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Rb25det Falling On Its Face, Just Swapped In 240sx.. Help Me Please?..

IslandBoy
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IslandBoy Explorer

IslandBoy

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Hey, recently put an RB25DET in my 91 240sx. Has multiple little problems, but the one I want to focus on now is some sort of power loss problem.

Has FMIC, Walbro 255LPH, Exhaust, Adjustable FPR, Intake

Since I got the motor put in the car it would pull fine Sometimes (1st gear and 2nd gear) ... now it just goes under full boost and makes no power, and hesistates. It also bucks some too. Ive checked boost leaks, and it has new o2 sensor and plugs... I'm really lost.. The problem gets worse the more I drive the car.

Its almost liek the vtc isnt enabling?

its a SERIES II btw.

Also what is factory base fuel pressure for this motor?

Any suggestions/help is much appreciated!

Adriano Grand Master

Adriano

Posted
Posted

Mate, i would check trouble codes, get rid of the FPR, try gapping the plugs down to .8 and stick it on the dyno. If you have get a consult, you can monitor the sensors, and for $60 they are invaluable for stock computer. How much boost is it running?

shnaped_second Mentor

shnaped_second

Posted
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and for $60 they are invaluable for stock computer

$60, from where? with software and usb cable? i could only find them in the US for over $100

IslandBoy Explorer

IslandBoy

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Well good news, checked error codes, retrieved code 34, which I assume is bad knock sensor. I reset the ecu then drove for 30secs and code returned, so It has to be bad.

My question now is, where is the knock sensor located on the SII Rb25DET Engine and what is a direct replacement/interchaneable part I can use?

Will a 300zx or KA24DE or Sr20DEt/DE work?

Thanks.

InterCooL Rising Star

InterCooL

Posted
Posted

not too sure if this helps, but the sr20det and rb series are fairly similar, and the knock sensor on the sr20det is located underneath the intake manifold, a lil plug that resembles a stethoscope, screws to the top of the block. would be a bitch to get to with the intake manifold in place :D

IslandBoy Explorer

IslandBoy

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not too sure if this helps, but the sr20det and rb series are fairly similar, and the knock sensor on the sr20det is located underneath the intake manifold, a lil plug that resembles a stethoscope, screws to the top of the block. would be a bitch to get to with the intake manifold in place :D

Yeah, i have an sr20 240 too.

I am aware now there are two knock sensors so it could be either one.. How can i check which one is bad? By testing the continuity?

Is there any way of disabling knock sensors"?

Adriano Grand Master

Adriano

Posted
Posted

There is a group buy on the forum for the consult, there is no way of disabling the knock sensor, if you disconnect it, it just gives the code, you could plug an oscilloscope onto the wire and see how much noise they are getting, should be able to test them, but i would check that they both have continuity in the wiring to them first, engine conversions can do funny things to wiring.

blind_elk Grand Master

blind_elk

Posted
Posted
Well good news, checked error codes, retrieved code 34, which I assume is bad knock sensor.
It's not indicating that you have knock, it's indicating a fault in the knock sensor circuits.

Have you checked that the CAS is working properly? Have you checked the base timing? Have you tried applying direct power to the VVT solenoid to see if it activates?

IslandBoy Explorer

IslandBoy

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It's not indicating that you have knock, it's indicating a fault in the knock sensor circuits.

Have you checked that the CAS is working properly? Have you checked the base timing? Have you tried applying direct power to the VVT solenoid to see if it activates?

Or the knock sensor could be bad as well. Where is the VVT solenoid at? I'm going to get a timing light later today and check the timing. What is a direct replacement for a knock sensor?

klh6686 Explorer

klh6686

Posted
Posted
Or the knock sensor could be bad as well. Where is the VVT solenoid at? I'm going to get a timing light later today and check the timing. What is a direct replacement for a knock sensor?

Are you sure both knock sensors are in tact and plugged in? i say this only because it is a swap into another chassis and it could be possible.

IslandBoy Explorer

IslandBoy

Posted
  • Author
Posted
Are you sure both knock sensors are in tact and plugged in? i say this only because it is a swap into another chassis and it could be possible.

Problem fixed, both knock sensors were not plugged in, the damn shop.

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