lymon

http://www.twinturbo.net/nissan/300zx/forums/main/view/1133844/More-gauge-cluster-repair-info.html As a last resort, if you are out of options and don't want to buy a brandnew and very costly speedo from Nissan: this same guy on the US-forum ("DVDburn") can refurbish speedo's with all new components.

This may be a shot in the dark, but recently has been discovered that some of the cheap (ebay/chinese) consult cables short the vss signal pin (in the consult-plug), resulting in a non working speedo/hicas/power-steering and other related issues caused by a missing speed signal

(oil) contamination has nothing to do with it...the oil can not get to the "electronics" inside the sender and/or damage it in any other way. the oil-pressure will push a small lever which makes 2 small contact-arms slide over a variable resistor-wire. Over time these contact-arms get bend slightly out of spec and it will loose contact with the resistor-wire. By simply bending the arm(s) back and clean the resistor-wire with contact cleaner, you can restore the sender and it will work fine again. I have disassembled and rebuild/repaired several oil-pressure senders this way. In the picture below you can see how it works, the contact-arms (yellow circles) slide over the resistor wire (red arrow) which will send the signal to the gauge in the dashboard.

probably caused by dried/cracked solder joints on the circuitboard of the speedo You can fix this by resoldering (preferably all) solder joints on the board with a fine/precision soldering iron

fill up the fueltank and then (re)move needle to full to full mark.

do you still have the standard recirculation valves in place ? if so, one or both may be leaking internally and this won't show up in a boost leak test.

http://300zx-twinturbo.com/cgi-bin/manual.cgi?list=efec&dir=&config=&refresh=&direction=forward&scale=0&cycle=off&slide=111&design=default&total=190

The 94 factory alarm is a completely different system, so I wouldn't use that schematic for this system. You could try to find the GND wire by using a multimeter and measuring the resistance between the (metal) housing or black wire and each of the 4 unknown wires. The GND wire should be (very close to) 0 Ohm looking closer at your schematic, it looks like one of the horns is in parallel with the lever unit, so it will probably honk when the the door is remotely open or close. The other horn is in parallel with the IR-sensor and I'm not sure what effect this has. Maybe you can post a few pictures of the circuit board inside the main module (pref. top and bottom of the board), maybe that will make things more clear

Ok, so if I understand correctly both speedo and signal from speedo (to HICAS ECU, which controls the powersteering) were fixed, otherwise the heavy power steering problem would have still been there. Now speedo (signal) has gone again even with another cluster. In that case I would have a look or replace the speedsensor (in the gearbox) or trace/check the signalwire from the speedsensor to the speedo. The boostgauge pinned to the right could be a disconnected or faulty boostsensor (under the bonnet) or also a broken wire at the back of the cluster this may help to trace/find the wires you need: http://300zx-twinturbo.com/cgi-bin/manual.cgi?list=el&dir=&config=&refresh=&direction=forward&scale=0&cycle=off&slide=66&design=default&total=133

What happens if you disconnect that extra/new wire that you mention?

also, if it's an alarm (otherwise I wouldn't know what the horns are used for), it needs at least a sensor/switch wire, eg. connected to the interior light (module) to detect a door was opened or something.

I am missing the power feed lines in your schematic (+ 12V and GND) ? my guess is the red wire is for +12V (switched), the yellow one for a constant +12V the brown one for GND and green one for hazards or some sort of warning light on the dashboard to indicate the system is armed. without a (factory) schematic this will remain a wild guess though Although you can open up the main control module and usually see or find out which connections/pins are used for GND and power. And in some cases the pins are named on the board

Only rear calipers that are a straight fit are the Brembo's from the R33 GTR and R34 GTR

the oil check-valves and orifices for the heads are mounted in the block deck and is not something you can get to easily...it requires removal of the heads. oil pressure in the rest of the block is probably fine, otherwise the engine would have seized by now. A very good engine flush (eg. with a combo of diesel + acetone) may work things loose, but it can also make things (much) worse This kind of flush is best left to a specialist so it can be done in a controlled way and aborted as soon as any other noises/damage start to surface.

Most likely a blocked or faulty check ball/valve in the block...I wouldn't drive the car anymore until you have a good diagnosis done by someone that knows these engines. read this: http://www.300zx.co.uk/forums/showthread.php?171717-head-oil-starvation-or-just-faulty-lifters

just realized I made a mistake...I had RHD/LHD mixed up. Anyway.. in a RHD car, that connector should most likely be connected to the FPR-control solenoid (the solenoid at the right of your hand in 1st picture) This solenoid can be bypassed without any issues, although in that case it's best to "loop" the fpr lines as you can see in this picture: The hose could be from a number of things though...it could be from the FPR solenoid, the AIV system or the boost-sensor (if the boost dial on your dashboard doesn't work, then the hose is from this sensor) if you start the engine and let it idle and there's no hissing noise from this hose, then it probably won't do much harm to leave it disconnected. But you could check where the other end of the hose is connected to, to figure out what it is for and what it is supposed to be connected to.

connector is probably of the AIV or EGR solenoid (in first picture you can see one of these solenoids at the right of your hand) The hose should probably also connect to one of these solenoids...I guess AIV-soleoid, but looks a bit unclear as to where it originates from in the picture. Both AIV and EGR are there for emission improvement purposes and won't really do any harm when not connected or disabled. The engine will run fine without it.

when you replaced the fuelpump, did you use special submersible fuelhose to connect the pump to the mount ? regular fuelhose can not be used,as it will quickly degrade inside a fueltank and will rupture or fall apart.

High ambient temperatures should not cause a clutch to slip, as it is supposed to cope with much higher temperatures. More likely causes can be: oil (eg. from a leaking rear main seal or gearbox seal), an incorrect adjusted clutch-pedal, a burned out or over-skimmed flywheel or bad quality clutch (eg. most ebay clutches).

3 inch for GT25R's will help but not a lot. These turbos are only marginally larger then standard turbos and too small to boost a (consistent) 20+ psi at higher revs. You can try to adjust the wastegate actuator arms to have it hold a little bit more, but the actuator of RH turbo will be near impossible to adjust with the engine in the car. Also ideally you will need to adjust the actuators to open at more or less the same amount of pressure. A (true) dual intake, with a pair of good flowing airfilters should help get you a bit more power out of these turbos.

It's a digital signal (0-5v square wave), so if you have a scope you should be able to see this waveform/signal on the Y/G wire. you can try to remove the mph converter and see if it works then or try a different cluster

the actual (digital) speed signal for Engine ECU, HICAS ECU and ATCU comes from the speedometer-cluster and not from the sensor directly. so if you have a working speedometer, but no speed-indication on any of the ECU's (which indeed are the cause for the HICAS problems and when slowing down), you will have to look at the speedometer (cluster) Maybe someone installed a faulty mph converter or something..

the valve solenoids are inside the gearbox and you will need to remove the oilpan (and probably the lower valve body..can't remember) to get to the main connectors and solenoids putting 12v on the terminals should make the solenoids "click" Maybe best to try another ATCU first, before taking apart the gearbox. the VHCL/S SE-MTR is the speed sensor on the side of the gearbox. However if your speedometer is working correctly, it is probably not the sensor itself but something else, as it uses the same speed sensor. When you monitor the engine ECU using conzult, does the speed reading work correctly there ?

sounds like a wiring issue. Are all 3 connectors from the main AT harness plugged in (firmly) ?

a new viscous fan clutch is a lot less then then the electric fan + special shroud you mentioned. no where near the 300 GBP you were quoted. https://conceptzperformance.com/Cart/description.php?II=957