Rb25 Problems

[DVS JEZ]

Did u use 500kohm resistors? How did u wire them in?

[95_240]

I used 1M ohm resistors. I wired one side of the resistor to the harness and the other to a ground.

[DVS JEZ]

Swap it out for 500kohm

[95_240]

I realized after I tested it that I used 1M ohm that was meant for the z32 ecu and then saw in the write up on here that it was supposed to be 500k ohm. My next question is even with the 1M ohm it idled fine at lower temperatures. It didn't start running rich until it was warmed up. Do the knock maps not activate until the engine has reached a certain temperature?

[DVS JEZ]

Nissan ecu's do weird things to play with our heads.

[Mitcho_7]

Nissan ecu's do weird things to play with our heads.

Agreed on that!!!

http://www.trademe.c...n-465141160.htm

That's a ridiculously good price for an rb25det power fc, almost wanna buy it!

Edited April 11, 2012 by Mitcho_7

[89CAL]

Yeah I was saying that the ECU's are sensetive and little changes can make them go crazy. And I was also getting at the fact that putting resistors in place of the knock sensors may be causing problems. Either plug them directly into the knock sensors or run nothing at all, but your computer will always see knock = 0

[DVS JEZ]

Yeah I was saying that the ECU's are sensetive and little changes can make them go crazy. And I was also getting at the fact that putting resistors in place of the knock sensors may be causing problems. Either plug them directly into the knock sensors or run nothing at all, but your computer will always see knock = 0

Doesnt exactly work that way

Unplugged will have extremely high resistance as its open loop circuit.

Plugged in if the knock sensor is faulty will give an abnormal reading also.

The ecu needs to see ~517kohm resistance otherwise it will think there is knock or a faulty sensor and trigger a safe mode or

Knock map

[89CAL]

Doesnt exactly work that way

Unplugged will have extremely high resistance as its open loop circuit.

Plugged in if the knock sensor is faulty will give an abnormal reading also.

The ecu needs to see ~517kohm resistance otherwise it will think there is knock or a faulty sensor and trigger a safe mode or

Knock map

Oh I thought they always went off frequency and putting a resistor in wouldnt work.....

Well I take it back then lol

[DVS JEZ]

They read Frequency but convert it and output to something the ecu can read afaik

[89CAL]

They read Frequency but convert it and output to something the ecu can read afaik

ahh I'm an idiot lol, whoops

[GTSBoy]

Actually, they are just piezo microphones essentially, and send a frequency signal to the ECU. The ECU has a whole section (was a whole daughterboard on the Type 2 ECUs like R32) for decoding the signal received and deciding if it is knock or not.

[95_240]

I did check the resistance on the knock sensors and they were around 500K without the car running. I have no idea what they are reading when it is running. Hopefully my Nistune board will come in the next few days and I can confirm that it is going into the limp home map.

[95_240]

Do the limp home maps make the car run so bad that it cuts out at low rpms? When driving around parking lots it will cut out and jerk pretty bad.

[DVS JEZ]

Actually, they are just piezo microphones essentially, and send a frequency signal to the ECU. The ECU has a whole section (was a whole daughterboard on the Type 2 ECUs like R32) for decoding the signal received and deciding if it is knock or not.

Ok thanks. Yes the type 2 boards have a knock board. Are u 100% sure that they out put a frequency on all the nissan knock sensors? I have not researched this

[GTSBoy]

Well, there's no smarts in the knock sensors.....they're just a piezo element.

[89CAL]

either way if he is getting a nistune it should help the problem.

To OP, what sort of fuel is available over there? perhaps that has something to do with it as well? I'm not 100% sure, but I think the Nth American fuel is not overly fantastic. Perhaps the combination of the mods and a poor octane rated fuel is causing the problems.

Just a thought anyway. Nistune should be a goer

[GTSBoy]

Nah, you can get fuel that is easily as good as our 95RON, and 98 equivalent is around as well. It's just that they use a different octane number in the US that has lower numerical values for the same quality.

[89CAL]

I just remembered hearing something about American fuel not being as good. but if that's the case then scrap that idea

Maybe it wasn't as good as Jap fuel, but that's no different to here anyway

[95_240]

I'm using close to the equivalent of 98 RON. I got my Nistune license today and the board was shipped out so hopefully I get it by the weekend. I also found a thread by wlspn and he was producing the same injector times that I was at idle. I sent him a pm and his setup was almost the same as mine but he was using a larger turbo. I'm pretty confident that it is going into limp mode and maybe the Nistune can identify the problem so I can fix it or change the tune if need be.

Edited April 12, 2012 by 95_240