If a knock sensor goes bad ................

[carter200]

Will or can there be an audible knocking sound (like a bad rod bearing) that can be easily heard? Just curious, thanks

[rhipsher]

Do you hear a knocking sound?

[carter200]

Do you hear a knocking sound?

Yep and it's a loud one :confused:

[rhipsher]

Yep and it's a loud one :confused: Oh sheet! Might be a bad lifter but if i's really loud then maybe a rod bearing P.Med you.

[Kb7tif]

On my 92 a complete main bearing set was installed (motor was pulled) Still had a knock not a tap a deep lower knock. Crank or connecting rod culprit.

[Aurora40]

Just a peanut gallery two cents. But I believe the knock sensor is tuned somewhat specifically (via a crystal with a certain resonant frequency? Or at least that's what I thought) to the tune of a ringing block. I don't know if clunky noises will necessarily affect it.

I do believe though that the ECM will advance the timing to a point where it expects knock, as a self-test of the sensor. If it didn't see a knock signal, it will set code 43. It won't run the test if it sees knock signals before it gets around to running the test.

So if your knock sensor is MIA, it should throw a code.

Also, there's practically no way you should have knock at idle or low throttle. The cylinder pressures are really low. So if you hear it all the time, I wouldn't think it is spark knock.

[carter200]

Thanks for the thoughts guys. Anything else that might cause a knocking sound besides rods and crank in an LT5?

[A26B]

Dual mass flywheel commonly sounds like a rod knock at idle when it gets "worn". if you advance the rpm to 1,000~1250, hold it steady & the knock goes away, it's probably the flywheel.

If the knock is not present at the higher rpm, you may have a weak miss. You might consider new plugs or gapping closer at about ).040"~0.042". Demps favors the closer gap on the later cars, I'm on the rail whether that's a good move.

The real problem is probably the Dunn heads. I have a real nice pair of 90 Birmal heads that I would trade with you, being the good ol boy I am! You know how we Okies take care of our neighbors to the south.

[carter200]

Jerry,
I bet you do have a set of Birmals for the far superior DUNNs but the knock problem is NOT my car. My 95 purrs like a kitten ;) I have received news on the possible cause of the knock and will let the owner speak after checking it out.
Good to know my friends to the North are so thoughtful :worship:

[Z51JEFF]

A dead cylinder will cause the knock from the flywheel.I got this with dead injectors,dead coil.Carter,hows my TB plate coming along?

[carter200]

A dead cylinder will cause the knock from the flywheel.I got this with dead injectors,dead coil.Carter,hows my TB plate coming along?

Jeff,
You have a PM ;)

[Jim Nolan]

It is my understanding the Dunn heads flow better than the Birmal heads. If that is the case than my ported Birmal heads and recut valves are, performance wise, better than the Dunn heads. So if this be true all stock Dunn heads give you is strutting power. If I'm wrong then chime in.

Sorry if I stole this thread.

[DaveK]

I also had this kind of sound caused by a dead cylinder - turned out to be a plug not working, installed a new set and everything was smooth again.

[carter200]

Thanks daveK. Jim remember to "write it like you stole it" ;)