Where to buy? Knock sensor for 90' RENIX

[xjtrailrider]

I need one! Anybody know where to find a knock sensor for a 90'. I've searched the net and no luck! The dealer wants $90 and AA/AZ wants $75. I'm not spending that much and at this point I'll take a good used one.

Mine is broken in half so it wont function at all!

[5-90]

RENIX has sufficiently low compression that spark knock isn't that much of a problem - you can run without it for a while.

I don't know about the OEMR, but the aftermarket replacement (GPSorenson and, I think Borg-Warner) will come with a stud that threads into the hole, the sensor (which goes on the stud,) and a nut to retain the sensor. This doesn't matter - the critical point is a solid mechanical attachement to the engine block. The "ring thing" is just the aftermarket's way of reducing part numbers - all Knock sensors are, basically, piezoelectric sensors, and that way they just need to change the stud for different applications...

5-90

[xjtrailrider]

So if the connection is left "open" it won't affect the function of the CPU or ignition? If it won't, then I should be O.K. for now!

[muddshutter]

The sensor is not really needed unless your engine is old and tired. It will not effect anything if its not there.

[muddshutter]

If one day you decide you need it, its $60 for an OEM one and i can get it for you in a week.

[Saudade]

I've been running without one in my '88 for nearly a year. It merely retards the timing if it starts to "hear" any knocking (detonation). Just keep using decent quality gas and keep you ears open.

[xjtrailrider]

Thanks for all the replys.

I decided to go ahead and buy a new one, found local for $70.

Thanks for the offer of help muddshutter!

5-90, as always your advice and expertise is golden.

Since I'm doing a restoration on this XJ and the "newly rebuilt" original engine is going in next weekend, I just decided to spend the money for a new sensor and be done with it since everything else is practically new!

[lawsoncl]

Back when I was doing engine work for a small race car in college, I found you can trick the computer into thinking it's detecting knock by putting a 1500 Hz Square wave (I think that was what I used) into the knock sensor wiring. It was our method having a seperate traction control computer tell the ecm to pull back on the power. The traction control computer never worked right as the EE weenies never could figure that out which was also the reason I never let them do anything but provide a fake knock sensor signal. We also used this trick to pull back the engine power when we hit the button for the air shifter which just blind shifted without clutching. Also discovered that pulling the timing back to zero was a great way to spin up the turbo charger while sitting still at the starting gate. Also turned the exhaust cherry red if you did it too long.