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Knock Sensor Connector, Renix 1990 I6 Motor

Black1990jeep

NAXJA Forum User
Location
california
On my 1990 Remix six cylinder XJ the wire harness connector that plugs into the knock sensor is broken. This is a two prong plug. Looks simular to the fuel injector wire harness connector I think, hard to tell cause there isn't much plastic left!

This is the knock sensor located on left side of engine block, down low just above oil pan midway between front and rear of the block.

What is the name of this kind of connector?, Or maybe a part number, or better still a vendor contact who can sell me a replacement?

Getting her ready for smog, just put in a new O2 sender, old one was filthy inside, rust colored on one side. I have a new catalyst to go in next, old one melted down and clogged 500 miles from home, so it got cleared out to get home!

Anyway if anyone has a line where to get that knock sensor connector that is on the harness, I sure will appreciate your help.


Also a technical question about the ecu...

If knock sensor signal to the ecu is lost, will the ecu lock down the timing advance to a low safe value, (limp home mode) or will the ecu think, "hey I detect no knocking", and then run up the advance to upper limit?

Thanks!
 
It's bosch connector.
You can find same connectors on many cars, for example on BMW engines (fuel injectors)


https://www.efihardware.com/products/2035/Injector-Plug-Compact-Bosch-Type







Also a technical question about the ecu...

If knock sensor signal to the ecu is lost, will the ecu lock down the timing advance to a low safe value, (limp home mode) or will the ecu think, "hey I detect no knocking", and then run up the advance to upper limit?


That'g a good question. I would also like to know.
 
As for the knock sensor, it would be option #2. When a knock is detected the sensor generates voltage to send to the ECU. When the voltage get high enough (don't know how high), the ECU retards the timing. No voltage (or low voltage) = No knock.

Mine hasn't worked for years. Just use good quality gas. One day I'll replace it.
 
On my 1990 Remix six cylinder XJ the wire harness connector that plugs into the knock sensor is broken. This is a two prong plug. Looks simular to the fuel injector wire harness connector I think, hard to tell cause there isn't much plastic left!

This is the knock sensor located on left side of engine block, down low just above oil pan midway between front and rear of the block.

What is the name of this kind of connector?, Or maybe a part number, or better still a vendor contact who can sell me a replacement?

Getting her ready for smog, just put in a new O2 sender, old one was filthy inside, rust colored on one side. I have a new catalyst to go in next, old one melted down and clogged 500 miles from home, so it got cleared out to get home!

Anyway if anyone has a line where to get that knock sensor connector that is on the harness, I sure will appreciate your help.


Also a technical question about the ecu...

If knock sensor signal to the ecu is lost, will the ecu lock down the timing advance to a low safe value, (limp home mode) or will the ecu think, "hey I detect no knocking", and then run up the advance to upper limit?

Thanks!
The connector is the same as an injector connector. The wire to the sensor is the only shielded wire in the system. The sensor is simply a piezo high Z microphone tuned to the frequency of a ping/knock. If the sensor is not connected, the cable is not terminated and will act as an antenna and can pick up ignition and all sorts of noise, fooling the ECU into thinking the engine is knocking. This will cause the timing to be retarded and can significantly reduce performance. If you are not going to use the sensor, put a 100 ohm resistor across the contacts to load the cable and cut the spurious noise.
 
i was asking same question in separate thread never got a response if sensor is unplugged the ecu runs full retarded is my understanding is this true as im having detonation issues climbing hills unless i down shift enough the rpms go way up currentl mine is disconnected and am trying to find out if i should hook back up to help with the detontion on grades
 
Thank you all for the info. That rf noise fooling the sensor never occurred to me. anyway my goal is to hook it all back up with a good new connector. I will test the existing sensor. I understand if it is working, it will produce a voltage if rapped on. measurable with a digital meter set to read AC Volts.

if bad, then I will get a new one.

thanks again!
 
Thank you all for the info. That rf noise fooling the sensor never occurred to me. anyway my goal is to hook it all back up with a good new connector. I will test the existing sensor. I understand if it is working, it will produce a voltage if rapped on. measurable with a digital meter set to read AC Volts.

if bad, then I will get a new one.

thanks again!


Don't bang on it too hard as that can break the piezo crystal. I'd just stick the voltmeter on there while the engine is running and see if you see anything.

I helped on a traction control project way back in college. The EE's had been trying to reverse engineer the ECU for 3 weeks, trying to figure out how to reduce power when they detected wheel slip. I cheated and simply fed a 1-kHz square wave to the knock sensor, which tricked it into pulling the timing back to the minimum (which they could configure as low as zero). They never did get their wheel slip detection to work. But we installed a button to trigger the knock sensor while sitting at the starting line. Pulling the timing back to zero turned out to be a great way to get the turbo spun up right before launch. :}
 
I would be worried about carbon buildup. I would run a can of BG44K through the fuel to clean everything. I run a can every 10K miles through every car I own. I routinely put 400k on a vehicle before I get rid of them.
 
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