Jump to content
SAU Community

Rb25det Boost Tappering Off.

RicsR33

By RicsR33,
in Engines & Forced Induction

 Share

Recommended Posts

RicsR33 Enthusiast

RicsR33

Posted
Posted

Hi Guys/Gals

Ok so ill start from the start.

Took my car in to get the following mods tuned.

t04e - plain bush bearing (I KNOW) (wastegate port has be honned out)

Aftermarket low mount manifold

Bosch 040

SAFC

blocked bov (yes stalls sometimes- so there was no fabrication to the intake pipe)

3inch intake pipe

catch can (yes hooked up correctly - so there was no fabrication to the intake pipe)

3 1/2 inch exhaust

Apexi Pod

$22 ebay boost controller

Was hoping to see around 200-220 kw atw (with my stock ecu and average turbo)

When my tuner did a few base runs, we saw the boost spike to 14psi and the ecu chucking a mental, even losing a 100 hp through the midrange the car still made a top of 269hp atw running rich.. As we were searching for the problem for the spike saw and felt the actuator rod not opening the wastegate fully, once i adjusted the tension on the actuator rod the car was no longer spiking but would hit 11 psi and fall off to around 6psi by redline which was only making around 230hp. we came to the conclusion that it was the crappy dual port 4 psi actuator. so he tuned the car quickly with what we had to work with, took some fuel out since it was still running mega rich.

next week i shot down to MTQ and bought a garret 8psi actuator, put it on and went for a quick run around the block before the tune, from what i saw on the boost gauge it seemed to be holding .6 bar fine. we put it on the rollers and did a base run, boost was around 10-11 psi but tapered off to 7 psi, checked the tension on the rod and there was enough spring tension to hold the wastegate shut also the car was down 10kw from what it was a week ago. and lost quite abit of power in the mid range also was running a little leaner then a week ago, we tried winding the boost controller right up, it only added 1 psi and still lost boost to 7. We the turned the boost controller completely opposite way it made a constant 4psi right across the rev range?? souldnt it be 8psi since thats what the actuator is? we also tried a GFB controller on it as well with same results. We then checked the part number stamped on the actuator and it is indeed a 8psi. No matter what we tried the boost was leaking off..

Now could this be a restriction in the exhaust? (was thinking of droping the exhaust from dump and see how it runs, then maybe from exhaust housing if it made no difference from there) its a JJR Turbo back exhaust with a split down pipe and "high flow cat"(not actually to sure how high flow lol)

What are some of your idea's? bellmouth? i cant see why it could spike and build to 14psi but now it cant even hold 11psi?

sorry for my life story just wanted to try and explain fully to you guys.

Thanks Richard

Link to comment
https://www.sau.com.au/forums/topic/305486-rb25det-boost-tappering-off/
Share on other sites
mosquitocoils Veteran

mosquitocoils

Posted
Posted

It could simply be the manual boost controller... I think they don't hold boost well in the upper rev range. Have a search here on SAU, it's well documented.

You kind of have to weigh up the pros and cons - $30 for a controller that holds pretty well, or $500 for an EBC.

I'm happy with the turbotech manual controller hahaha.

And if I didn't understand the problem properly, I apologise

R31Nismoid Grand Master

R31Nismoid

Posted
Posted
It could simply be the manual boost controller... I think they don't hold boost well in the upper rev range. Have a search here on SAU, it's well documented.

Say what? Any links to where such a statement is well documented?

I've never read such posts...

Properly setup, boost control, will work fine regardless of if it has flashy lights and buttons or a screw top.

I've never used anything other than a bleed valve. Made over 370rwkw, 24psi @ 8000rpm.

So it comes down to installation 9 times outta 10.

RicsR33 Enthusiast

RicsR33

Posted
  • Author
Posted

nismoid i know you know quite abit what are your idea's or solution? ive checked the vac lines, my controller comes off the cooler pipe to the boost controller then to the actuator. the vac's are brand new and the actuator is brand new, tension seems correct. I did also mention we tried a gfb controller on it as well with the exact same result. hmm

R31Nismoid Grand Master

R31Nismoid

Posted
Posted

drop the exhaust first, see what happens.

also when the internal gate was ported, was a new end cap used, larger one so that air does not go past?

Why was the rear ported anyway? They flow enough for the turbo they are.

RicsR33 Enthusiast

RicsR33

Posted
  • Author
Posted

yer when i got the turbo the port was only at 20mm, i was told this causes spiking on alot of these shit turbos so i got my fitter and turner at work to port it out to around 29mm, hyper-gear then built me a rear flange with a 33-34mm wastegate flap, im almost 100% sure that it overlaps the port by atleast 1mm all round, yea the exhaust will be the first thing to drop tommorow when im back at work with access to a hoist.

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
 Share
Go to topic listing


  • Similar Content

  • Latest Posts

    • Duncan
      7 Speed Auto transmission fluid change (Skyline, Q50, Q60, Fuga, Q70, A62 Titan and probably heaps of others including Navara...)

      By Duncan · Posted

      I thought I'd do a write up on an auto transmission fluid change for a the nissan 7 speed Automatic. At some stage the genius engineers decided that the fluid in the trans was "for the life of the transmission", (which seems kind of self supporting to me) and removed the dip stick and fill tube (funnily enough there is still a casting for it). Anyway, for this job you do need 2 specialist tools in addition to regular hand tools, jack and good chassis stands. You need a way to pump fluid up to the transmission; I got one of these but there are plenty of other options: https://www.ebay.com.au/itm/364584087070 Don't trust the generic listing though, it does not come with the required adapter for the Nissan 7 Speed. You need one of these, can't do the job without it: https://navarapart.com.au/product/genuine-nissan-patrol-y62-d23-np300-navara-re7-dipstick-fill-connector1 You need a heap of compatible transmission oil. Could be Nissan, could be anything else rated for Nissan Matic S. You need at least 10 litres, I had 15 to give it a better flush... Also, you need some biiig oil catch trays, at least one of these, or bigger if possible (volume was fine, size was very marginal): https://autobarn.com.au/ab/Autobarn-Category/Tools-%26-Garage/Specialty-Tools/Oil-Service/Garage-Tough-Oil-Drain-Pan-Black-16L---GT1068/p/TO03191 Finally, a measuring jug is very useful if your pump does not have volumes marked on it, I got a 6l one: https://www.repco.com.au/oils-fluids/fluid-accessories/measuring-jugs/penrite-measuring-jug-6l-pmj006/p/A5322648 Oh, and gloves.....this stuff is horrible (not as bad as diff oil, but getting there) ....First, jack up your car.....
    • Duncan
      Duncan's V37.......race car?

      By Duncan · Posted

      So I mentioned the apprentice, @LachyK helped take the bonnet off. We just undid the nuts on the hinges and unclipped the gas struts, then pulled the bonnet back a little as the front was catching on the front bar.  I had a good look at everything today and have removed the rams, repaired/reset the hinges and bolted it back together like it never happened. I'll do a separate write up on the repair, and I also removed the poppers from the Fuga today too to save grief down the road.....as said above it is at least $5k to repair retail. I'm also happier about my ability to prepare a race car, and less happy about Nis-nault's engineering (I can hear @GTSBoy sAfrican Americaning) because the top hose of the radiator didn't slip off.......it snapped clean off. By practice I put the hose clamp hard up against the flare on a neck to make it least likely to ever move (thanks @Neil!). I guess that puts a little more pressure on the end of the pipe as it is further away from the rad, but still, that is pretty shit. I've put it back on for now as there was a fair bit of neck still there, but obviously there is no lip on the neck any more so I don't think I'll track it again until I have a new rad. Speaking of which....more research required. It looks like Koyo makes a standard size radiator in ally which I'll grab in the meantime, but I really want something thicker so might have to go custom in the medium term (ouch) Coolant still needs a refill and I have the pressure tester on it over night, but other than a wash down of the engine bay it seems alright. And @MBS206 noted something noisy on the front of the engine and I think I agree....time for a new accessory belt and tensioners I think.
    • Duncan
      Duncan's V37.......race car?

      By Duncan · Posted

      our good friends at nismo make a diff for it, I have one (and a spare housing to put the centre in) on the way. https://www.nismo.co.jp/products/web_catalogue/lsd/mechanical_lsd_v37.html AMS also make a helical one, but I prefer mechanical for track use in 2wd (I do run a quaife in the front, but not rear of the R32)
    • GTSBoy
      R33 persistent issues. P/steering and lag/misfire

      By GTSBoy · Posted

      What are we supposed to be seeing in the photo of the steering angle sensor? The outer housing doesn't turn, right? All the action is on the inside. The real test here is whether or not your car has had the steering put back together by a butcher. When the steering is centred (and we're not caring about the wheel too much here, we're talking about the front wheels, parallel, facing front) then you should have an absolutely even number of turns from centre to left lock and centre to right lock. If there is any difference at all then perhaps the thing has been put back together wrongly, either the steering wheel put on one spline (or more!) off, and the alignment bodged to straighteb the wheel, or the opposite where something silly was done underneath and the wheel put back on crooked to compensate. Nut there isn't actually much evidence that you have such a problem anyway. It is something you can easily measure and test for to find out though. My money is still on the HICAS CU not driving the PS solenoid with the proper PWM signal required to lighten the load at lower speed. If it were me, I would be putting either a multimeter or oscilloscope onto the solenoid terminals and taking it for a drive, looking for the voltage to change. The PWM signal is 0v, 12V, 0V, 12v with ...obviously...modulated pulse width. You should see that as an average voltage somewhere between 0V and 12V, and it should vary with speed. An handheld oscilloscope would be the better tool for this, because they are definitely good enough but there's no telling if any cheap shit multimeter that people have lying around are good enough. You can also directly interfere with the solenoid. If you wire up a little voltage divider with variable resistor on it, and hook the PS solenoid direct to 12V through that, you can manually adjust the voltage to the solenoid and you should be able to make it go ligheter and heavier. If you cannot, then the problem is either the solenoid itself dead, or your description of the steering being "tight" (which I have just been assuming you mean "heavy") could be that you have a mechanical problem in the steering and there is heaps of resistance to movement.
    • MissMintyR33
      R33 persistent issues. P/steering and lag/misfire

      By MissMintyR33 · Posted

      Little update  I have shimmed the solenoid on the rack today following Keep it Reets video on YouTube. However my steering is still tight. I have this showing on Nisscan, my steering angle sensor was the closest to 0 degrees (I could get it to 0 degrees by small little tweaks, but the angle was way off centre? I can't figure this out for the life of me. I get no faults through Nisscan. 
×
×
  • Create New...