Guys,

I've been tracing down some possible false knock as the car is pulling timing randomly and all accross the spectrum. The Knock sensor ohmed out in spec at 4K and the sensor wire is showing 4.2v? According to shoe box's site it should be showing 5v, is the 4.2v within spec? I did install a new sensor connector as the old was a little freyed at the clip. Let me know and thanks for your help.

 

Take the connector off the sensor. Then meausre from the single pin on the wire to the engine block. Should be 5.0V. If you only have 4.2V under those conditions, either the wire has some sort of resistance that is dropping the voltage, you have a bad ground to the block, or the PCM is not regulating its reference voltage correctly.

With the harness connector back on the knock sensor, the voltage should be between 1.5 - 3.5V. If you have a reading in that range, the circuit should still be capable of carrying the variable frequency signal produced by the piezo microphone in the sensor, and the PCM should not set a code for a faulty circuit.

 

Also make sure the battery in your voltmeter is good lol.

 

Thanks guys, I'll check again, but I think I have a bad volt meter or ground when measuring the voltage as the car is not throwing any DTC's for the KS circuit and if the problem lied with the wiring it should throw a DTC. I've got a new KS on order as I think my current one is bad giving me false knock randomly all over the place. I'll keep you updated.

 

KS resistance to ground with the wire off should be between 3300 and 4500 ohms. There needs to be as little thread sealer as possible where it screws in to get a good ground.

Over 4.1 volts (wire on) will set a DTC43.

Use another meter, they are cheap.

What rocker arms do you have?

 

4.2v is with the wire off the sensor. Also, I have the Crane Gold (SA) 1.6 rollers. I'm pretty sure the volt is fine as I'm getting no DTCs and the knock is very random and weird. Have a new KS on the way.

 

Can't use full RR with the standard KS. You need at least to switch to the LT4 version

 

That would be LT4 knock module.

 

Yes you are correct. I sit corrected.

Things have been very cloudy lately LOL

 

I already have the LT4 KM, installed it 4 years ago.

 

If the wire off voltage is 4.2 instead of 5. What will a new KS do? Apparently you don't believe the shop manual that says the voltage should be 5 and you believe that 4.2 is good enough.

 

Okay no need to be a smart ***, as you didn't even know the difference between a KS and a KM. Now:

Well, I think I have resolved my issue, and I'll findout for sure tomorrow when I can drive and log the car. I replaced my KS wiht a new AC Delco one and when taking the old one off I realized I really torqued the hell out of it when I installed it as I damn near needed a breaker bar to start unscrewing it and also I put a ton of thread sealer all over the threads. Two NONO's for a ks install I now know. So this time left the thread sealer off and torqued to the proper 14lbs. Keeping my fingers crossed.

Also, bought a new multimeter and now I'm reading the proper 5v in the circuit so I know it's not that.