Jump to content
SAU Community

Recommended Posts

Hi guys,

As gay as it sounds, I need to turn the boost down on my R33 GTR. Its my first GTR and im still getting to know all the biz about them. It's hitting 17psi and running the standard turbos. Surely this can't be good! Basic run down of mods are power fc, air filters, full exhaust (standard dump pipes) and from what I believe, the 'free boost upgrade'. I had a look on the boost solenoid and the is no yellow line on the black hose which leads me to believe the hose has been changed? What would be the easiest way to bring the boost down? I was thinking of putting in a bleed valve to get me by or even put in a ebc (which i prefer). I plan on changing the turbos down the track but have other priorities right now and will have to wait a bit hence why I want it to last a bit.

Your help is greatly appreciated.

Thanks,

George

Link to comment
https://www.sau.com.au/forums/topic/424751-help-me-bring-my-boost-down/
Share on other sites

clearly there is already a bleed valve or ebc to get it to 17psi and tune to suit. im guessing you have just bought a car without knowing what aftermarket parts controls its boost??? maybe the power fc ebc kit. remove the vac line from the controller and plumb them straight to the wastegate, if you lower your boost a lot you will run quite rich when the tune expects 17psi and gets 10psi

Edited by Jayden.K

Thanks for the info. Yes, i have just bought the car a few weeks ago. It definitely looks as if there is no boost controller of any kind. Still retains all the factory lines from the actuators etc to the factory boost solenoid. When you say remove the line from the controller and plumb it to the actuators, are you referring to the 2 boost solenoid hoses? ie. join them together?

Thanks

George

ok. decided to go out in this cold melbourne weather and have a look around. there is no aftermarket boost control kit or pfc ebc kit. what i did find was interesting though. i pulled off one of the lines found a bolt in one and thought...oh no...and on closer inspection, there was some holes in the actuator line. i pulled the other one off aswell and that was blocked off too. i pulled the bolts out and have connected them to the solenoid so it works as it should. It now runs 12psi @ WOT which im much happier with. it boosts much better, comes on boost quicker and drives better. its a tad slower as the boost has dropped, but i think this is better. attached are some pics. if you have any other ideas on what i could do, please tell me! haha.

IMG_0212_zps7a173456.jpg

IMG_0214_zps02d95e6a.jpg

IMG_0215_zps810a9557.jpg

that is some crazy dodgy work lol. now that the boost is lower it wont feel very quick puling from 5 to 8 grand. plus it maybe running rich now which will bog it down, so when it use to see over 12psi it will add fuel to compensate (aka thats it tuned) now the airflow isnt there, its just waking fuel in for 17psi of boost when there is only 12. fact is if you have a pfc, you must get it tuned when you change things like this

Edited by Jayden.K

also sense you have a hole in your vac line. it will pay to get your boost leaks check. it will run so much better if you fix any. do this before you tune again. otherwise it will run lean if tuned with leaks, then you decide to fix them

Jayden.K - Thanks heaps for your input. I wasn't too sure if the air/maps are locked in the PFC which sounds like it is. I've just been cruising it and not taking it past 5k as it doesn't really have much pull from there onwards. It sort of flat spots. It definitely runs better they way it is set up now and i have replaced that hose with the holes in it and have gone over the vac lines and have not found any vacuum leaks. Looks like im going to book it in for a tune really soon then :)

to easy mate, btw vac leaks and boost leaks are 2 different things but if you have a leak at vac you will with pressure. you will need a pressure tester to put into your intake, force air in and when you close the valve you will hear air coming out in all sorts of places, i had no leaks at 5 psi but then leaks at 20psi. things like hose clamps/ split hoses, gaskets etc. then after there fix, it will pay to check it every 6 months or whatever. ask your tuner if they can perform this, if they dont no what your on about get another tuner.

maps are locked, unless at hot idle or cruising then it switches to closed loop and reads the o2 to calculate a/f ratio.

its really shit because if the car knocks, it doesn't retard timing. it just follows the map!!! something that comes in handy on steep inclines, burnouts and hot days which shoot knock readings up from engine load. not sure if other ecus do it like vipec/haltec, motec, wolf v2, nistune piggy back blah blah

Edited by Jayden.K
  • Like 1

that is some crazy dodgy work lol. now that the boost is lower it wont feel very quick puling from 5 to 8 grand. plus it maybe running rich now which will bog it down, so when it use to see over 12psi it will add fuel to compensate (aka thats it tuned) now the airflow isnt there, its just waking fuel in for 17psi of boost when there is only 12. fact is if you have a pfc, you must get it tuned when you change things like this

What?

Dropping the boost won't make it run rich. if it is tuned for 17, it can obviously run 12, because it would have been with part throttle. The afm will read the airflow and add the correct amount of fuel, less boost, less afm voltage, less fuel.

What?

Dropping the boost won't make it run rich. if it is tuned for 17, it can obviously run 12, because it would have been with part throttle. The afm will read the airflow and add the correct amount of fuel, less boost, less afm voltage, less fuel.

I agree, ECU will adjust fuel depending on load (AFM voltage) Regardless of PSI. Would be different had the boost been raised above 17..

Wow. More info. I knew with the standard ECU they self-adjusted, just wasn't too sure with a Power FC (never owned a car with aftermarket computer before so its all new to me!)

From what i have read, running the way i have it now, a lot of people get 1bar (14psi) boost. Why would i only be getting 12psi? It also doesn't feel like it pulls from 5k-8k the way it use to. Can anyone shed some light on this? Should i disconnect the battery to reset the computer?

Thanks,

George

What?

Dropping the boost won't make it run rich. if it is tuned for 17, it can obviously run 12, because it would have been with part throttle. The afm will read the airflow and add the correct amount of fuel, less boost, less afm voltage, less fuel.

I agree, ECU will adjust fuel depending on load (AFM voltage) Regardless of PSI. Would be different had the boost been raised above 17..

I concur with the concurring. Jayden no correct.

sorry, i thought that was how it worked with power fc.

Edited by Jayden.K

Yuh, PowerFC same as Nissan ECU. Measures load with AFM, so it's not tuned "for a boost level" so much as it is tuned quite naturally according to the amount of air going in. Less boost = less air = just running from a lower load part of the fuel and timing maps, exactly as if you were using part throttle.

When I say "not tuned for a boost level".....that's not entirely true, but it's close enough. Obviously if you have more boost you end up needing maybe richer mixtures and more conservative timing. But it's not really possible to separate these effects for a given turbo+ECU+AFM+engine combination....so the tune is effectively not dependent on boost as much as it is on raw measured airflow. For that given combo, less air must mean less boost, whether that airflow/boost is turned down by throttle or by boost controller doesn't make much difference.

If you increase boost above what it was tuned at, you will go off the end of the old tune and out into unexplored territory and you might blow it up (lean mixtures or too much timing the main thing here).

Yuh, PowerFC same as Nissan ECU. Measures load with AFM, so it's not tuned "for a boost level" so much as it is tuned quite naturally according to the amount of air going in. Less boost = less air = just running from a lower load part of the fuel and timing maps, exactly as if you were using part throttle.

When I say "not tuned for a boost level".....that's not entirely true, but it's close enough. Obviously if you have more boost you end up needing maybe richer mixtures and more conservative timing. But it's not really possible to separate these effects for a given turbo+ECU+AFM+engine combination....so the tune is effectively not dependent on boost as much as it is on raw measured airflow. For that given combo, less air must mean less boost, whether that airflow/boost is turned down by throttle or by boost controller doesn't make much difference.

If you increase boost above what it was tuned at, you will go off the end of the old tune and out into unexplored territory and you might blow it up (lean mixtures or too much timing the main thing here).

yep cool, i just thought powerfc were really basic computers and once it set thats it, guess i learn to never assume anything. sorry about the incorrect information

you've all been very helpful with the problems i've experienced.

But can any one shed some light on what i posted earlier?

see below.

thanks

From what i have read, running the way i have it now, a lot of people get 1bar (14psi) boost. Why would i only be getting 12psi? It also doesn't feel like it pulls from 5k-8k the way it use to. Can anyone shed some light on this? Should i disconnect the battery to reset the computer?

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now


  • Similar Content

  • Latest Posts

    • My experience with Rising Sun Exports Before agreeing to the sale I tried to do as much research as I could (obviously), his Facebook reviews are 98% and he goes Live at least once or twice a week. I contacted 2 people in the UK who had used him for their imports, both had positive feedback. His explanation and talk through of the import process was thorough, answering any query no matter how stupid it was. It felt as soon as the money was sent, communication dropped off. I asked for shipping updates every 2 weeks or so, not wanting to pester him, he never had any updates. I wasn't informed the car had been dropped off at the port, I only found out by his Facebook story. I asked for the photos taken at the port, knowing he would need some for insurance purposes. I received a few 5 second clips and that's it. When asked again, he said his staff had them. Weeks later I asked again, he tells me he doesn't have any, but does have 50 photos from the original advert. I never received them. I eventually got the documents sent via WhatsApp after I mentioned the port was requesting them. I purchased a CarVX report, to find out the vehicle is a Grade R with recorded accident damage, first recorded in 2017 when it was first auctioned. He never told me the grade, then again I didn't ask. His response was "Grade R means nothing, it wasn't chassis damage". Still, I would have liked to have been informed about it. Jon prides himself on being open and honest when it comes to inspecting cars, it's his main job doing so at the auctions for customers. When the vehicle arrived in the UK I noticed a few little cosmetic issues. It's a 21 year old car so it wasn't going to be mint condition. The side skirts are cracked on each corner and the sealant is failing. The front grill on the bonnet/hood isn't secured very well, mounting studs are missing. Both minor things, but again, it would have been nice to be told. During a Facebook Live walk around video of the vehicle, he mentioned it has a front Whiteline anti roll bar/sway bar. While on the inspection ramp, I noticed the stock item has been installed. When first questioned, his response was "the ARB? Switched? Since when, it never had them". Since sending video and photo evidence I've not received a response. I'm probably being over critical of the overall condition of an old car, but all I wanted was honesty (which he claims to have). I'm aware I wasn't his only customer, he's busy doing XYZ but other reviews praise him for great communication with regular updates and photos, I felt I didn't receive the same treatment. 
    • I was able to get some underside photos while the car was on the ramp The suspension is all Altezza/IS200/IS300 so getting part's will hopefully be less of a headache
    • Welcome to my 2004 Toyota Mark ii IR-V Fortuna (series 2) With a 1JZ-GTE powerplant under the bonnet (hood) it'll give me plenty of scope for power upgrades. For those who aren't familiar with imports, the 1JZ-GTE is a 2.5L 6 cylinder VVTi engine with a single turbocharger. This has the factory R154 5 speed gearbox, along with a aftermarket 2 way LSD differential (brand unknown). Under the arches are a set of CST Zero 1 alloys, 18x9 +30 225/40 up front and 18x9.5 +15 265/35 on the rear. The car was quite low in Japan and there's evidence of the wheels catching the rolled arches/fenders. The tyre's aren't great so I'm in two minds whether to replace both or just the tyres and put up with the wider wheels on the rear. The car still uses stock brakes with the addition of some braided hoses. The exterior is stock with the exception of a BN Sports front bumper and a replacement Fortuna grill  Moving to the interior, the steering wheel has been replaced with a dished MOMO steering wheel (which will get swapped for my Momo Tuner for the time being) Defi Link Gauges are mounted above the climate controls and on the A pillar, the Oil Temp,Oil Pressure,Water Temp and Boost gauges should help with spirited and track driving  The stock seats have been replaced with some retrimmed Recaro bucket seats. Being a larger build these are a little snug, unfortunately the orange isn't for me so I'll look into replacing these down the line. Other modifications include a twin plate clutch, Blitz intercooler, Evolve alloy radiator, a stainless exhaust with decat, HKS EVC-S boost controller and coil overs
    • Apologies for the long read My R34 GTT was up for sale at the beginning of spring due to a few repairs creeping up. The strut tops needed replacing, roof and bonnet (hood) painting (yay for 3 stage pearl) and the underside stripped and treated. I sold the car which allowed me to be in a much better place financially. Leading up to the sale I was already thinking about the replacement. In an ideal world it needed to be a good all-rounder. Something I can mess around with, modify, do track days, do the school run, go on long drives etc.  Options included but not limited to... Laurel C35, Evo 8/9, Civic FD2, Impreza Hawkeye, Aristo and even an Audi S4 Avant (I've already got the Mazda 6 wagon). But there was always one car at the top of the list The Toyota Mark ii JZX110 I found an advert on a Facebook group for an example in Japan, from a seller called Jon at Rising Sun Exports. A few messages back and forth and Jon calls me from Yokohama one morning (or afternoon in his case). He briefly explained the import process, the costs involved and a repeat of the advert. After much deliberation, the price was agreed and the sale was locked in. I've never imported a vehicle so I jumped into the unknown head first. The money transfer was completed through wise.com (fees apply), very easy to use and the money was with him within a day or two.  The car suspension was raised for the vessel and the car dropped off at the port. It was 7 weeks later when the bill of lading was received and the freight invoice sent to me, followed by the export certificate a couple of days after (both digital copies) In the mean time the port had been in contact. I needed an agent to deal with the NOVA (notification of vehicle arrival) along with the tax/duty invoice, this was £75.00. The port also had a fee of £100, I'm guessing to cover the cost of the 10 day 'free storage' and for moving the car off the boat etc. They need a copy of the vehicle invoice, freight invoice and export certificate to allow the vehicle to pass through customs. The vessel arrived on Tuesday 5th August, the tax/duty invoice was generated and sent over. This is generally tax 20% and duty 10% of the vehicle value. Although the invoice came in at a higher amount than I had calculated. Once HMRC had received the payment the vehicle could be released from customs. I thought once the tax/duty was paid you could collect at any point, that's not the case. Your agent will need to book a collection slot, I requested Thursday 7th which was accepted, with a 9:00am slot allocated. It was a 5:00am start from Norfolk heading to Southampton. We eventually found the compound, upon presenting the bill of lading and some ID they released the car (they drove it out of the compound to the front ready for us to load up). The email from the port stated each slot had a 10 minute window, which seemed abit farfetched but the staff said it's not a strict rule. We were there for approx. 30-40 mins in total. A week prior to collecting I contacted my garage and explained the situation, I was able to get an inspection slot that afternoon. For the registration, DVLA require the car to be insured, for this I used a company called Adrian Flux who can insure the vehicle using the VIN number. 
    • Hey guys, looking for these side skirts if anyone can help me out. 
×
×
  • Create New...