Knock Sensor

[Kaiju Senso]

Engine is a LNJ 3400 from a 2005 Equinox and I'm wiring it to run off of a 98 monte carlo harness and PCM (3100). The Equinox has 2 knock sensors bolted to the block on each side but the previous 3x00 have just one sensor that screws in above the starter. The holes are not the same size so I can't just screw the 3100 knock sensor into the LNJ motor. So there are two ways to go around this that I was thinking, which would be the best?

Drill and tap one of the old knock sensor holes for the larger 3100 sensor and just plug it into the harness, or

rewire the monte harness to accept one (or two) of my LNJ knock sensors. The 3100 sensor is 1 wire while the two on the LNJ are two wire. Will wiring both knock sensors be of any benefit.

[CNCguy]

We use the coolant drain plug hole on the rear of the engine near the CPS. Be sure the threads are clean in the block and use thread sealer. The KS needs to be grounded through the threads or it will not work.

[Kaiju Senso]

Ah I didn't realize the Knock Sensor would work correctly anywhere else. Does this look correct?

[boomofdoom88]

I do beleive it should be on the front by the oil filter. la1 and lx9 both have the whole for it there. Maybe the lnj doesn't however?

[Kaiju Senso]

Well if anyone could explain how these knock sensor work that would be helpful. Here is a picture of the starter side of the motor. Both sides of this motor have a knock sensor, but the coolant drain plug on this side is too close to the oil filter section of the block for this style sensor to fit.

[pocket-rocket]

The bolt holding the new style knock sensor to the block isn't the same thread size/pitch as the old style knock sensor?

[boomofdoom88]

Well if anyone could explain how these knock sensor work that would be helpful. Here is a picture of the starter side of the motor. Both sides of this motor have a knock sensor, but the coolant drain plug on this side is too close to the oil filter section of the block for this style sensor to fit.

The 2 knock sensors in the block now come out. They wont be used. The knock sensor you need should thread right into the front hole where the other one came out of. IIRC its not a through hole just a boss. I just re-read your op and you state the threads dont match, I would just tap it to the larger size if it was me.

[CNCguy]

The KS is basically a microphone that listens for knock and will work on the front or rear of the engine. The sound (vibration) carries through the block.

Where you have the KS will work fine but if you want to put it in the front and have access to a drill and 1/4" NPT tap it is not very hard to put threads in the old boss. Retapping the holes don't work for our application due to header clearance.


Jon, the older KS have a 1/4" NPT thread while the newer ones have a through hole and use a M8 bolt to mount it to the block.

[Kaiju Senso]

Thanks for the replies and thanks CNCguy for explaining the knock sensor differences with specifics. This motor is going in my Fiero so the location right now will make it easier to remove and drill and tap the knock sensor on the same side of the block (if it doesn't work for some reason)

[pocket-rocket]

Jon, the older KS have a 1/4" NPT thread while the newer ones have a through hole and use a M8 bolt to mount it to the block.

Ah, ok. I didn' know the specifics, but figured it was worth a shot in hopes of finding a super simple solution.