knock (detonation sensor) info

[cjparker1]

Who's changed one, how much probably way too expensive ...I'll hit up the junkyardWhere is it located on the engine, how hard is it to get to? thanks!The codes I pulled were 32 - egr and 34- detonation sensor.... I dont think the egr is going to matter much...am I wrong?
Modified by cjparker1 at 3:05 PM 1/18/2009

[pcproa]

Who's changed one, how much ?Where is it located on the engine, how hard is it to get to? thanks!

I bought a genuine Nissan Detonation sensor from ebay for about $65And I bought my subharness from Bernie over at twinturbo.net for but I believe about $25. I don't remember the exact price.

It is located underneath the lower plenum mounted to the engine block between the cylinder heads. It is extremely hard to get to it. The first and most common method is to pull off the upper and lower plenums to get to it. That includes pulling the timing belt and everything.

The second method and is not as easy IMO, you have to pull off the transmission and flywheel, then put a wrench in the small cavity and un-wrench the old sensor.

You can relocate the detonation sensor, but I wouldn't regularly recommend it.

[cjparker1]

when you take off the timing belt, do you have to do something else to reinstall or just put it back on? Also, if I'm throwing that code...does it mean I need to replace the sensor...or can it be from faulty fuel spark, detonation...etc..???

[HellHamer]

ok i know what detenonation is too much air + not enough fuel = running lean/ big boom!

so what does a detonation sensor do?? sry i dont mean to pull away from the main topic

[pcproa]

when you take off the timing belt, do you have to do something else to reinstall or just put it back on?

After you take off the timing belt, you pull off the front plates behind the Camshaft Pulleys. Then you'll be able to take off the lower plenum. Re-assembly is the reverse of dis assembly.

I'm not sure exactly what you mean, but you need to compress the Timing Belt tensioner and line up the marks to put the belt back on.

Also, if I'm throwing that code...does it mean I need to replace the sensor...or can it be from faulty fuel spark, detonation...etc..???

This is a basic question for Automotive diagnosis and repair. The first thing I learnt when learning about ECU diagnostics is, that a faulty thrown code could mean that something else is wrong before hand but hasn't thrown a code yet.For example: A faulty O2 sensor showing lean with a trouble code could mean that the MAF sensor is bad because it's falsely sensing a shortage of air and the ECU is shortening Pulse Width of the injectors to compensate. So even though the MAF sensor is faulty, the O2 sensor sees an error.

In our (pre) OBD1 8-Bit ECU's, all error codes thrown are assuming the sensor is faulty other than the O2 sensors. It may or may not actually be faulty, but if you change a sensor to a good sensor and the problem is still there, then that means the problem is further upstream.

ok i know what detenonation is too much air + not enough fuel = running lean/ big boom!

so what does a detonation sensor do?? sry i dont mean to pull away from the main topic

A detonation sensor is nothing more than a microphone that listens for supersonic or ultrasonic sounds and reports it back to the ECU in the form of Resistance. When a detonation occurs, a supersonic sound is heard by this sensor through the metal that it's mounted to. Similar to you putting a cup to a wooden wall and listening to someones conversation in the other room.

Cars, especially turbo cars, experience regular mild detonation all the time, and the job of the detonation sensor is to record the extreme sounds of detonations or the big detonations.

To the OP.If you are getting a Detonation sensor or Detonation Sensor subcircuit faulty code through your ECU (code 34), that does not mean your car is detonating.What's happening is your car is recording a constant, non changing detonation, which is impossible. The ECU knows it is impossible so it throws it into failsafe mode as a result.

[HellHamer]

ok ty man.....

[cjparker1]

Ok that made sense to me ...but I'm going to switch 2 coilpacks and a few plugs on them because from what I'm testing, I'm showing that at least of the cylinders are not even firing lol...and the clips look busted...

Do I turn the ecu screw again to delete the codes?? I need to delete it to retest once I've changed parts...

Also...How the hell do you get the rear two spark plugs out?? I'm new to my z but it appears to be a coolant (metal) line over the rear two coils?? I remove that? so I have to drain the radiator??? Someone clarify please lol...

And, I know I'm full of questions...but my engine check light isnt on when I start and drive the car...but It throws codes when I turn the ecu screw??? I also rev to 7500...Is that because this is a new engine from japan??? Im throwing a 32 code which is egr...is that because it's from japan also??

any ideas appreciated, thanks guys!

[pcproa]

Do I turn the ecu screw again to delete the codes??

Yes. They delete again when you leave the diagnostic mode. To leave the diagnostic mode you need to turn the potentiometer again, fully clockwise and then fully counter clockwise back to the original position.

Also...How the hell do you get the rear two spark plugs out?? I'm new to my z but it appears to be a coolant (metal) line over the rear two coils?? I remove that? so I have to drain the radiator??? Someone clarify please lol...

It is an air passage connecting the left intake bank to the right intake bank effectively equalizing intake pulses. It is not for coolant. You need to take it off. Both sides have little rubber seals between the surfaces.

And, I know I'm full of questions...but my engine check light isnt on when I start and drive the car...but It throws codes when I turn the ecu screw???

It's supposed to. It will flash the codes for you

I also rev to 7500...Is that because this is a new engine from japan???

I don't know what you mean about revving it to 7500. If you are testing O2 you rev it to 2000RPM. Please clarify.

Im throwing a 32 code which is egr...is that because it's from japan also??

It has nothing to do with it being from Japan. The engines are the exact same minus the fact that on Turbo Engines, USDM cars use precats for dump pipes from the turbos where JDM uses a straight through design. Everything else is exactly the same when it comes to the engine.

EGR is at the back of your engine if you've left it on there when you changed the engine. The solenoids for the ECU to activate it are at the right side of the engine bay behind the strut tower.

[cjparker1]

Ahh k , thank you sir lol...

So my engine check light, despite having codes, will stay off while the car is on and driving?? that's so strange...

and I meant literally my car revs to 7500 rpm before the limiter hits...From what I've read the others rev to 6700...or am I mistaken? or is that just automatics?

Thanks again pcproa

[pcproa]

So my engine check light, despite having codes, will stay off while the car is on and driving?? that's so strange...

My Z, and every other Z that I've tinkered with has. I've never seen it come on while running in normal ECU mode.

and I meant literally my car revs to 7500 rpm before the limiter hits...From what I've read the others rev to 6700...or am I mistaken? or is that just automatics?

My stock limiter was 7000. Stock for AT is also 7000It is possible to go above this limit though. Say for example, you were driving at 6G in 4th, and you downshifted to 3rd, you would probably go well past 7G. Please don't do that though.

Otherwise, maybe you have an aftermarket ECU. Have you checked?

[cjparker1]

ok good...and yea I dont downshift into it lol...but i just rev it outta gear it goes well past 7...my ecu looks stock, I dont know how to tell lol

[valkyie]

I have a question about the knock sensor. If the ECU puts the car into failsafe mode would that shut a Z32 Na off? I have been having this problem for a long time. My Z will run for around twenty minutes and then just shut off. No stutter, hesitation, just shuts off like you turned the ignition off. The car will not start for a few hours. Then a few hours later starts up fine. Then either that day or a few days later it does the same thing again. I am at a lost.

[maximilianaire]

If the ECU puts the car into failsafe mode would that shut a Z32 Na off? I have been having this problem for a long time.

Wow this is ancient.
I have some input, and if anyone is reading, have a question to follow.
My NA just experienced a code 34 a few days ago. I have done a lot of reading, and it's in "safe mode" to protect the engine. The car will run, with added fuel and retarded timing, but something else is causing valkyie's car to shut off. Mine just runs like crap, smells like fuel and my timing is on the short bus.
Question is where can I find either a thread on removal of the lower intake mani, or a diagram. I've seen what a PITA it is to remove the upper plenum and can manage that, but not sure on the rest, including removal of the timing belt and cam gears... why do the gears have to come off???
I know that I will be replacing my timing belt if it comes off, just don't trust the prev. owner at all... I want to get the 120k done asap, I'm at 122k and holding until code 34 is resolved and I can exit safe mode.. I know water pump, timing tensioner, cam seals, and timing pulley's, is there anything else that needs to be addressed?
Lastly, the sub-harness. It's recommended to replace it because of low voltage to the connector, and sensor, right? Also, I think my clip is about to break anyway, 21 years young and exposed to the heat of the z32's engine bay... I'm learning, lol. Well, My question comes from my being "wiring challenged", Input on properly replacing connectors on the z32 harness and things I should avoid.

Thanks in advance,
Max

[t.mcginley.jr]

The uppper intake is harder to take off than the lower intake. It sits on 4 studs which have nuts + 6 bolts. The center idler bearing for the timing belt bolts to a stude that sticks out the front of the lower intake. Even if you take the idler off, the stud will not let you lift the lower intake off of its studs because the rear timing covers are in the way. So in order to take the rear timing belt covers off, you need to take the cam gears off. So after you get the cam gears off and rear t-belt covers off, just unbolt the lower intake and lift it straight up.

This is precisly the reason why people opt to relocate their KS to the back of the plenum. Here's the TT.net tech article about it:

http://twinturbo.net/nissan/300zx/forum ... ation.html

I plan on doing the relocation to the 3rd location on mine. It still works as it should and makes replacing it wayyyyyy easier. You might as well replace the harness for it while you're there. Most of the connectors throughout the engine bay will break. As for replacing them, you cut the old one off and then solder/heat shrink the new one in. There are YouTube guides on how to do automotive soldering.