HOWTO: RB25DET High Boost mode with standard solenoid

[Sciby]

Just do it.

I found it's actually safer, especially if you're fiddled and the second stage is up to 10psi... going from 5 to 10 is disconcerting, and if you're in heavy traffic, and you're just on that threshold, it's somewhat dangerous... I'm very happy... full 10psi by 3k rpm or so, solid, smooth all the way through.

[benl1981]

I just did it. But the ! (check engine..I think) is displayed on the dash when I start the car.

How do you reset the ECU? SHould this fix it? I'm searching here, and I have the service manual in pdf but can't find it at the moment.

Any Help..?

Thanks

[Sciby]

Reset the computer by disconnecting the battery, put the brake pedal few times (to ensure there's no residual charge), then reconnect the battery. Good idea to take it for a good drive now, so it remaps itself properly. Do a search or look in the DIY section for a good thread on the subject.

However, I doubt it'll make the (!) light go away. It's probably freaking out because it's no longer got a signal to the solenoid. *shrug*

[benl1981]

ummm - I am dumb. That was the handbrake light right? Well it went away when I took the handbrake off!!!

Took it for a drive. Very nice. cheap (i.e no cost) no fuss mod.

Boost used to go to the half on that +7 gauge then increase a little at 4500rpm. Now I think from around 2500-3000rpm it has that boost. Can feel that it is a bit more responsive. Only reved it to about 4-4.5k as I didn't get a chance to warm it up that much...

[Sciby]

I wondered about that... I thought you may have some strange dash, or different to mine. *shrugs* Me dumb too. :drooling:

Well, +7 = 1 bar = 14.7psi, so you're getting about 7-7.5psi... it'll feel much smoother once it's at full boost, although going from 5 to 7psi won't be too much of a jolt to begin with.

[paulr33]

hey guys,

good to hear the free mod is having success. i remember the night i thought of this crazy hack and tried it one night on the backstreets, worked just as expected. a bit more beef in the lower gears, no more waiting for 4500rpm. first gear and second gear seemed to have gained the most "stick" in the lower rpm, definetly a lot better especially for free

[benl1981]

Yeah Paul. Worthwhile little mode. I have full boost from about 2400rpm.

Are you sure about the standard 5psi then 7-8 after the 4500rpm.

My car used to sit half way on the factory boost gauge (apparently thios is about 7psi) then jump up a little after 4500rpm. (Now it does it from 2400rpm )

There is no bleed on the wastegate line so should be all standard. Has a POD filter but thats it - and cat back exhaust...

Is this normal????

Paul - you were clever to think of this mod

[paulr33]

yeah mine gets 7psi by 2500rpm (series 2)

yeah the stock r33 boost is 5psi until 4500rpm, then at 4500rpm the ecu actives a ground which opens the solenoid, basically you bypass the dynamic ground (as in only active over 4500rpm) and ground it all the time, so the solenoid is open all the time.

mine is standard, no bleed valve or wastegate or anything else modified.

Mine has a pod filter and stock standard exhaust still

[r33gtst196]

I did this mod (Black wire from solenoid to ground and it works sick boots hits 7-8 PSI at 3000RPM instead of 4500 could be fun in the wet

Also I have a fuel air gauge and there is no sign of lean out after doing this mod

If any one is interested pm me and I will look up info on tapping into the wire at the computer to Make it easy to put in a switch in the car

[MrSkylineRB30ET]

Can I suggest cutting the wire, running the device to constant earth and running the ecu end to something that has the same resistance, so that the circuit is still complete for the ecu, but the other thing thinks its above 4500?

[MrSkylineRB30ET]

Also get rid of the restrictive gause either side of the AFM, again, what is it going to stop other than air? If something is big enough to break thru the air filter, it deserves to break your afm and will regardless...

[cooky2511]

by doing this mod , will it effect the running of my power fc (which i havent installed yet)?

[ATTN]

awesome

i did it today b ut with no switch planning to buy the turbo luach swith

boost kicks in on low RPM and more torque down low

good way to give a lil boost to your car

thumbs up matey thanks for the DIY

[ecl]

has anyone done this mod for an r34?

is the ground black or white for the r34?

Thanks

Eric

[cooks44]

Trying it at the moment (didn't want to rewire my car out the front of work - changing vac hoses around is much easier!)

Mine is totally stock, save for a cat-back zorst and K&N panel. I figured if the solenoid is just opening at 4500rpm, bypassing the solenoid but connecting the vac hoses should have the same effect....

Not quite. There must be some kind of restriction in the solenoid itself that prevents boost spikes. Mine is definately on high boost all the time now, but not happily. I'm only going by the stock gauge, but by my conversion calcs the boost spikes can easily reach stock turbo destruction pressure (ie. 12+ psi).

If I gently(ish) give it more power it's pretty happy, and bloody fast! If I don't watch it and get a boost spike, the stock BOV goes off and dumps the boost pressure whilst the ECU is still delivering heaps of fuel = big backfire.

Still playing with it that way (cos' it's fun!) but not planning to leave it like that, I would end up destroying something and you also miss out on your big launches cos' you have to bring the boost on slowly. Will put the switch in on the w/end most likely, so I'll check in and let you guys know the difference.

One question, does anyone know how long the solenoid will last? The solenoid would normally only be on for a few seconds (if you're revving the engine through it's range past 4500 to 7000 before gear change) to maybe minutes (track work or maybe fast outback twisties where you're keeping the revs up and the car on boost). I'm worried if I took my car on a long (5+ hr) journey that the solenoid could burn out from being constantly on. Any comments? I've been thinking about including the idle switch in the circuit, to turn the solenoid off when sitting at traffic lights, etc.

Hmmmm... as far as I'm aware, the 33 was supposed to be 10psi max as well. *shrugs* It works, so I no complain.

Also, I believe mine is totally stock. The car was not really fiddled with when I got it. Only got mags, suspension and cat-back... no real power upgrades to speak of, so it'd be a wee bit weird if they changed the actuator spring... *scratches head*

Anyone with a definitely stock 33 turbo want to remove the solenoid from the picture and see what happens?

[Mud]

yeah whack a switch in to help save fuel ecconomy while driving ong distances

[Topkart R33]

I also thought the solenoid would burn out but i've had this mod for about 8 months now with no problems whatsoever. It's actually good for long trips as the xtra boost allows u to get up those hills without planting the throttle. I got approx 700ks when travelling to Queensland just recently with the mod in use.

[mitchy_]

im guessing my microtech LT-12 ECU already leaves it open... or something.

also the hose from the top of the solenoid to the T piece in the tube going to the throttle body piping has been plugged off, but the bottom hose on the solenoid to the intercooler piping is still there.. anyone know what this achieves?

ive noticed with the solenoid running off the ecu, running off a perm. ground, or not being grounded at all, all gives the same boost (runs about 50kpa/7psi all the time)

[smok74]

With over 15 years experience in electronics, I have never heard of a Ground/Earth wire in any type of circuit being white ?! ALL earth wires/leads are BLACK..... where's the common sense ppls ??

[kjb_r33]

With over 15 years experience in electronics, I have never heard of a Ground/Earth wire in any type of circuit being white ?! ALL earth wires/leads are BLACK..... where's the common sense ppls ??

ever seen the earth wire for the oxygen sensor on a EB to EF falcon.... WHITE.

Only mention this cause the same oxygen sensor fits the skylines.