Constant knock sensor reading…

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May 30, 2010 | 07:50 AM

Jerry D

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Joined: Aug 2009

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Constant knock sensor reading…

My problem is that I show 25.8 degs retard value from the knock sensor through the GMC 16168625, using TunerPro RT. This is a TBI install on a six cylinder 4.2 L Toyota engine with manual transmission. I’m using components from a ’93 GMC Safari Van that had the V6 with auto transmission. I have swapped ECMs with another 16168625 but had to use the same MEMCAL. I am using TurnerPro RT to trouble shoot and hopefully fine tune. I have a store bought ALDL cable with USB connector. I have checked continuity from the center of the wire that connects to the knock sensor to the plug at the ECM, and it’s at 0 ohms, so the wire into the ECM is good.

With either ECM I get the following:

With the knock sensor wire connected or unconnected at the knock sensor (and yes, I do have a bad knock sensor that has to be replaced) TunerPro RT shows 25.8 degs retard.

When I put a 3.9K ohm resistor from center of the knock sensor wire to ground, I still show 25.8 degs retard.

As for voltage, with using a 3.9 K ohm resistor from center of wire to ground, I get 2.4 Volts at the ECM plug, and still show 25.8 degs retard.

Could I have two bad ECM’s, or can the MEMCAL be the problem??? Is there any other way to test the ECM before I try to find another??? Is there a way to test the MEMCAL, I read about a knock sensor filter (?) but truly don’t understand what it is or where. Perhaps I don’t know how to set up TurnerPro correctly.

Any input, I can take criticism well, would be appreciated.

Thanks,
Jerry D.