Knock sensor issues
 

Morning gentlemen, I'm looking for guidance on replacing or if another way to repair the knock sensor on a 1993 3.0, 2wd 4runner. I know it is under the intake manifold and hear it is quite a job to replace. My question is, is there more than one Knock senor. or just one?- I hope it's not one of those stupid questions. Are there any concerns I should worry about when removing the intake manifold or other parts when doing this job? Any help would be greatly appreciated. Thank you...

If you've done any searching on this site, you've probably seen that the MOST likely cause of your problem is a bad "pigtail." The "pigtail" connects to the knock sensor, slips under the lower intake manifold, and connects to the harness near the injector connectors. You WILL need to replace that. The knock sensor itself is very tough, and unlikely to fail, but no one will question if you want to replace it just to be sure.

To remove the lower intake manifold you will need to remove the fuel rail. The crush washers are one-time-use; you MUST replace each of them. I've never found any place to get them but the dealer, but they are cheaper than dirt.

You might as well be prepared for this to NOT fix the problem. If the wiring from the pigtail back to the ECM is damaged, your problem might be there instead. Replacing the pigtail alone is probably enough, but one never knows.

Because removing the lower intake manifold is work, there are many who hope to bypass that by installing a new knock sensor somewhere else completely. Like on the lifting hook. Why would Toyota bother burying the knock sensor so deeply in the engine when dangling it outside of the engine would work? Notwithstanding that, there are some on this forum who have claimed to have gotten that to work. O-kay.

Good luck!

Scope103, thank you for the help again. One more question, if I replace the pigtail do I have to remove the intake manifold to get to it?

Yes. You will be removing your plenum, fuel rails, and manifold. Its not terribly hard, just a long job