M35 Stagea Boost Limits To 9psi When Warm

[nomisf]

Hi All,

I was wondering if anyone knew what can cause the M35 to limit boost ?

The car runs spot on for the first 20 minutes of a drive, hitting 14psi on the gauge - however once it is properly heatsoaked, it drops to 9psi. Restarting the car cures it for about 30 seconds (so it seems electrical) then it drops off again.

I am seeing no other problems, car drives very well and is smooth and torquey - just missing power when the boost drops. There is no CEL/MIL and no stored error code. Everything on the GReddy Informeter looks normal too!

Thanks in advance

[BoostdR]

The boost valve controls this. Opens up and lets vacuum bleed off some pressure to the wastegate for it to open up later for high boost. If you re-route the line from the intake pipe around the solenoid to the tee piece it will stay high all the time. ie: join the two vac lines going into the solenoid together.

[nomisf]

Cheers BoostdR,

Even at highway speed, under full load in a high gear - I still only get 9psi.

I was going to plumb my EBC in, but I wanted to make sure this wasn't a sign of a bigger problem,

[scotty nm35]

It's in some kind of limp mode if the boost drops, either overboosting, knocking or similar I suspect. You can bypass it like Matt mentioned for 14psi constantly, it will likely work better than your EBC, especially if you try and run more boost than stock.

[BoostdR]

Interestingly I found boost cut to be right on max injector duty cycle so if your ever hitting boost cut your running the chance of running lean and knocking. The factory know what they are doing we are all just playing catch up [emoji4]

[nomisf]

I did some investigation at the weekend, in the form of a few runs down Santa Pod dragway. It seem to me, that the boost may be peaking a little high and tripping injector duty or airflow. 15.7 @ 84mph, with a drop to 8psi at the 1/8 mark. I stopped running after that as I didn't want to pop it!

The car is otherwise stock, so I suspect I may have a minor boost leak - or something the previous japanese owner has done before the import (there are signs of some previous mods).

I have fitted the EBC now, and it seems to be going well - I have an AFR gauge in place, I just need to get the exhaust done so I can fit the sensor.

Thanks for all the help