shansethp

I have a 95 3.0. Noticed my engine bogging or missing and ran codes got the code 52 knock sensor code. Read everything i could find, to me it was saying either need new knock sensor, another sensor in a new position or just clean the sensor and ponytail from old one might do the trick. Problem is i have never seen any pics as to what the sensor looks like or is located. I dont know what im looking for in the engine compartment or where to look even. also what is my motoor actually doing? i can drive pretty slow and it does ok but if i give it too much gas it backfires and misses. Is it dangerous to drive in this condition?

scope103

Yup. Thar's a lot of baloney about code 52 around these parts.

The ECM slowly advances the timing until the engine starts to knock, then it backs off to assure that the knocking stops. It can tell it's knocking with a signal from the knock sensor. But what happens if the ECM keeps advancing the timing but never hears anything from the knock sensor? OMG, somethings wrong! I may have advanced too far already! So the ECM retards the ignition to avoid pre-detonation (which can easily blow a hole in a piston), and lets you know with a code 52.

Code 52 does NOT mean your engine is knocking. It means the ECM hasn't heard from the Knock sensor. As a result, the ignition is set way retarded to protect the engine. What does that mean? Bogging, missing, runs like crap. Dangerous? You can end up with a very very hot exhaust, but other than that you can certainly limp home. No power, terrible gas mileage.

The Knock sensor is right in the middle of the engine block, underneath the lower intake manifold. So you're not going to see anything until you remove a few (a lot) parts.

The sensor itself is almost never the problem, instead the wiring goes. And the pigtail is in the most hostile location imaginable, so it is certainly a mess. Replacing that will probably do it, but you could have wiring problems elsewhere as well. Cleaning the sensor does nothing. A new position for the sensor is just voodoo; some claim it works, I don't believe it.

Good luck!

shansethp

thanks for all the info, best most clear answer ive ever received!! Okay so which side is it on? Im guessing passenger as that would def be the hardest to get to?!?! You dont have any pics of what i'm looking for do you? thanks man!

scope103

Um, the middle. Let me suggest that this will take a few minutes to sink in. You're not going to pop the hood, lean in, and see the knock sensor. Think "replace the head gaskets." You don't have to actually remove the heads (or the exhaust), but pretty much every other step is in there.



This will give you an idea of what you're in for. http://www.ncttora.com/fsm/1990-1995...e/cylinder.pdf You only need to go through step 28.

shansethp

ok thanks! looks like its underneath the intake then! crap! looks like i'll be taking a couple days off of work to tackle this! hey i really appreciate the help man!!!

shansethp

ok well one other question, im def going to try and replace the ponytail to the sensor. i guess i should just replace the sensor as well? is there a way to test it you know of? i hate to replace it though and it not be bad but to do all that work and not replace it seems dumb as well!

scope103

I can't argue with the logic of replacing the sensor, but $140 might make you think twice. http://www.toyotapartszone.com/oem/t...615-50010.html

And I might as well say it now. Your problem is probably in the wiring. But it might not be in the pigtail. Others have had to jury-rig a shielded wire to run from the pigtail to the ECU.

But you are definitely on the right track. If you get to work on this job, think in advance of the gaskets you'll need. And the crush washers for the fuel lines. You don't want to be one of those guys re-using old gaskets because you forgot to get them.

shansethp

yeah i thought about the gaskets and such, im lucky i have an extra vehicle so this isnt super time imparitive! i really appreciate the help though!

shansethp

One other question, it looks from the photo the wire is mounted to go through the head or is it just laying there for photo purposes? I took a look at my engine the other morning and didnt see where this wire came out and tied into! Any help?

scope103

There is a notch in the head. The wire goes through that notch, and a little piece of sponge rubber fits into the notch with it to keep the wire from moving around.

So it will "come out" between the head and lower intake manifold. It's in there with the driver's side injector connectors.