jklopez09

about to do a cam swap in a few weeks and was wondering if my car has a knock module? if so should i change it to prevent false knock?

jklopez09

not sure if it matters but the engine is out of a caprice. im using the z28 computer and wiring harness

n2ceptor

Yes, its located on the passenger side....

shoebox

No, a 93 f-body ECM does not have a replaceable knock module. All knock circuitry is wired into the ECM.

Injuneer

That would be the knock sensor, not the knock module.

What the engine came out of does not matter. You have to use the correct knock sensor (4Kohm) in the block, to match the 93 ECM. The 93 ECM does not have a knock module.

jklopez09

so do i need to change it out or will it be fine like it is?

Injuneer

You don't even know what engine you have.... but you expect me to give you a definite answer on changing out the knock sensor? Not a very reasonable request.

Measure the resistance of the knock sensor on the new engine. If it has a resistance (measured from the single pin on the sensor to the block) of about 4,000 ohms, you have the correct sensor. If it has a resistance of about 100,000 ohms, you will have to use the sensor from your 93 engine.

jklopez09

i am using all the sensors from the 93. my question is do i need a different one for the cam swap? is my swap going to cause false knock?

Injuneer

The most common cause of false knock is the noise from full roller rockers. That's what the LT4 knock module was designed to eliminate. Since your 93 can't use the LT4KM, there's not much you can do. There is only one knock sensor that will work with your 93 ECM, and that's the 4,000 ohm sensor that was used 93-95. You can't change the knock sensor to filter out the sources of noise that cause false knock. You can have the ECM's response to the knock sensor made less sensitive in the tune, or you can use an external circuit involing a resistor to "desensitize" the knock sensor. But you have to understand that either of those actions will reduce the knock sensor's response to true knock as well.

jklopez09

Which would you do? im going with 1.6 full rollers. how will i be able to tell if i get false knock?

Injuneer

Put the correct knock sensor in. Get the engine running. Put a scanner or data logger on it and see if you are getting any knock retard at all. If you don't have knock retard, leave everything as it, for maximum protection from the knock sensor. If you do have knock retard, then you have to sort out whether its in response to "real" or "false" knock. Generally, you can try running high octane fuel, pulling timing, richening the mixture, etc. If none of those eliminates the knock retard it probably is false knock. You don't have to decide what to do with the knock sensor until you prove its false knock.

I would keep the maximum capability of the knock sensor system to protect your engine from detonation. One tank of bad fuel, and you can detonate and do damage, without the knock sensor protection.

For the record, I can't run a knock sensor with my solid roller camshaft, so my insurance against bad fuel it running spec fuel out of a drum, particularly when spraying a 300-shot. But then you can't get 117 octane leaded fuel out of a pump, anyway.