXACTLY where the knob is in relation to the body. Then turn the boost DOWN one full turn. See where your boost is at from there. It is possible that the spring just needed some time to catch up, and when they tuned it, it was hung up in the body (though rare) and it has just spun loose.

5. Does the car FEEL like its picked up an extra 5 pounds of boost? Was the car checked for boost leaks prior to hitting the dyno, or recently thereafter?

Also... just out of curiosity, what mods are you running?

 

manual boost controllers just plain need adjusting with changes in barometric pressure and temperature. on cool mornings i would always have to turn it down a bit to prevent overboosting. i would just turn it down to get back to your target boost.

 

Keep in mind the boost will increase with the colder nights and especially being off the dyno, there is a difference in load. You could always turn it down a couple pounds if neccessary but all sounds find and normal.

 

How could his MBC "accommodate" for changes in ambient temps?

 

Initially, when your boost was set during your tune was it set on the rollers or out on the road? In what gear was boost set?

 

Because the boost controller doesn't know what the air density or temperature is and it doesn't care. This is the same for the wastegate, which is of course part of this equation. They simply wait until the turbine reaches the desired level, and they open.

I'm leaving out tons of detail here because its after midnight... I can fill in more deets tomorrow.