Looking at mounting a knock sensor for tuning spark advance. Turns out early 4.0’s had them and mounted on the drivers side above the oil pan near the engine mount. Wondering what the thread size is as I’m trying to install this double ended bolt. This double ended bolt came from rockauto from a kit for a 97 ZJ. The thicker end doesn’t fit the hole on the block.
4.0 Knock sensor location thread size
JohnC7
Looking at mounting a knock sensor for tuning spark advance. Turns out early 4.0’s had them and mounted on the drivers side above the oil pan near the engine mount. Wondering what the thread size is as I’m trying to install this double ended bolt. This double ended bolt came from rockauto from a kit for a 97 ZJ. The thicker end doesn’t fit the hole on the block.
1 - 12 of 12 Posts
Looking at mounting a knock sensor for tuning spark advance. Turns out early 4.0’s had them and mounted on the drivers side above the oil pan near the engine mount. Wondering what the thread size is as I’m trying to install this double ended bolt. This double ended bolt came from rockauto from a kit for a 97 ZJ. The thicker end doesn’t fit the hole on the block.
As for the thread size, I have a tap-n-die set I use. If the tap fits, that's the size. Mine also includes a thread gauge that I use to identify if it's SAE 20 pitch, or metric 1.25 pitch. That clues me in to where to look for actual size. Knock sensors can vary in intensity of "microphone" output versus knock intensity; also there are the filters used where different knock sensors pick up different frequencies "louder" based on built-in filters.
7/16-20 fit but was a little loose but held on. The bolt that came with the knock sensor is m12 x 1.25 and here Engine mount hole mystery... - Jeep Cherokee Forum says the same thing that its an m12. I have an m12 x 1.25 tap on the way so I'll see if that will help/work
I plan on using this http://viatrack.ca/ which uses a knock sensor to a controller board which outputs to a 5 v signal. This kit is mostly used with megasquirt but im trying it with this PROLINK+ for MPVI2+ and MPVI3 – HP Tuners connected to MPVI3 OBDII Interface – HP Tuners
The prolink cable will accept 5 volt analog signals which i can use to log knocks on a chart. It wont retard timing for me but it will tell me what ranges I am knocking so I can adjust it.
IIRC the knock sensor went away due to issues with noise from the internals causing false readings.
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Got to imagine the lifters clackin away in my ol 94 ZJ would make it completely retarded...
Got a m12x 1.25 tap and threaded right into the hole perfectly. after tapping the double ended bolt fit perfectly. Off to installing all the knock sensor wiring!
I'll be curious to see what my results are. I know the sensor is tuned for engine displacement and the control board for the knock sensor has a sensitivity knob to also adjust.
1 - 12 of 12 Posts
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