What Is The Purpose Of The Stock Boost Control Solenoid

[rtune]

In a stock R34 GTR the ECU, above 2400 rpm, sends duty pulses to a

boost control solenoid near the left strut tower. What is the ECU doing?

does it have a plan that is independent of where the stock actuator springs

open, and if so what is that plan?

[MYRB30]

My understanding is the ECU looks at air flow (through the AFMs) and compares it to rpm, if its lower than expected keeps the waste gate shut, if its higher than expected opens the waste gate to reduce turbo speed, hence lower air flow. The ecu doesn't really worry about 'Boost', it worries about air flow

[rtune]

My understanding is the ECU looks at air flow (through the AFMs) and compares it to rpm, if its lower than expected keeps the waste gate shut, if its higher than expected opens the waste gate to reduce turbo speed, hence lower air flow. The ecu doesn't really worry about 'Boost', it worries about air flow

ah, so a japanese plug-in ECU such as a Mines, or a nismo, or whatever, might know an engine has better

breathing so allowing more air to flow at each RPM point (this indirectly showing up as higher PSI than

a stock car shows).

Therefore if this boost control solenoid was deactivated, as should happen when installing an EBC,

default boost can revert to simple actuator spring rating, and if the actuator spring rating is lower

than the ECU indirectly wants, well, the stable PSI goes down from the "norm"?

have I got that all straight?

[STATUS]

the R34 GTT is pretty smart it uses a variety of things to monitor / control boost (AFM voltage, boost sensor and boost solenoid)

some of the jap remaps do control the boost solenoid.

the factory actuator is very average on GTT's and is a prime candidate for a hks or garret upgrade unit.

Edited January 7, 2009 by URAS

[heller44]

Isn't the question about r34 gtr set ups though?

I thought the boost control solenoid was to allow a drop to a lower boost level in the event of a fault.. with just actuator on my stockers 32 setup, no boost solenoid in the circuit though - totally removed, the stock boost level was ~6psi.. This had been quoted to me as a failsafe level that the ecu drops to in the event of a fault.

[rtune]

Isn't the question about r34 gtr set ups though?

I thought the boost control solenoid was to allow a drop to a lower boost level in the event of a fault.. with just actuator on my stockers 32 setup, no boost solenoid in the circuit though - totally removed, the stock boost level was ~6psi.. This had been quoted to me as a failsafe level that the ecu drops to in the event of a fault.

yeah, I was hoping URAS would chime in he is the man on these subjects, but this is indeed GTR, not GTT

and the current ecu is a nismo R1 ecu, not the stock ecu. But the rest of the system is stock.

as the car came to me, setup by nismo, it was boosting to 1.3 bar. But the wg actuator springs

are not rated that high of course. Now that I think the stock solenoid has been disconnected for

the hks ebc, baseline boost is much lower. So I was trying to figure out what the ecu was doing.

[STATUS]

yeah, I was hoping URAS would chime in he is the man on these subjects, but this is indeed GTR, not GTT

and the current ecu is a nismo R1 ecu, not the stock ecu. But the rest of the system is stock.

as the car came to me, setup by nismo, it was boosting to 1.3 bar. But the wg actuator springs

are not rated that high of course. Now that I think the stock solenoid has been disconnected for

the hks ebc, baseline boost is much lower. So I was trying to figure out what the ecu was doing.

sorry my bad (i get hit in the head alot)

the ecu is not controlling boost if it has the HKS ebc hooked up, the ecu monitors boost and regulates it via the solenoid, in your case it is ignoring the factory solenoid.

i have only ever had one remapped ecu control boost well and it was a mines remap that ran 1.2bar on the nose from start to redline (as good as any aftermarket ebc). i know Nistune is working on getting it working via the std solenoid but it is a matter of finding the correct address.

have you had it on a dyno? to see if it is indeed tuned for 1.3 or has someone just fitted a boost controller?

Edited January 7, 2009 by URAS

[rtune]

sorry my bad (i get hit in the head alot)

the ecu is not controlling boost if it has the HKS ebc hooked up, the ecu monitors boost and regulates it via the solenoid, in your case it is ignoring the factory solenoid.

i have only ever had one remapped ecu control boost well and it was a mines remap that ran 1.2bar on the nose from start to redline (as good as any aftermarket ebc). i know Nistune is working on getting it working via the std solenoid but it is a matter of finding the correct address.

have you had it on a dyno? to see if it is indeed tuned for 1.3 or has someone just fitted a boost controller?

no boost controller when I got it, definitely. omori factory, as it came.

It is advertised as 450ps / 48kg torque at crank and appears to hit that on the head on the croydon dyno, with pretty good AFR

but as you say I don't think boost was controlled flat: from memory it would hit 1.3 and be at 1.1 at the end.

The ecu docs (in japanese) say something about 1.1 as well -- see attached. (you guys with japanese connections, a translation of this

would be wonderful !)

Now the factory solenoid is not connected, the HKS can hold at ~12psi flat (0.82 bar).. which was what I was trying to understand,

and it sounds like the factory wastegate control solenoid was seeing action.