So I recently installed a Grimmspeed 3port boost controller and then had the car dyno tuned, it was tuned with 24psi final product. I drove the car home and it held 24psi great. I decided to go for a drive later that night and it would only boost 20psi. I drove it some more today after work and it makes 24psi in 5th gear, but in 1,2,3 it only makes 20psi, 4th is about 21psi

Does anyone have any ideas of where to start?

 

I assume that your Evo IX has the stock turbo equipped with the stock actuator? Does the boost taper in 5th gear after hitting 24#?

 

oh yeah sorry, stock Evo IX, intake, TBE and Grimmspeed 3port boost controller. It hits 24lbs and holds steady in 5th.

Tuner seemed to think it was a boost leak when I asked him over the phone, but that was before i knew it hit 24lbs in 5th... I just said it's only making 20psi now when I asked him


if that was the case it wouldn't hit 24psi in 5th right?

 

I am a little bit confused. So, you'd best get your stated facts straight. In your first posting you state that your car is fitted with a Grimspeed 3-port boost controller. But, then in your next post you state that your car is fitted with a GM 3-port boost controller. So, just what are we talking about here?

Do you mean a Grimspeed manual boost controller? Or alternately, did you mean a GM 3-port boost solenoid? Please clear up this seeming contradiction.

 

I kept seeing that in posts and I thought "GM" was the abbreviation for grimmspeed, my bad. This is what I have. I guess GS is the abbreviation

http://www.grimmspeed.com/catalog/pr...roducts_id=163

I found some small leaks on the intercooler piping and I fixed those, the car then made 24psi off and on. There appears to be a leaking injector o-ring, so that's my next fix

 

Yeah, I didn't want to make you feel too bad(just kidding). But, I think that in this case the letters G.M. stand for General Motors. FWIW, I think there was a 3-port boost control solenoid(BCS) on certain turbocharged G.M. vehicles from the 1980's. For example, the trend setting '86-87 Buick Turbo Regal and Buick Grand National cars had a 3-port BCS in their boost control loop if I am not mistaken.

 

So your car is equipped with a manual boost controller(MBC)? Did you happen to install the MBC yourself? If so, then tell me where is the boost reference is being sourced from.

The boost reference port on the MBC is usually the port that is at the bottom of the boost controller's body(The top being where the adjustment knob is located). So, the reference port is the port directly opposite, or diametrically opposed to the adjustment knob. This reference port should be connected via a length of hose to either a "T" sourced into the hose that connects from the intake manifold to the divereter valve, or alternately it can be connected to the nipple on the compressor discharge tube("J"-Pipe).

The other, or side located port on the MBC is the boost signal port. This port is at 90* angles to the adjustment knob and the reference port. The signal port should be connected via a hose to the top of the wastegate actuator.

 

I don't have a MBC, just the Grimmspeed 3port. I'm going to do the injector o-rings and post back here if that fixed it.

 

Your per gear boost mapping duty cycle is not tuned correctly. I would find a tuner that doesn't block out the mapping 1 dimensionally. The proper way to tune a electronic solenoid is to have each gear have it's own duty cycle mapping. Any real pro tuner will be able to set this up correctly for you so you hit the proper boost in all gears. Mine is set up properly this way on the pier burg 3 port solenoid.

 

well what's weird is it sometimes hits 24psi in 3rd and holds strong to redline, but other times it's only 20psi. The AFR's when it hits 20psi are 10.0 which means it's a post-MAF leak

 

Maybe so, and I am not trying to be argumentative(who me?). But for sure, "proper" boost will be more difficult to achieve in 1st and 2nd gears than in the higher up forward cogs.