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more knock sensor questions........

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Old 03-25-2002, 09:37 PM   #1
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more knock sensor questions........

if my knock sensor isn't connected due to wiring problems... what exaclty will happen? does the knock sensor only listen for knocks and tell the comp that it hears it?

does the knock sensor HAVE to be connected for the timming to stay at what it was set at. or will it be retarted since its not connected? also, what happens if the wire is grounded out and there is zero resistance?
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Old 03-26-2002, 02:19 AM   #2
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Every time you start the car the ECM tests the knock sensor and expects a certain response. If there is no responce (Knock sensor disconnected) you will not be able to get a full spark advance and you might even get SES light.

When i had my KS disconnected a while back when i hit the gas hard i would hear my car detonate. I connected it right after that run and no more detonation.

IMO i would hook it up if you can and if you can not for a reason do not drive hard for that time. The KS protects your engine.
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Old 03-26-2002, 09:01 AM   #3
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You will definitely get a Check Engine light. If the ECM doesn't see something with 3900 Ohms of resistance to ground out on the end of that wire it WILL throw the penalty flag. Your ECM will go into "limp home" mode and generally run like crud.

If you would like to temporarily bypass it to do some testing (I think I know what you're after here) then simply run the KS wire to a $.012 Radio Shack 3900 Ohm resistor and then on to a good ground. This will trick the ECM into thinking it's still there but, obviously, it will never register and knock.

Please note, it will take about 1/2 hour of driving around under various throttle conditions for the ECM to unlearn any knock it had learned from before, unless you reset the computer. It remembers where it heard knock just like it remembers fuel curve information.
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Old 03-26-2002, 11:56 AM   #4
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On your '88 you will not get a code for having the knock sensor disconnected. On a 90-92 car you will get a code. I ran my 85 and 89 with the knock sensor just disconnected with no problems. I now run the resistor like previously stated, with no problems. I always run 93 octane, I like this setup. I get full advance and no retard.

The engine can knock without you hearing it, so if you take this route always run good gas.

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Old 03-26-2002, 02:55 PM   #5
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ya, im running 93 octane, so hopefuly im good until I get it fixed.
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Old 03-26-2002, 05:28 PM   #6
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ok, so im running about 16* BTDC timming. and about 6* BTDC with the connector thingy disconnected. (forgot the name of it, the one near the A\C box in the engine compartment)...

and this is with the knock sensor not connected. does it sound right? i mean will the computer retard the timming any if the knock sensor isn't hooked up?
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