Joni Boi

I know right. It baffled me. There's no way when the engine is off, key is in ignition, (coils are dissconnected aswell), also my sound system was dissconnected (I don't run any audio capacitors), battery reads 12.2v and with the 10amp fuse blown I was measuring 24 to 30v. The reading would move a bit from 30v to 24v which was weird. I took a pic of the multi meter reading 🤣: (This is a brand new single channel digital oscilloscope that also has a multi meter mode). Before when the fuse was blown, I had one lead on the 12v supply (green/white wires) of that brown relay and the other lead on the negative battery terminal. When I turned the key on ignition (engine off), it would read 30v. Then when I removed that relay from it's plug and tried putting ignition on again, it would read 12v, but I think it's because it can't turn on the ecu now that I removed it. I asked Chatgpt and this is what it had to say: Not sure if those theories would be possible but, any auto sparkies here? welcome to confirm. 🤷‍♂️ No idea, but if it happens again, atleast I know what type of issue it is, unlike last few months where I didn't know what was causing all my issues and I was just taking stabs in the dark to figure out what type of problem it was. If it does happen again I'm going to investigate futher and trace back the source even more and inspect more circuits. I drove it to work this morning and the car drove and boosted fine. Yeah I was thinking the same, so I've imported my back up saved map (which is the map that I saved when it got done tuning) back onto my haltech with the base fuel pressure set to 43.5psi.

Bit of a late reply here as me and my wife have been really busy with new born twins. I finally got these issues fixed and it was something really stupid that caused all of this 🤦‍♂️... After alot of mucking around with trying to figure out what is causing these issues, I back probed one of the R35 coils on the power 12v supply, with the engine running it got 25v! And I thought, hang on..., this isn't normal. Measured my battery with the engine running to check for over charge from the alternator and it wasn't that. So then I dissconnected the R35 PRP coil harness and backprobed the power supply on the engine loom where the ignition coil harness connects, with the key on ignition (engine off) it measured 30v! So then I had to trace where that high voltage was coming from and it lead me to the brown relay "ECM & IGN coil relay" inside the cabin next to the ECU on the passanger wall. This relay feeds power to the ECM and ignition coils. Tried swapping it with another same relay. nah still 30v.. coming from the 2 green/white wires in the brown relay. So then I set my multi meter to the beep continuity mode and probed every fuse on the fuse box inside the cabin to try and find this high voltage power source. Wasn't any of the fuses inside the cabin. Then probed all the fuses in the engine bay and BAM, got my power source that was a 10AMP fuse called "ENG CONT". Pulled the fuse out, and what do you know... it was blown. 🤦‍♂️ So then I quickly replaced it with a new 10AMP fuse, started the car and yeah haha [insert extreme face palm]... The RPM blimping thing went away, car idles smoothly now like what it was before. I swear! I checked all my fuses with my test light twice before I created this forum thread. I think, maybe because one side of that faulty 10A fuse lit up on my test light, I must have thought it was still ok and not blown. But now I know to have both sides light up on the test light when checking fuses... I hate diagnosing electricals.... I'd take mechanical problems over electrical problems any day🤣. Drove the car around my suburb with the engine up to operating temp and it runs fine like before. However, I notice that my fuel pressure is still at 49psi. So I'm thinking this must be normal for my system as I've upgraded the stock fuel pump to a Walbro 255L/h with a constant 12v mod. But anyway, I'm just glad to have my daily back on the road! Thanks everyone for the replies on this thread, all sorted now! One thing I want to ask you tuner guys, my base fuel pressure on the haltech main settings are set to 43.5psi from default (my tuner must have not checked the fuel pressure maybe when tuning my car?). Do I set it to what it actually is idling on at 49psi? Or just leave it ("if it aint broke, don't fix it/leave it")?

Yeah, after my first post i did notice that my tps wasn't calibrated exactly to the tee. So I did calibrate it: applied the settings, rebooted ecu and it's still the same.

Yeah I think i did jab it twice.

Update on this situation: (Forgot to put in my previous post that I bought another brand new pressure gauge and fuel shows the same 50psi) I've deleted all the aftermarket immobilizers and turbo timer shyt and placed all factory wiring back to normal. The problem is still the same and nothing changed, but atleast it's a bit more tidier under the steering wheel. I've also siphoned out all the old fuel and then poured new batch of BP98 fuel (about 15L) into the tank. Nothing changed. Still the same idle. I also changed out the MAP vac line with a new one and, still the same. So 2 days ago, I thought fk it. I'll just change out the fuel rail and injectors with another set that I know worked well in my brother's R34 a while back. That other fuel rail has the exact same Xspurt 640cc as what I have right now. So I changed it out to that other fuel rail and injectors (new O-rings) and injector harness. Put everything back together, started the engine, 464906286_1624569924763105_5179888796065901094_n.mp4 and yeah... still the same 50psi and idle problem. 🫠 I can also hear each of injector's solenoids running when I put a screw driver to it and have the other end to my ear. I might get a noid light just to confirm pulsasion but yeah, very strange that both fuel rails and injectors put out 50psi. 31-10-2024.csv I've attached it here. I started recording, then started the engine and let it idle with no throttle, then at the end I applied a little throttle and then stopped recording. So, now idk. I'm going to see if swapping out the brand new R35 coils to my old splits fires will change anything. 🤷‍♂️

Thanks everyone for the replies/suggestions on my issue here. I'm still trying to diagnose the root cause of this. Things I have done so far: A week ago, I disconnected my 12v constant relay mod and returned it to the stock FPCM wiring: I could hear the sound of the fuel priming was different because of the FPCM limiting the amount of volts going to the fuel pump. From memory I think it also primed to 43psi. It was very hard to start it. I don't think from memory I could start it at all. I had to then ground the fuel pump to the chassie and then it could start after a couple of cranks. Fuel pressure did drop a bit to about 45psi (i think). It was idling even worse than before. 🤔 It was also doing the same weird RPM tacho thing. So I've returned it back to the constant 12v relay mod for now as I investigate more. Right now, I'm in the process of deleting my aftermarket immobilizer, an old Japanese turbo timer, and another aftermarket transponder immobilizer that the previous owners put in years ago (from sexspec days). Just curious to see if this whole bird nest would cause some weird electrical problems. The Viper 5900 immobilizer stopped working a few years ago, and I pulled out the main fuse on it years ago to stop it from being a parasitic battery drain and I haven't bothered to clean up the mess there, so now is a good time to. There was a RPM signal wire that spliced into the RPM tacho signal from the ECU harness. I've taken it out. I've already pulled out the Viper immobilizer and returned all the joints wires/splices back to factory. I let the car idle and it's still the same idle and RPM tacho idle issue. Now I'm going to delete the turbo timer and the other key transponder immobilizer (autowatch) and return splicing/wiring back to factory setup. Just to see if this might be causing some electrical issues. It might not, but I just want to get rid of it anyway. True!, I was actually thinking this the other day. I will check with another new vac line to make sure this is not the issue. This is actually on my to-do list, and you might be right, this might be a shit batch of fuel because I filled the tank up to 3/4 full from near empty, then I went to the shops and it happened straight after that. I've always filled up from this servo for years with no problems, but yeah might be my first batch ever batch of shit fuel from them. Will be doing this next when I get my hands on a container/jerry can. I just didn't think to do this straight away because it doesn't really explain why the tacho RPM thing is happening. Maybe I'll chuck some injector cleaner in the new batch too?

I would need one of these adpaters to by-pass the factory dampner: Which I don't have here atm. So I'm just going to have to bite the bullet and take out the fuel rail and inspec it. And I'll put the other spare one in, do a fuel pressure test with top half of the stock manifold off. (^from google images) If the pressure is still high, I can plumb the gauge maybe in there (circled in red) to check for the pressure after the dampner. Can't do it with the top half of the manifold in the way.

Yeah, I was just trying to show on camera that the manifold is pulling enough vacuum through that hose to pull the diaphram in the stock fpr but couldn't really hear it on film. Yeah, it's strange. Fuel should be by-passing through the reg to exit back into the tank thus reducing the fuel pressure: Sorry for my awful drawing here (I like to make diagrams to understand it better 🤪) The (temporary) fuel gauge is plumbed between the fuel filter and dampner. I've already eliminated the possible cause of restriction that the return line might have had and it's not that because I placed a long hose from the FPR (exit from the fuel rail), by-passing the 2nd dampner and return line, then straight into the filler fuel cap (as seen on my first vid). And it was still at 50 psi. Which means that I have a fuel restriction between the 1st dampner and the FPR. Possible causes: Blockage/restiction in the 1st dampner: I know it's not this because I've swapped it out to a known working one from a spare complete neo engine sitting in the shed. Blockage/restiction in the Fuel Pressure Regulator (FPR): Also, can't be this because I swapped it out to a known working one from the other engine. Blockage/restriction in the fuel rail and fuel rail's lines: this could probably be the case. Maybe red rubber grease got in there when I changed the injectors (with new seals) a year ago? Who knows. The only way to know is if I take the bastard off and inspect it (or swap it to the other spare one), which I think I will just have to do. Injectors causing a restriction in fuel causing high pressure? Could this be? I wouldn't think so? Because even if injectors were completely blocked, fuel would just by-pass them through to the FPR and exit? Let me know if I'm wrong though. Because if that's the case, it could explain some weird electrical shit where the injectors aren't opening enough or something. Air bubbles in fuel rail? Can this be a thing? Could air get trapped inside the fuel rail and cause high pressure? Shouldn't though right? Faulty pressure gauge? I just grabbed this old pressure gauge that was sitting in our toolbox at work. I'm going to buy another gauge and see if I get the same result just incase. But it reads the priming correctly at 40ish psi. idk... The spare rb25det neo engine that we have in the shed came out of my brother's R34 that was working perfectly fine before we pulled it out to slap a rb30/25det neo in there. It also has the same xsprut 640cc injectors on the fuel rail still. So I might have to swap them out and see what it does. 😮‍💨

This is the first time I've checked my fuel pressure and I've got no idea what the pressure was before this. So I'm not sure if this is 100% the true cause of my idling problems atm, but this high pressure is my first clue to something that is "out of spec" according to the workshop manual. Also, you can see in the video, the haltech tries to get the afr target and it does maintain it at 14.2. So I would assume the afr is fine? I have to dissagree with the cluster comment. I don't think it's a bad solder joint. There's nothing wrong with my Nismo cluster because I swapped out the cluster to my old nissan one and it does the same rpm glitchy thing. So to me, thats the signal coming from the ecu that is farked. I bet if i were to put both those clusters in a working r34 gtt, it would work as it should. I just took this video now to show what happens to the fuel pressure when I remove the vac lines on both the FPR and damper. It remains at 50psi: Can definitly feel theres vacuum. No aftermarket reg, just stock one. I reckon its the signal coming from the ecu. So correct me if im wrong, cas send signal to ecu to show rpm of engine (and thats what we see on the haltech software) then ecu sends out ignition and injector pulses ect ect, and then spits out a signal for the rpm gauge on the cluster? Makes me wonder if something in the injectors electrically (solenoids?) or something is causing some weird feedback to the cluster signal. Yes! They did. And I also think they are related/connected to this idle issue. Haha sorry about it. I just filmed it with my phone. Let me know if you want me to get something els specific on vid. Yeah it's really odd. I would like to try and diagnose the injector wiring next. Don't know if that requires an oscilloscope?

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

[Update] I've finally got around putting a bigger turbo on and I also swapped the leaking vct head with a different head that i didn't weld this time! 🤣 Just drilled and tapped the head for the external vct feed. Theres plenty of meat. I don't know why I got the other one welded. I think when i did all my research on this, i did see someone say that you have to add more meat on for the threads. Oh well. New head is running good! No leaks at all. I actually bought this other Neo head 2 years ago from gumtree complete with valve train already machined because my intake cam gear's rear bolts loosened over time and one of them rattled loosely inside my timing belt then eventually broke the intake gear. Luckly i was just leaving for work driving slowly up our street and the car just shat its self and turned off. I had to push it back home and found out what happened. So i instantly thought the valves must have kissed the pistons and thus why i bought another head. After i replaced the intake cam with another one, i tested the compression and it was still fine. Also ran fine and ive been driving like this for ages. I recently took that old head off and saw no damage to the valves or pistons. So then i just cleaned all the old gasket off, gave the surface a bit of a hone with oil stone and put new nissan head gasket on, placed the other head on, and everything els. I went with a Hypergear ATR45 .82 rear ball bearing turbo with a Turbosmart 45mm external wastegate that Hypergear welded onto the rear turbo housing and then plumbs back into the dump pipe. I also upgraded the coils to PRP R35 coil kit. I then went to get it tuned and made 367hp. Tuner said straight away, the Z32 maf and nistune is now the restriction and i will be going Haltech soon. The engine has now done 41000kms and its going f#ck!n mint. No leaks at all now. My little brother also has a R34 GTT. We also did the exact same RB30 bottom end swap like i did. He also has the exact same mods that i have except he has Haltech platinum pro and his made 415hp and hes loving it.

Ah ok haha. there you go. I work in a plastic injection moulding factory and I was looking at our big industrial water chillers that cools our mould dies and machines and thought, hmmmm imagine if you could have a mini chiller in your car that could cool a water to air intercooler. And I thought I was on to something. Googled chillers on engines and FI Interchillers came up and thought, holy shit, whys no one using these more on other engines. Even looking at this video made me tempting to try one: I would never buy one of the FI interchillers (waayyy to expensive for trying something like this). I'll always stick to my a2a. That's why I just wanted to check if anyone has tried this with success so I could try and make my own chiller maybe. There's just not much info on a chiller+water to air setup. Would be a good video for someone to do on 😉

Has anyone tried chillers with an water to air cooler on their RBs instead of air to air intercoolers? I know there has been some people that have tried the water to air intercoolers with the water/coolant running into a seperate radiator with fan and then that water/coolant runs through the water to air intercooler via a pump. Some has said that there were problems with this setup, one of them being heat soak. And they don't really make a difference compared to air to air, or it wasn't really worth it the money? But, has anyone tried this setup with a chiller instead the water being cooled in a radiator+fan? There is a company called FI Chillers that make chillers for supercharged and turbo drag cars. Mainly for hellcats, holdens and other v8s... They explain it better on their website: https://fiinterchillers.com/tech_articles/how-does-a-universal-interchiller-kit-adapt-to-my-car/ The chiller mounts somewhere (anywhere), water (AC Delco 50/50 anti freeze recommended) flows from a reservoir into the chiller via a pump then into a water to air intercooler and back to the reservoir. The chiller is cooled with refrigerant gas by tapping into your exsisting AC system. Doesn't sound too complicated? Alot of the guys that run these chillers rave about how low their IAT are. Just curious if anyone has tried this on their RB's or any jap related turbo engine? (Mainly daily/street use) Wanted to see what kind of gains you could see and/or feel with a setup like this.

*Wanting to buy* RB25DET Neo cylinder head complete or bare. Let me know if you have one for sale thanks.

Thanks! I've heard some guys on here have gotten away with the stock R34 GTT bonnet. Mine is aftermarket (Z-tune fiberglass i think?) that has fins pointing towards the engine and they did foul on the stock intake plenum and throttle body aswell as the intercooler pipe running over the fan and it couldn't close. Because it was fiberglass, I just grabbed a dremal and hacked away on the under side of the bonnet to make it close. It barely closes now and is still rubbing on my intake plenum and pipe. These Z-tune bonnets come with a tray under the fins so that you don't get rain dripping on your engine. I can't run that tray so I just use aluminium tape to close the fins. I wish I could go FFP, only for the clearance and ease of service but they are out of my budget. The engine is now on the 10000kms mark. Been using the car everyday to and from work. Hasn't had any issues yet. Running mint as ?. There is still a little oil leak coming from that f*c@ing!!! external shitty VCT weld which is causing my belts to be a bit oily which is not good for the timing belt. But it doesn't drain my oil under the dip stick mark before the next service. I will have to replace it and see what I can do with the leak some time. It really feels like it needs a bigger turbo. I can't wait to get a new one. I was thinking of hypergear's ATR45 BB? Just a simple bolt on to stock rb25 mani.