Trying To Work Out Why My Car Is Boosting At 11.5psi

[Galois]

thought (ie: question lol)

ok, there seems to be some sort of stock boost pressure controller, im guessing this is the thing that allows the change from 5-7 psi. its the thing that both the actuator and intake pressure piping lead to and has an electrical input as well.

can the ecu change this setting? what is the electrical wire there for?

cheers,

ben

[RANDY]

thought (ie: question lol)

ok, there seems to be some sort of stock boost pressure controller, im guessing this is the thing that allows the change from 5-7 psi. its the thing that both the actuator and intake pressure piping lead to and has an electrical input as well.

can the ecu change this setting? what is the electrical wire there for?

cheers,

ben

Yer, the ECU will control the solanoid so that it allows the wastegate to open at 5psi up to 4500rpm, and then 7psi over that.

The grounding mod mentioned way earlier basically tricks the solanoid into bleeding more air off all the time, so 7psi can be achieved <4500rpm

[Galois]

can that solenoid be changed to the boost pressure is higher than 7psi

Edited July 4, 2010 by Galois

[maddowse]

can that solenoid be changed to the boost pressure is higher than 7psi

i think it would be very hard to do that .

have you felt the pipe between where the solinoids join and the actuator to see if theres a restricter in there ???

also no i havent gone for the power run yet !! once i found out about the actuator i relaxed a bit, but iv got one bloke who wants me to get one done because his coupe has been dynoed at 190kw but my car is a bit more wildly than his (earlyer boost and it hit a bit harder and looses traction alot ) lol im a bit of a led foot though but it would be interesting whats going on under the hood .

[maddowse]

can that solenoid be changed to the boost pressure is higher than 7psi

oh yeah and we did that high boost mod to my mates car and it runs 10psi when he puts the foot down !!!!

how is your exhaust ? because people say putting a front pipe / dump pipe will raise the boost so i was thinking what if you just have a very straight (loud) 3" cat back ? can that rais it

[Galois]

oh yeah and we did that high boost mod to my mates car and it runs 10psi when he puts the foot down !!!!

how is your exhaust ? because people say putting a front pipe / dump pipe will raise the boost so i was thinking what if you just have a very straight (loud) 3" cat back ? can that rais it

i think so. but it's boosting way up at 13psi so it's probably more than just the zorst, i have a 4.5" random cat back that came with the car, still have to check the boost gauge, which involves figuring out how to take it off lol, shouldn't be too bad

Edited July 5, 2010 by Galois

[Rolls]

I was running 12.5-13psi on my RB20DET with no boost controller. The reason is once you add a freeflowing exhaust it removes backpressure on the wastegate making it open easier. That coupled with intake, fmic, higher boost etc all make it creep up higher than stock.

It is completely normal and there is no way to make it lower apart from putting the car back stock. Personally I would just get a FMIC and get a nistune, should make 190kw at least and be very nice to drive.

[Galois]

isn't it risky running higher than 12psi though?

[Rolls]

isn't it risky running higher than 12psi though?

The turbo shit itself recently (I sold the car), but it ran for about 30,000kms at that boost without issue. Car had about 140,000kms on it at the time. Was the older redtop ECCS rb20det as well.

If you are running much higher eg 15+ then yes it is definitely risky. Any boost level about standard is going to reduce the life of the turbo, there are just so many factors when figuring out how long until it dies though.

Edited July 6, 2010 by Rolls

[Galois]

how different are rb20det turbo's to r34 gtt ones tho? sorry to ask, but the general consensus in this thread and many others is that above 12psi on an r34 is asking for trouble

[Rolls]

12psi on a 2.5L motor is pushing way more air than 12psi on a 2L motor, hence the 25 turbo is spinning far harder in that situation.

[Galois]

Wait!!!!

Hope you haven't already bought a new actuator mate, because I've made a discovery!

I had a mate of mine who is an absolute car nut have a look at it after 6 months of trying to find the cause of the increased boost. I explained to him there is an effective boost controller that came stock changing from 5-7psi at 4500rpm. He followed the piping for 2 minutes and said: "disconnect this pipe, block it off and see what happens" referring to the top pipe on the cylindrical boost controller solenoid me-gig.

And I did. And I had 7psi.

So, as I figure it, the solenoid has been tampered with to bleed off until 13-14psi. Or, it's bleeding off at a slow enough rate that the psi gets to 13-14 before the air flowrate overcomes the compression. But I doubt this because I don't think it's work, why could it bleed happily at 5 but then struggle at 14. Then again, maybe that's exactly how it works... I'm guessing it's possible to modify the ecu control of the boost controller...

Hope it helps mate, give it a try, I actually prefer mine with the lower boost. If feels happier, less insane, more speed limit friendly, and still leaves enough cars for dead. Will prob get a boost controller some time in the future and set it up with a nice safe 10psi mode for the fun times.

[paulr33]

hmm kinda all over the shop here...

the std solenoid cannot provide less boost than the actuator on the turbo

that is, if the car has a 7psi actuator spring, dual factory boost solenoid or not, the minimum boost you get is 7psi

so even if you bypass it, you get 7psi

you can only use solenoids or controllers to give you more boost, not less than the actuator spring

all the solenoid (or other controllers) do is mask the pressure signal or restrict it a bit so the actuator opens later

the ECR33 (manual) is a 7psi actuator and a dual stage boost solenoid factory that bleeds an extra 2psi past 4500rpm

so if you remove the solenoid or ditch it or cut it out, then you only get 7psi regardless

the only way you could make the factory solenoid give you more boost is if you physically modify it - ie narrow the diameter inside it, even then it probably wont work very well

[Galois]

Blocking off that pipe gave me 7psi rather than 13-14, so either the guy who did it was successful or it was stuffing up. I'm assuming the pressure gauge doesn't need a new calibration.

ps: I say 13-14 psi because it seems to change every now and then. But the understood maximum safe boost is supposedly 12psi for and r34 turbo...

Edited September 11, 2010 by Galois

[paulr33]

which pipe are you referring to?

if you block the actuator signal and give it no manifold pressure you run unlimited boost, that is, boost will continue to climb for ever and peak where the exhaust housing / compressor wheel are at the limits, this is usually well past 1 bar so dont try doing that. i see no way possible of getting 13/14psi with the factory solenoid and std actuator unless youve modified the std solenoid or using your own bleed valve etc or just leaving it on unlimited boost mode and hoping for the best

if you block the dual stage solenoid and run the vac signal straight to the actuator, you will get what the actuator spring is, so if its a 7psi spring in the ER34, then you get 7psi

if the dual solenoid is working and connected properly it might bleed another 2psi, giving you 9psi at a set RPM somewhere (ECR33 is 4500rpm) so ER34 might be similar.

[Galois]

which pipe are you referring to?

if you block the actuator signal and give it no manifold pressure you run unlimited boost, that is, boost will continue to climb for ever and peak where the exhaust housing / compressor wheel are at the limits, this is usually well past 1 bar so dont try doing that. i see no way possible of getting 13/14psi with the factory solenoid and std actuator unless youve modified the std solenoid or using your own bleed valve etc or just leaving it on unlimited boost mode and hoping for the best

if you block the dual stage solenoid and run the vac signal straight to the actuator, you will get what the actuator spring is, so if its a 7psi spring in the ER34, then you get 7psi

if the dual solenoid is working and connected properly it might bleed another 2psi, giving you 9psi at a set RPM somewhere (ECR33 is 4500rpm) so ER34 might be similar.

Ok, well i just realised that my piping setup may differ from other peoples, so here's what mine does:

Just after the compressor on the intake pipe heating to the intercooler a small hose goes to a t-piece. One hose goes from the t-piece to the top of the solenoid, the other goes to the actuator. Another hose goes from the bottom of the solenoid to the air feed line before the intercooler.

I hope that is right.

14.7psi ~ 1bar, I would think a turbocharger would run much higher than that with no actuator right?

Blocking off that pipe had the exact same effect as disconnecting the solenoid. I'm guessing the solenoid has been grounded, as when the solenoid is connected to the network it runs >7psi at 3000rpm, whereas when it's disconnected it runs 7 constantly. It is really interesting to drive the car like that: my faulty coilpacks and dying clutch love it haha. And full throttle in firse gear doesn't spin the rear tyres, much better for when other people drive it lol.

The only thing I can think of is a faulty/modified solenoid, is there any way of investigating this? I can only imagine it would take some effort and thinking to do. I guess if you're really keen to pass inspections it's easy free boost.

Has anyone ever modified in this way?

Thanks for the help

Maddowse mate, give it a go, see what happens...

[Galois]

I'm thinking of connecting the stock boost controller solenoid to a switch in the car, switch off gives 7psi, switch on gives >13psi. It might serve as a duel stage boost controller till install a real one.

Also, there is certainly less of a whooshing noise from the turbo/solenoid which may have been from the boost, or from the solenoid bleed. Just a thought.