...sensor

Ok so it's been a long week.
Chicken or Egg delimma.
22re, '89 4Runner, A/T. I'm am geting an error code for the kock sensor. Didn't even know, just happened to be setting my idle awhile back and noticed it.

So - do you replace the sensor b/c it's throwing a code, or is its job to throw a code b/c something else is wrong causing the "knock"? Does the sensor actually adjust something?

Why was I setting my idle? B/c it's mighty rough. If I set it at the spec-ed 750 RPMs, once nice and warm, it shakes and rattles the whole vehicle. Engine dosn't sound bad, but when I adjust it by "ear" so that it sounds good, and is more comfy at idle, it's more like 850 or so. Note that at 950(ish)+, it sounds/runs just fine.

Suggestions? Could this be a motor mount issue?

The computer uses the knock sensor to listen for detonation
(spark knock)if the computer senses detonation through the knock sensor it retards the timing enough to stop it.

So - getting a KS code means the best first step is to replace the unit, then? Assuming of course it checks out as indeed plugged in, etc.

EDIT - HOLY CRAP them suckers are pricy. Are they made of gold???
Time to start researchin'...

Yep, check your timing, first and foremost. Vacuum leaks and even a TPS could be at fault, as well.

ignition timing is spot on.
TPS measures out ok.
if it is a vacuum leak (which I won't deny as posisble), i'd think it must be pretty small b/c it does idle ok, just needs to be a little high to be comfy.

I got a knock sensor from drivewire.com for about $183. It was the cheapest price I could find. I initially replaced it with a used sensor but it did not solve the problem. So I got a new one for piece of mind.

Of course, the new one didn't improve the situation either so now I'm diagnosing further. You can read my recent posts on this under "Loss of power - Help".

Any other codes thrown??

Any pinging? And what type of plugs are you running? If they're too hot, you could be running into pre-detonation.

Also, I ran into a similar problem a few years back. It ended up being that somehow the knock sensor had backed out a few threads (don't ask me how) and was affecting the harmonics by either rattling slightly or changing the frequency it picked up by altering the contact length with the block. Either way, I torqued it back down and never had a problem again.

so when did it start idling rough? Last time I heard it, it sounded great and the timing was spot on.

Basically the next time i drove it and let it get warm enough, I noticed it.
If you remember, I had it set kind of high b/c i did it by ear and didn't know. We set it back down to 750 after playing w/ it and yours.
That was also when I noticed the code.

just to clarify, it's rough but only in Drive, i notice it sitting at stoplights. Just being in Park it idles up enough to be barely noticible.
Weather was crappy today, I'll look at the sensor connection itself tomorrow.

All the autos i have driven have the same characteristics, while in park or neutral they will idle higher, than in gear. my thinking is that while in gear the engine is under load weather moving or not, as in park or neutral the engine is not under load. my 2 cents