Hi there. Due to a lack of options, i've had to use an AJ6 bottom end transplanted into a X300. The head and all other ancillaries are from my AJ16 and they fit just fine.

Except the knock sensors.

The old block does not have knock sensor mounts, so I need some advice here.

Question 1: What is the thread specification of the knock sensor?

Question 2: There are some unused blank lugs on the left and right of the water hose. I'm wondering if i can use an epoxy or weld a nut there to attach the knock sensor.

Question 3: Let's say I do without the knock sensor altogether, how would the ECU respond?

Question 4: Are you still able to source this knock sensor?

Thanks!!

 

I'm confused or just dumb. The XJ6 and the X300 are the same car, right? Well what is an AJ6. I know the AJI6 is the engine in the X300, I think. A little help with the designations please.

 

AJ6 is the predecessor to the AJ16 engine. Wikipedia covers it well enough if you're interested.

 

Hi Kopi,

The documents at the links below may be helpful in understanding what the ECM expects from the knock sensors:

http://www.jagrepair.com/images/Auto...300%201995.pdf

ftp://ftp.ndm.net/Chuck/J-CD1/data/j...1k0716rpdf.pdf

http://jagrepair.com/images/Training...20-%202000.pdf


Cheers,

Don

 

Thanks for the links Don. I've gone through those before but did not find the answers that I was looking for.

EZDriver, Vee is right. The AJ6 and AJ16 shared the same bottom end. The block is almost identical, well, except for the knock sensor mounting points that are absent on the AJ6.

Hence, my options are really limited to
- disconnecting the knock sensors altogether, but i'm unsure how the engine would respond
OR
- somehow weld or use an epoxy to attach the knock sensors to the block.

Anyone?

(realized that my post in other sections, example: engine section, has been deleted. Is it against forum rules? I was hoping to get the attention of other folks that may not be looking into the x300 threads specifically, since my engine does cross models)

 

Kopi,

I'm traveling, but back home I have a printed version of an AJ16 Engine Management Dealer Training manual that is different from the ones in the links I posted. It's possible that it may contain some additional info about knock sensor behavior and ECM expectations. I'll try to remember to check when I'm back (probably Monday).

As I recall, the knock sensors are piezo type transducers and either the sensors or the ECM software is tuned to sense noises within a certain frequency range (I seem to recall that this range fell within the human hearing range). I don't recall whether the ECM requires a certain base level of noise to consider all is well.

It is possible that as long as you connected the sensors to the wiring harness for the resistance/inductance the ECM expects, you might be able to simply position the sensors anywhere they would receive little vibration that could cause false interpretations by the ECM and lead to unnecessary timing retardation and increased fuel injector pulse durations to cool cylinders that are not actually hot because there is no pre-ignition or detonation.

Cheers,

Don

 

Thank you Don that was helpful. I'm starting to understanding a little more about knock sensors. Seems like it requires a base reading to provide a reference frequency over a set period of time. It then uses that reference frequency to detect knocks that generate "out-of-range" frequencies.

So, it needs to be connected somewhere. I'm thinking these points (circled in color).

Probably going to weld or JB weld a nut there and screw the knock sensor on. The one on the right should be ok. I'm concerned about the left as its directly in the path of the water hose I believe, and I'm not sure if I can re-route it.

If anyone else has a better idea, please let me know.

Thanks!!