R32 Gt-r Strange Boost Behaviour

[RyleyMA61]

Okie dokie

Now my GT-R has never felt as quick as I expected. Mods are as follows:

1990 standard GTR

Mine's ECU (rich as f**k)

3.5" catback

Standard everything else (inc airbox, dump pipes, cat etc)

107000kms

But the other day it took off like a rocket. I have since confirmed that the boost gauge tears off past 1.2kg/cm^2(!!!) and I know standard should be 0.8 bar (11.8psi)

When it isn't going berserk, it only holds about 0.5kg/cm^2... Which is well below 0.8 bar.

So this suggests to me that the boost control solenoid might be f**ked?

Any similar experiences?

Thanks,

Ryley

[Moodles2]

Mine's ECU is tuned for japanese 100ron fuel, most likely the problem is there.

1.2kg/cm^2 is 17.1psi, if that is on stock turbos you can kiss the ceramic wheels goodbye in record time, they're not meant to be boosted past 1bar (14.7psi or 1.03kg/cm^2)

[RyleyMA61]

thanks mate im aware that the mines ECU is for the 100ron fuel.

thankfully there has only been 3 or 4 spikes into that boost level, not keen to do it again. would like to just get the boost level set to standard.

does the ECU control boost?? i assumed that only the solenoid did??

[Moodles2]

ECU has nothing to do with boost, only the solenoid and the ball bearing restrictor (or lack of) in the hose control the boost. Should be seeing exactly 14.7psi without the restrictor (indicated by a yellowband on of of the hoses going to the solenoid), if you want to to lower the boost put the restrictor back in.

[Moodles2]

If you can, get your hands on a stock R32 GTR ECU, see if it still happens.. sounds like a boost leak also

[RyleyMA61]

cheers mate. afer a bit of searching last night, i hve found all the hoses/schematics i need... and i reckon you're right, a boost leak.

otherwise will check ECUs. going to go for a power FC at some stage anyway.

thanks

ryley

[femno]

Ummm...I dont understand how the problem is most likely in the Mines ECU?????

The tune on the ECU has absolutely nothing to do with the way the boost behaves in regards to max/min boost.

The excess fuel could be caused by a boost leak yes, that could also just be the tune.

What you do is:

Disconnet the line that goes to the bottom fitting of the solonoid (one that comes from the rear underneath of the collector and Ts into the actuator circuit on your schematic), and put a bolt or something in it. This will give you full actuation (lowest boost).

If you still have overboosting, its either the pressure source (split hose) or a faulty actuator or 2. You can test the actuator by blowing into the front of it, you shouldnt be able to blow air into it.

If you no longer have overboosting, the solonoid is bung, and they do pack up sometimes.

[RyleyMA61]

cheers mate that was pretty much my train of thought too.

the reason im leaning towards solenoid is it only does it a handful of times. normally it just sits on the meagre 0.5 kg/cm^2. but a couple of times i've given it the beans and it's rocketed off towards 1.2kg/cm^2.

but yes, i will try that procedure, thanks.

what are the standard wastegates on the turbos set at? ie what should it run with the bottom fitting disconnected and plugged??

[Moodles2]

Standard wastegate pressure is 10psi (well on my 32 GTR anyway)