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knock sensor bypass

A

Anonymous

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is there any way to bypass the knock sensor on a 87 740 turbo.
will disconnecting it bypass it or would it make the ecu suspect knocking
 
I have heard that it assumes knocking if you disconnect it, I have an old style sensor that i removed from the block to install a new style for a seperate knock detection system.

I say unplug it and see, just listen for detonation. If you lose a ton of power, remove it form the block and leave it connected. If it STILL retards timing, ground the sensor to the block with a wire, that should for sure fool the computer into thinking its connected.
 
it doesn't like the knock sensor being disconnected (when we tried it, the car wouldn't go over 45mph or something like that, it'd cut off...)

Why would you want to disable the knock sensor? esp on a car of that vintage? the bottom end (esp the pistons) dont take too kindly to detonation...
 
Then disconnect it and ground it. the ecu will not know the difference if the sensor is recieving its ground because it is in the block, or because it's grounded by a wire. It's identical electrically.

Disconnecting the knock sensor is a VERY common mod on cars such as the Ford 2.3 turbo. Reason being they're way oversensitive and retard timing un necessarily. I would never run a car with one connected, then again I monitor things pretty carefully...
 
You might try a copper spacer/washer to effectively 'dampen' the sounds of knock (or in your case, slap). I've seen ones offered on sites for VWs and such that have overly-agressive ignition retard. HTH...
 
Out of curiosity, how exactly does the knock sensor work? Like is it just a piezo pickup or what?

I feel silly asking it but it's one of those simple stupid things i've never really thought about too hard
 
Yes, it's pretty much a tuned piezo-like sensor. Depending on your level of engine management, the system is either a simple 'always-on' kind of thing, or it is rapidly switched on-off so as to pick up vibration only during the period of time that knock can occur, thereby isolating not only the knock itself, but which cylinder caused it.
 
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