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Hey guys. I've got a rough idle issue on my R34 GTT RB30/25DET Neo. I've worked on my RB for years and this is the first time where I don't have a fkin clue why it's happening, its baffiling me. Here's a video of it in action: Long story short: My daily R34 decided to randomly start doing this weird RPM idle fluctuation thing and it wants to die on me sometimes and I've got a higher than normal pressure in my fuel line before the fuel rail which I'm thinking can be contributing to this issue. The long story: This is my daily and the car has always performed really well for me up n till now. It was tuned on haltech platinum pro (running on board map sensor) 4 months ago and did 440hp (on 98ron) and has been driving really well, no issues what so ever. Then one day (about a month ago) I came home from work, fuelled up, popped into the shops and then came back, got in the car to head home, started it and it started idling really rough. Like, I would start it and then it would instantly die on me. So I had to rev it to keep the engine alive and I had to baby it home. And it would also do this weird RPM fluctuations where the rpm needle on the cluster goes up fast then down fast like its glitching weirdly (can see on the video). Note: nothing has been changed on the engine since the tune nor has the ecu been plugged into anything since the tune. So this problem has occurred randomly and is still the same today. Also to note: this happened when the car was at full operating temp (was probably a 30 degree day). And the same idle issue will happen on cold starts. I've attached my complete list of mods here. I haven't been driving the car since. So I've plugged the haltech ecu into my laptop to check for any error codes, nothing. I let the engine idle and I watched the sensors on the haltech ecu manager, nothing odd, and no errors. Temps all look good. TPS voltage is good. I've got the haltech hooked up to a wide-band O2 sensor (pro sport gauge kit) and the afr starts off rich on cold start then eventually it goes to 14.2 like normal, so afr seems fine and normal to me. Since I've changed the spark plugs, it now won't die instanly on me but it still idles weirdly. The weird thing is, the RPM on my cluster fluctuates up and down but the RPM on the haltech shows normal-ish (no fluctuations). Note: the video was taken after I have done all the checks below. So here's the list of things that I've checked off and done on my list to try and eliminate possible causes: • Compression test: perfectly fine like it was before the tune (phew!😅). • Changed spark plugs to new ones: this helped a bit with the rough idle, old plugs were all black (they were about 3000kms old). • Did the old quick coil plug test by un-pluging one by one while engine is idling to hear for changes in rpm: rpm/idle changed as they should on each one. • Changed fuel filter: still the same. • Checked TPS sensor on haltech and it reads correcly. 0.45v no throttle and 4v WOT. • Cleaned IACV with a new gasket: nothing changed. • Swapped the IACV with another known working one: nothing changed. • Swapped CAS to a known working one. Nothing changed. • Unplugged the water temp sensor: I know it’s not this because when I unplug it, it would show some weird temp on the haltech software and when i plug it in it shows normal. • I've tried attaching the R35 PRP coil plug harness's ground cable to somewhere els on the head: nothing changed • I've tried putting a jumper lead on the negative battery terminal and then attaching it to the head and block to see if its a grounding issue: nothing changed. • I've checked the timing marks on the cams and crank all line up. • Changed the fuel pump horn relay (constant 12v mod) to a new one: nothing changed. • I've taken my haltech ecu out and then tested it into my brother's r34 with his map to check if the ecu is still fine, and it is. Now here's where it gets a bit interesting (and let me know if it's irrelevant); I checked the fuel pressure for the first time ever by tee'ing in a pressure gauge between the fuel filter and damper that enters into the fuel rail (can see on the video). When I prime the fuel pump, it goes to 43ish psi, which it should be according to the R34 workshop manual. Then when I go to start and idle the engine, it stays on 50psi. The workshop manual says that it should be about 32psi. So I immediately thought its my fuel pressure regulator and I changed it to a known working one. And still... it's idling at 50psi fuel pressure. When I take off the vac line on the FPR, nothing really changes. So then I changed the fuel damper that sits on the fuel rail to a known working one: still the same 50psi. Then I hooked up a long hose onto the exit of the fuel rail straight to the fuel tank flap to see if there are any blockages: it dropped a little bit by 2psi... So no real restriction in the return line. So now Im wondering, if there might be a blockage in the fuel rail or my 640cc xspurt injectors are maybe blocked? 🤷‍♂️ The question I have is; is this fuel pressure on idle (50psi) normal for an RB that has a Walbro 225 fuel pump with the constant 12v mod, with upgraded injectors + standalone ecu on a stock fuel rail and stock fpr? And would this high pressure be my main culprit for my shithouse of an idle? The other interesting thing I found/tested, was; i swapped out the cluster to my old stock nissan one to see if the RPM fluctuation thing also appears on that one, and it did the same thing weird RPM fluctuation on my old nissan cluster. So something weird electrically is going on that is contributing to this idle issue (maybe?). The fuel pressure also doesn’t seem normal, so I wanted to check in with you guys before i go pulling the fuel rail off (which is such a bitch to do!). What do you guys think this might be? Can I test some other stuff? Does the haltech platinum pro ecu have a diagnosing feature of electrical components that I can try? It can't be the tune/map because it ran perfectly fine for 3 months after the tune and no one has touched the map since. The next thing I’m tempted to try is injector cleaner which I've never tried before. Can I pour it straight into the feeding fuel line instead of in the tank? Can injector cleaners damage stuff when not diluted in the tank? mod list.txt

Freshly rebuilt RB25DET Neo, all done by the one shop except for the machining, so the reassembly/rebuild, bed in on the dyno, and final tune. So far have done just under 1000kms since getting it back, and then this tick started happening. Was a bit quieter the other day when it started, took it to the shop to have a look, was told it was likely the VCT gear had shit itself because of where the tick was situated, and to take it home, i drove home cautiously and havent driven it since, but started it up today and it was suddenly louder and more rattly. The shop is taking it back later this week to see what the go is, has anyone else had a ticking like this? Sounds like its in the head, the spun bearing it had before getting rebuilt was a deeper knock and definitely down in the bottom if the engine, different to this, its alot higher pitched Thanks in advance people! IMG_0302.mov

Im in the process of swapping out turbos for a Hypergear ATR43SS-2. I bought a water/oil line kit from Mamba, for Garret GT30, according to Tao. All fittings fit properly, except for the water return line. It has a -AN fitting to hose barb. From what I see, I need to remove hardline and install hose barb fitting to rubber line behind the head. I located the rubber line but is there an easier way to gain access without taking valve cover or intake manifold off?

Hey guys looking for abit of guidance, I have put a 25det into my r31 and am having trouble getting it to idle it will rev fine and not miss but on idle it runs like abit of a dog and stalls, I checked the tps voltage and it was 5.10 with car switched off I’m unsure if that is in the perimeters? other then tps could the iacv be the cause or potentially vvt ? I realise it could be a range of things but have to start somewhere, cheers

Hey guys I have a r31 that I’m converting to a rb25 I have put a ffp on and the cable I got with the motor is miles to long, just wondering if there is a shorter cable out there I can buy, cheers 🙂

Hi people I’ve got an rb25det neo. Oil pump has been reconditioned. I’m getting consistent oil pressure, however, it’s quite low. At 80•c at idle it’s about 0.8bar and highest it ever gets at 7k rpm is at 3.2bar. 15w50 fully synthetic. I have an aftermarket sensor that is running to the maxxecu. My question is, is my sensor in the correct place? It doubles up at a temp sensor. If I wanted to check it with a mechanical guage, where would I plug it in?

Hey guys new here but at my witts end with my car and really looking for some help. Time for a long story. Owned my r34 NA Auto for about 9 years now. Car was running well until about 4 years ago when I started to get the A/T limp mode whenever the car went to shift into 3rd gear. Wasn't to fussed at the time as the car was about to go into the shop for a full motor and gearbox build. Car ended up with a full forged motor with turbo and all the bells and whistles which I haven't had a problem with. Gearbox was also completely rebuilt from front to back and absolutely everything is brand new. Car is running a haltech 2500 elite if that helps. Now to the pain. After all the money and things replaced it still has the same AT problem when it tries to shift to 3rd and it just sticks on 3rd gear limp mode from there on out. Car has always been and is still auto. It has the original box and motor in the car and me and my mechanic can not figure out why the hell it keeps happening. My next move is replacing the TCU module as it's separate in the GT model but other than that I'm lost Any ideas or help would be much appreciated Picture just coz I like to show it off. Thank you guys

Before you say this has been covered, I have exhausted over an hour today trying to navigate this site and going through greddy install diy posts. I don't need help on the full install I am fine with that I am confused on one aspect. Every greddy plenum I see installed in photos online do not show the aac valve connected to the pipe preceding the throttle body. When I look at the diy or other forum topics none of the images load, whether that's because the post is from over 10 years ago I'm not sure. If anyone can confirm what they did with their aac valve when installing a greddy plenum I'd greatly appreciate it. My tuner has heavily recommended I keep this for a number of reasons, suffice to say he is one of the best in qld. Car details - Rb25det - linkg4x - greddy plenum - high mount turbo gt35 - 1000cc injectors - forged pistons rods etc Situation - Street use and drift car at the track, not a daily car but would prefer to keep a/c and cold start. If anyone has any reccomendations, id appreciate it as i said. It doesnt make sense to me putting this into the pipe preceding the throttle body on top as its ugly and i csnt see that on any other setup, unless everyone runs it underneath or not at all im very confused... 😁

hi there i got a HR34 and it stop start i dont know why when i try to start the car it crunk but did not start and when i stop crucking it i get a sound from the trriger ( 3 or 4 tiking sound ) with a engine flashing i change everything and look at the timming for the engine every thing ok i got a haltech plug in ecu this a video for what happening

Hey everyone, been having a bit of a boost drop on the C34, it was getting its caster rods done the other day and i asked the guy who was doing it and he said the wastegate had a lot of play in it? do i know what that means... not really. but i was wondering what wastegates people here run? stock? aftermarket? just kind of want to see my options. to answer some questions which may be asked its a non neo motor currently does have a stock wastegate i do want to go for more power in the future thanks in advance who replies and tries to help out

Hi everyone, I'm currently in the process of building my RB25 Neo. I've read the entire oil control thread and have been implementing all the recommendations. I'm wanting to enlarge the 5 oil return holes in the head and block from 8 mm to ~9-10 mm. I found when aligning the headgasket using the dowels to the underside of the head, that the 5 oil return holes line up perfectly. It's just a matter of opening up the existing holes. Not too difficult. However, when sitting the headgasket (again aligned with the dowels) on to the block the 5 oil returns are all completely off centre (see picture below). If I were to enlarge the exisiting holes much more, they would protrude under the gasket. I have a spare R33 RB25 block, and it's the same thing. I also check using the original headgasket and it's the same. I thought the idea was to align the drill with the existing hole (on a mill or I've even read people doing it by hand) and enlarge it to 10mm to match the headgasket. Am I missing something? Any help or info would be super appreciated! 🙂

So I'm in process of building my 34gtt Will be aiming for about 500kw atw Have not spared a dollar on set up going full nitto forged bottom, g30-900, plazmaman manifold fmic, 1650cc Bosch (a lot more but you get the idea with my list) At what stage do you get an oil cooler and is it necessary or a wank factor? Car will be mainly street, occasional roll race and very occasional circuit Do they really make a difference? I will be sporting restrictors, head drain, nitto pump, baffled extended sump with high flow pick up and baffled cam covers TIA

Hey guys. So my bottom end has a potential issue, engine comes out to drop the sump later this week to see exactly what, has a bit of a knock on cold start up that goes away. My heads were recently done due to a found exhaust valve leak, so upgraded springs and retainers, and upgraded drop in cams while it was out. Heads went back on and we found the bottom end was knocking at high RPM (not very loud as was heard through the knock box and ear muffs) when they were doing a dyno run with the new head on. Car hasnt been started up again since I have the option to purchase a freshly machined and honed RB25DET block, with a R34 GTR RB26 Crank, Nitto rods, nitto oil pump, new head studs, main studs, new main bearings for $3500, will need to get my own pistons though as he used the pistons for his RB25/30 build he ended up doing instead, and has had the built block sitting for a while and wants to clear it out. Block had only been assembled for test fitment of everything, then pulled apart so he could use the Nitto Pistons he had in his RB30 build OR Get my current RB25DET Neo bottom end fixed up, possible machining, new bearings, new rings, etc etc. Wasnt looking to do forged internals but could go down that track Was looking to make 300-350 rwkw for now, maybe 400rwkw, as I do have all supporting mods already outside the engine to go to that power (besides the turbo but will upgrade that while im at it) Will i see much of a difference using the RB26 internals? I know the crank has a longer stroke, what advantages will I see and is it worth just getting the almost-ready-to-drop-in bottom end and going with that, or freshening up my stock Neo bottom end? thanks in advance

Hey all. I know there is a plethora of information about Hypergear turbos on these threads, with Tao providing a heap of Dyno results. I was looking at Hypergear's ATR45-SAT (Special application turbocharger) as it will directly bolt on to my existing setup, with some basic fabrication/relocation of some intake piping, and will suffice for my 300-350rwkw power figure I am after with my current setup for street use. Only thing is he doesnt provide any specs from what I can see on the size of the housings, or any sizings of inlets/outlets, which I thought would be basic information you would provide there for your customers to see when deciding to choose your product, like other turbo sellers do. Has anyone got some of their own feedback and dyno results on that specific turbo? Was also looking at Kinugawa turbos that were a direct bolt on, and had heard good things about them, I dont think theyre as popular as they used to be, but has anyone had one recently theyve purchased and used? Any other recommendations with reasoning as to why they went with it?

Hello wondering if someone could tell me if a 38mm external wastegate would be adequate for a 25det running a psr 3076 .82 only looking for around the 300kw mark (or there abouts). My top mount has a 2bolt flange for the wastegate and as far as I can see anything over 38mm is v-band, if possible I’d like to not have to modify the manifold, thanks in advance sorry if this has been asked but I could not find any threads about it.

Hey guys just wired in a 25 into my r31 the car runs and starts fine but am having trouble understanding how to wire up the vct/o2 my understanding is they are powered off the same wire, I’ve read elsewhere that one wire for the vct goes to ign 12v and the other to ecu pin113, hoping some can shed some light for me as there are only 2 conversion guides I can find but one is just a alteration of the other and isn’t any clearer to me, cheers

I am about to install a Rb25 turbo on my Gtst rb20...but the turbo didn't come with an inlet elbow and I know the rb20 one won't fit. Does anyone have an extra one they could part with? If so please reply with asking price.

Who has used one? Has anyone cracked a block since fitting one? Discuss.

Hey guys so after a comp test my engine has busted rings leading to 40psi. So I’ve taken them all apart. I’m the first owner in aus from Japan. My rods don’t all line up properly in numerical order. Also my piston caps have been stamped. Does this mean this engine was rebuilt with stock parts at some point ?

Ok here’s a list of exactly what I’ve done for my r33 neo. This is whilst retaining all r33 bolt ons, plenum, oem coilpacks with the loom, injectors & rail with the loom using a s2 R33 rb25 engine loom and starter motor loom. comtinues to turn really strong, but no firing up. Fuel pump works fine -changed plug for o2 sensor to suit neo -changed vct solenoid plug to suit neo -extended the TPS plugs to reach neo throttle body -reversed cas -variable air control intake solenoid valve plug changed to suit neo & canister purge control valve plug to suit neo That’s about it. IGN relay is there, ecu is in, white thing is plugged in I’m pretty sure it’s in properly.

Up for sale is my supertech solid converted RB25 head, Genuine GReddy Intake Manifold with Plazmaman Rail and 1650cc Bosch Motorsport E85 Injectors. RB25 Supertech head - 1mm valves, solid lifters, big port job, runs RB26 cams clearanced for 10.25mm lift. Just had freshen up, new valve seats cut and face skimmed. $2000 DOES NOT COME WITH CAMS. GReddy with 82mm TB, Rail and Injectors $1600 Also have 3/8 L19 Rod bolts. Came out of my spool rods. $200