RB25 injectors not ticking but has fuel pressure, good spark and good compression

[Raipe]

So my problem is that my car wont start. Injectors are not ticking while spinning the CAS but i can feel a small tick while cranking it. I tested the CAS with another one from a skyline which is working properly but it didint help. I also tested my cas in the other skyline, it worked fine so the CAS should be ok. Resistance of all injectors is 11.4 ohm, and they get 12.4v continuous but weak pulse voltage? While cranking the car, the other wire gets only 0.06v. Im not sure is it the pulse wire/voltage tho but it is the another wire of the two wires. Fuel pump starts working while spinning the CAS and gets good spark on every plug. The car was running fine earlier today but suddenly it wont start anymore. Could something be wrong with the injectors wiring or something else like an fuse or relay? So what should i check next? -R32 gtst Skyline 1992 with swapped RB25 and nistune ecu.

[GTSBoy]

The injectors have constant 12V on one side and the ECU switches the other side to earth to provide the ON. So, you should have 12V on both sides of the injector when nothing is happening, and the ECU side should drop to low voltage when they are pulsed. You won't see this happening on a DMM. Not fast enough. You'd need an analogue multimeter or an oscilloscope to see that. You can also get a noid light to plug into the injector plug and see if it turns on. It's amazing what you can do with old skool tech.

You can work out which wire is supposed to be which, because all 6 injectors have power fed from the same place and the other 6 wires go back to the ECU.

You really need to know if the ECU is pulsing the injectors properly. If it is, and they are not doing anything, then you have to start looking at what's wrong with the injectors/fuel system.

 

[Raipe]

Thank you sir! Ill test them tomorrow and i will post the results right away. So i can check the injector pulse also by hooking up an test light into battery positive and the other end to injectors wire one by one? If it grounds so the test light would blink fast as i understood. And the same thing from the ECUs pins to be sure that the ECU is pulsing them overall? 

[KiwiRS4T]

Had a thought but dismissed it on second thoughts!

[Raipe]

Ill check the CAS wires! I am not sure that all the wires are ok in there but the mechanical connection between camshaft and CAS is fine! I think that the issue would be in the wires between ECU and injectors or something like that, hopefully.. And yes, i am spinning the CAS by hand. Sometimes i plug the CAS back for a crank with big magical hope if it would start but no..

[GTSBoy]

48 minutes ago, Raipe said:

So i can check the injector pulse also by hooking up an test light into battery positive and the other end to injectors wire one by one? If it grounds so the test light would blink fast as i understood. And the same thing from the ECUs pins to be sure that the ECU is pulsing them overall? 

No, not really. A noid light connects to the injector plug directly. Both power and pulsed earth should be present right there. You don't need to go to the battery. And an old fashioned globe type test light probably won't be fast enough.

If you get no flashes at the injector plugs, you can move your test backwards to the ECU's injector pins, but then you will need to provide power to the noid light and a test probe for the ECU from the other side of the light. This would just be to check the loom. You wouldn't expect to get a different result (from the injector end of the loom) unless the loom was torched somewhere in the middle.

[Raipe]

3 minutes ago, GTSBoy said:

No, not really. A noid light connects to the injector plug directly. Both power and pulsed earth should be present right there. You don't need to go to the battery. And an old fashioned globe type test light probably won't be fast enough.

If you get no flashes at the injector plugs, you can move your test backwards to the ECU's injector pins, but then you will need to provide power to the noid light and a test probe for the ECU from the other side of the light. This would just be to check the loom. You wouldn't expect to get a different result (from the injector end of the loom) unless the loom was torched somewhere in the middle.

Oh, yes now i got it!

[Raipe]

Today i tested with an other ecu from my friends R33 and injectors worked fine but car wont run cos it was stockecu. Mine has nistune on it. Is my ecu fryed or can it be something else?

[GTSBoy]

Sounds bad. Open the ECU up and look for burnt tracks or transistors connected to the injector pins.

[Raipe]

I did open the ecu. I didint find anything strange looking it by eye exept couple pins what are supposed to be so. I contacted our local tune shop ”zpower” and they said that it should be like that (Picture below) My ecu will be tested this week, so i will post the results of it! I am just curious what burnt my ecu if it is burnt, because i dont want to fry next 10x ecus.. it has nistune type 3 on it.

[GTSBoy]

What ECU is it? R32 or Z32 ECU are the correct choices for RB25 and they don't take a Type 3 board. They are Type 2.

[Raipe]

It is an J30 infiniti ecu. The elder R32 or Z32 ecus take Type 2 board yes correct, but they are 8bit so they are slow af. But the newer j30 ecu is 16bit. It has also better processor in it and they are much easier to find on sale. Older ones start to be under the stones..

[GTSBoy]

You're on your own then mate. You have ventured into foreign territory. If I had to guess, if there's no sign of burnt tracks from the injector pins, then you've likely killed the transistors that run the injectors. Odd to kill them all though....

[KiwiRS4T]

5 hours ago, Raipe said:

It is an J30 infiniti ecu. The elder R32 or Z32 ecus take Type 2 board yes correct, but they are 8bit so they are slow af. But the newer j30 ecu is 16bit. It has also better processor in it and they are much easier to find on sale. Older ones start to be under the stones..

Wow that sounds so far out! Have you had the car running with this set up at all? Has this been done before?

[Raipe]

15 minutes ago, KiwiRS4T said:

Wow that sounds so far out! Have you had the car running with this set up at all? Has this been done before?

Yup! Running solid soon for 4 years with 560whp and 690nm. Cp pistons, manley h-beams, acl bearings, all bolts ARP and cometic gasket. Head ported & polished. 840cc injectors with walbro 450 pump. This winter i am going to make some technical update, maxxecu. I may also open the engine and see what it has been eating for the last past years, just incase if something need to be changed..