DatsunBanana

Nice! That makes perfect sense now - thanks 👍

Couldn't quite see what you mean from your photos, can you share a pic of the drilled hole and spacer? Still promising myself that one day I'll fit all the manual bits I've got in the garage. Is the rusty one the R33 pedal?

You may have already seen it but there's been a bit more discussion on this and the other valves (swirl valves) in the NA RB20 and 25 NEO differences thread in the Naturally Aspirated Performance forum. When I posted above I was still trying to decide what to do. I've been running 5 years now with the hose just disconnected from the diaphragm and all runs really well. You've got me thinking again about trying to connect a boost/vacuum line from the plenum now to see if there's any noticeable difference.

That 'pump' is a vacuum tank, I guess just a reservoir for holding the vacuum. On the 20DE looks like it's used for both the swirl and torque butterflies. One line is to the plenum and the other two will go to your torque valve solenoid and swirl solenoid. The solenoids will have their own lines to the actuators. The solenoids seem to switch the actuator hose to either the vacuum tank or the air filter side of the throttle body. This is from page EC-3 in the manual. On 25DE the tank is just for the torque valve so I binned that and the solenoid and related hoses and used the old tank take-off for my boost gauge I think. From experience I know the torque valve is under spring pressure keeping it in the default open position. I don't know about the swirl valves but if they are sprung to open position then removing the vacuum tank, solenoid and hoses from the actuator would (I'm guessing here) let them spring quite firmly open (??) Page EC-44 in the manual gives info on the RPM threshold for the solenoid ON/OFF signal.

The main torque valve shouldn't need hacking as it defaults to open without the vacuum pipe connected (at least on the 25DE). Not sure about the swirl valves but in your pic they look open by default. On the 25DE I used a GTT ECU but it doesn't have the signal to control the valve. Other discussions seem to suggest at boost the valves won't do much but would still be cool to know what it's like controlled by an aftermarket ECU.

Have you tried Conceptua tuning on eBay? They have a few options for 33 gtst. Great to deal with too.

I was always of the same opinion as Kinkstaah that using a GTT auto ECU would be complicated. If you've got the R34 service manual, pages EC11/12 show that GT auto and manual have the same ECU wiring that uses a separate transmission control unit and the GTT auto has the transmission control built in to it. Page AT3 states that plainly. As per the diagrams, wiring for manual GTT ECU is same as GT auto/manual so that's what I used on my auto NA+t. It works fine and just uses the original GT transmission control unit to look after the auto box. As mentioned above, popular opinion is that there could be problems if the transmission circuit inside the GTT auto ECU creates conflict or doesn't talk with the GT transmission control unit still in the car. Pages EC13/14 will show you which pins are different and what they control. On page EC11, pin 79 of a GTT auto ECU (multiplex communication) is shown as only being for TCS/ABS but on page EC12 for non-turbo it also goes to the separate GT TCU. Pages AT8/9 have the transmission circuit diagrams (top right corner on page AT9 shows the connections from separate TCU to ECU). If you're gonna give it a go, those refs might help and if you get it working report back to feed the knowledge base. R34Nur posted a couple of weeks ago and said it worked fine with auto GTT ECU but that does go against popular opinion.

When I did this few years back I read everything I could find on the subject including the thread here for example: I was happy to give it a go based on Dan666's experience but only after I checked out EC-11,12,13,14 and AT-8,9 in the workshop manual for myself. As I understand it, the required signals will still be connected between the manual GTT ECU and the existing separate TCU via the GT loom (e.g. pin 29 speed signal and pin 37 throttle opening signal). I'd suggest to anyone planning this swap to look at those pages and get an idea of the similarities and differences. Apart from that I can only speak from experience - I swapped in the manual GTT ECU and it's been fine on my NA+t. I said 'almost' plug and play because there will be errors related to traction control and boost sensor which aren't physically there on a GT. But those were easy enough to workaround - I fed suitable voltages to the correct pins on the ECU via diodes to stop the check engine light coming on. Pin 104 signal has different purposes between GT/GTT ECUs so a GTT ECU won't control the GT inlet manifold valve if that's still fitted. Little bit of info on page EC-44 for anyone interested. The signals for A/T position indicator dash lights are not present on the manual GT ECU. Mine never worked before I did the conversion so I can't say for sure what will happen to those but I don't see why they wouldn't get the signals from the existing GT TCU. Pin 79 is an interesting one. Looking at page EC-18, that signal relates to malfunction detection. For GTT it relates to TCS/ABS e.g. 'Malfunction (open/short circuit, etc.) is detected in multiplex communication line between engine and TCS/ABS'. And for GT it's different: Malfunction (open circuit, short circuit, etc.) is detected in multiplex communication line between ECM and TCM. [RB25DE). That difference hasn't caused any issues for me in the past 4 years as a daily driver. For anyone Googling for answers I'd say some of us have had success and some haven't. It's inconclusive. But for the OP who's invested in this already, a manual GTT ECU can work and might be worth a try compared to the GTT auto ECU which will be a pain for the reasons already pointed out.

You could just try and sell the auto ECU, keep the Nistune and put it in a GTT manual ECU. That will allow the existing NA TCU and wiring to run the gearbox. That's what I've got on my NA+t and is 'almost' plug and play. It won't be a GTT but it'll get you to the next step of sorting out the map.

This article appears to be talking about the swirl valves ... https://carscanners.net/nissan-skyline-r34-and-laurel-c35-with-rb20-de-neo/ And this is one of the old discussions with dead pic links. https://www.skylineowners.com/threads/rb20de-r34-gtt-neo-engine.155290/

Back to your original question, the RB20DE NEO has butterfly valves for swirl (see page EC-3 in the R34 manual). I remember seeing some pics once but so many pics have dead links now I can only find the discussions by googling. So I can't remember exactly where the valves are - in the runners maybe? The RB25DE NEO doesn't have them although both have the variable air intake butterfly valve in the inlet plenum.

I'm running a stock NEO non-turbo AFM without any problems. I'm using GTT injectors and stock GTT ECU. At first I kept the NGK BKR5EIX iridium plugs that I already had before the turbo conversion. Not ideal maybe but they worked ok. I've been running the conversion for 3 or 4 years. Recently I did have a misfire that felt a bit like hitting the rev limiter. I found some Splitfire coil packs on a spare engine I have so fitted those. At the same time I changed to NGK BKR7ESC-11 that one of the tuners here in the UK recommended for my +t and that misfire is gone.

I'm sure someone will come up with a better suggestion more local to you but here in the UK, Conceptua are a reputable dealer who stock these for the non-turbo intake and will post worldwide ... https://www.ebay.co.uk/itm/New-Throttle-Body-to-Plenum-Specs-Gasket-For-R34-GT-Skyline-RB25DE-Neo/111878477184?hash=item1a0c7a1580:g:5D4AAOSwoydWnOLe Alternatively use https://nissan.epc-data.com/skyline to find your model and in the engine and fuel system section find the manifold gasket and click through to the amayama shop and have it delivered from Japan. I've had stuff sent to the UK this way no problem. Import tax and waiting a couple of weeks is a pain though. But I thought you guys over there can buy most stuff off the shelf?

Fuel filter made no difference. I might just let it go now and not worry about it as the issue is negligible. Or if I can be bothered I might check the pump is still mounted in the tank ok and might swap the AAC for my spare cos years ago I lost the spring while cleaning it and replaced it with one from a ball point pen ? Anyway re. the direct voltage conversion, I checked the wiring diagram and thought I'd post this in case anyone else is interested. I believe that stock GT wiring will run the fuel pump at 13.5V as standard. In the attached wiring diagram, red lines I've marked are all battery voltage from the ignition switch and I've taken a confirmed reading of 13.5V at the solenoid plug I've marked. The fuel pump dropping resistor (and control module) don't exist on the non-turbo so the other side of the pump is direct to ground (green line on diagram). So although I haven't measured it directly at the pump, I reckon that means a non-turbo car will already have full battery voltage at the pump. Happy to be corrected if I'm wrong though.

Interesting point about the pump. Here's a pic from another thread showing what I had to do to mount it in the cradle. I think a Walbro 342 would have fitted better than a 341 but I tried to make sure it was secure. But in theory the hose clip could have slipped and who knows! Maybe I'll check that. Ordered a fuel filter too as it's about time I changed that.

Yep stock GTT injectors and ECU on a DE+t conversion. Would the two stage fuel pump relay even exist on what was originally an NA car? By the way, the PCV hose was split at the inlet end. Swapped that and the grommet in the cam cover but it's made no difference. At least I know that's done now though. What about the AAC valve ... anything in there that could flop about on a slope and cause rough idling? Any other ideas are welcome ?

Thanks for the replies. I'll have a look at the PCV valve and hoses etc. but yeah, it's not a major worry ... I'm still smiling at finding a 'free' set of splitfires ?

Had an interesting couple of days. Have had a high revs misfire and rough idle but without any error codes on my R34 (RB25DE+t). Had some used Benchmark coil packs already so fitted those plus brand new plugs which fixed the high revs issue but still had rough idle and now it started throwing code 21. It felt like failing (but not completely failed) coil pack misfire so started swapping one at a time for one of the original coil packs (hoping I was using a good one) but still getting rough idle and code 21. Revs above idle were smooth. I tried Datascan to switch off cylinders but couldn't narrow it down. Decided at that point I may as well try changing the coil pack loom as I've had a spare engine sitting in the corner of the garage for a couple of years. I whipped off the cover and to my delight found a set of Splitfires. Fitted those and the loom but it was still idling rough (but at least no code 21 anymore). Took it out on the road and it drove lovely. Stopped at the side of the road and the idle was smooth as anything. Got home onto the driveway and it was rough again. Started wondering if my steep upwards sloping driveway might have been causing the rough idle all along. Although it seemed like a crazy idea I drove back onto the road ... smooth idle. Back up the driveway ... rough idle. Repeated a half dozen times and it consistently idles rough with the nose pointed up the drive and idles smooth on the flat. Anyone ever heard of anything like that before? All I can think of is fuel pressure. I've got a Walbro but I got that second hand so could be tired. I've been doing these tests with 3/4 to 1/2 tank of petrol but could that moving to the back of the tank affect pressure? And why would it be fine at anything above idle? Any other components or internals that could be affected by an upwards incline? Oh and from a cold start, for the first few seconds it's quite smooth till the revs settle a bit then the rough idle becomes noticeable. It's roughest while cold but less so when it's warmed up.

Sorry can't answer your question but my R34 auto also came with none of those dash lights working. Didn't give it a thought until I saw a video online showing one with lights working. I couldn't find any info anywhere by searching either but I wondered if it's a thing for people to pull a fuse if they don't like the lights?? Mine also didn't have the lights working on the centre console but that was just bulbs so I changed those.

Nissan Datascan software has some of what you want but won't show pressures. It'll give you most other sensors though and has some useful diagnostic features. I sometimes use it on a cheap 8" Windows 10 tablet with a bluetooth dongle in the consult connector and charge off a USB cigarette lighter adapter. I just velcro it to a removable block of wood that slips tightly into the slot/tray below my single din stereo. No fancy on/off control though. There's also a lite android version of NDS which should work nicely with a double din android head unit instead of customising the dashboard.

Here's a summary from my experience and from the other guys who posted in this thread - and before that from reading 666Dan's legendary thread (many times) and others on this subject. I know it's a lot to take in and I remember that I still had a few questions I just needed some reassurance on. Assuming you've put GTT injectors on, you can run a standard GTT manual ECU (it'll work on the auto or manual). You can always nistune it later but until then keep the boost at actuator pressure - about 6-7 psi. If you use the standard R34 DE Y-pipe inlet, disconnect the butterfly valve plug cos the GTT ECU will send different signals on that pin. You'll have to tee into the pipes somewhere for the turbo water return and you'll have to make some custom j-pipe solution. I've done this without changing the loom at all. If you want to try the R33 inlet you need to search for what to do about the throttle body and idle control plugs as pretty sure there is some difference. That's where loom changes might be needed but maybe not if you swap the correct R34 parts onto the R33 inlet. You won't have to tee into pipes for water return cos its on the back of the inlet. There's nothing for the butterfly plug to connect to so leave it loose. All the standard R33 IC and inlet piping should fit so no custom work for that. The larger ports on the plenum will meet a restriction against the smaller NEO DE head ports but my opinion is that who cares about airflow not being perfect when you've just gained a load of boost. If you want to use the Greddy/Freddy I think that's a lot of work anyway even doing it to a standard turbo car so probably even more research needed there. Loom changes might be needed for this but not entirely sure.

Just wondering if this is normal ... if I lift the lower part of the drivers side wiper arm it rises by a good inch as seen in the pictures attached. It feels like it's against spring pressure somewhere under the scuttle panel where the motor is. I think it must be right to allow for the wiper angle to change as it comes up the windscreen but thought I'd ask in case it's the reason for my squeaky wipers. Thanks.

Did you get this sorted? If not I'll try and remember exactly what I did ?

I think like Kiwi says if you have the R33 stuff you may as well use all that but I think the throttle body electrical plugs might be different which is why you'd use the R34 one. Someone will correct me if I'm wrong. The R33 turbo plenum has some advantages ... ports are bigger although I don't remember if the DE head ports match that size. Good thing is it will have a water return hose fitting on the back and I would imagine it's easier to get at spark plugs and coil packs when you don't have to remove the y-pipe every time. Plus if you're changing injectors you have to take it all off anyway so may aswell change it. Having said that I just kept the R34 y-pipe and disabled the butterfly. It closes with vacuum pressure so when disconnected it will open up the plenum anyway.

If you've got an R34 non-turbo then you can fit brakes from other models but you have to do caliper and discs together unless you have some sort of bracket to change the distance of the caliper from the disc. I would also be inclined to do a full set not just rears as mentioned above. I swapped out the smaller discs and slider style calipers on my R34 GT for a full set from an R32 GTR. Most (maybe all) R34 non-turbo models will have a 14mm bolt and therefore a 14mm hole in the mounting. If you swap for brakes from an R32 or R33 they'll have a 12mm bolt you'll and will have a 12mm thread in the caliper. You keep the 12mm bolt and just put a stainless steel sleeve in the mounting hole (14mm outside diameter with a 1mm wall thickness). The mounting hole centres line up perfectly. Braided lines would be sensible too. I haven't had any braking problems or hydraulic imbalance but some say to change the master cylinder as well to match the bias needed for the brakes you use. You also have to cut the lip off the backplate/dust-shield or change them for bigger ones to match the discs you use. I cut mine. If you use brake lines with banjos then you may need to cut the banjo bolt a little shorter.