cpljenkins01

i have a 90 3vze and i have tried a new knock sensor and wire and relocated it to the motor hanger and it went away for 100 miles and came back so i give up. i understand all the problems with this idea but i am wanting to know if anyone knows what size resistor i can use to bypass the knock sensor. it not knocking or ticking and its running fine i just need to get my fuel mileage back.

JohnnyCanuck

I understand your frustration, however you could conceivebly jeopordize your healthy engine when people here could probably help you fix your situation. They ground through the threads so make sure you really clean where it threads into. Also there are quite a few threads on this: https://www.yotatech.com/forums/f116...-block-268781/

cpljenkins01

Well I didn't have anyway to thread the mount so I found a nut that fit and put it on I guess that's why cuz I just took it back off and there was oil on it so I cleaned it off and ran A wire from The fire wall to it so it has 2 ways that's its grounded. It seems to be working for now.

JohnnyCanuck

Gj, hope it keeps working for you.

MudHippy

Yeah...don't count on it.

1. It's not possible to bypass the KS with a resistor. It just flat out won't work.

2. Bolting it to the engine hanger is just plain stupid dumb. I'm seriously pissed off at the guy that did that to the 90 I just bought. Because it's constantly throwing code 52 on a consistent basis now. Random, but consistently so. It just keeps popping up about every 2nd or 3rd time I drive the thing. And it has nothing to do with it being grounded well enough. He threaded the hole through the engine hanger and put an acorn nut on the exposed end of the sensor too(holding it tighly in place). That's a pretty far fetched notion anyways. So long as it's touching any bare metal part of the vehicle, it's grounded just fine. So don't expect that double grounding it will fixing anything. Most likely it won't.

I'm not sure exactly why it doesn't work when you bolt it to the engine hanger. Other than, if that was a good place for it to be and function correctly, then Toyota would have put it there in the first place. DUH!!! I figure it's either recieving inaccurate knock sounds, and then producing inaccurate signals in that location(which is making the ECU throw the code). Or just the massive amounts of vibration through the engine hanger itself is producing inaccurate, or negating accurate, signals from it(making the ECU throw the code). Or the vibrations are simply causing there to be an intermittent loose connection at the wiring connector(which is the most likely cause for any KS code).

Regardless of what the reason(s) for it are, I'll be putting the damn thing back where it belongs ASAP. Thanks a lot for that stupid dumbassedness buddy. What a huge time saver that was...NOT!!! Always having to clean up messes I didn't even make. Makes me so fricken mad...

JohnnyCanuck

My '89 had this issue, I use a thread chaser on the block and a die on the knock sensor, fixed my issue.

MudHippy

I'm not saying it can't be caused by a poor ground connection. I believe that. What I don't believe is that you can EVER make one work for any long period of time by bolting it to the engine hanger. I swear to god that's got to be one of the stupidest ideas of all time. I've got all the proof I need to think so sitting in my driveway at the moment.

JohnnyCanuck

I agree, which is why I said why would anyone chance a healthy motor by circumventing the knock sensor.

scope103

While I don't think I have MudHippy's passion on this subject, I, too, can't believe that mounting the knock sensor to the engine hangar is worth a tinker's damn. It's just too far from the location selected by Toyota's engineers, and I don't think it can pick up the acoustic signal it needs.

It's worth reviewing why we have a knock sensor in the first place. The ECU slowly advances the timing as far as it can, and when it "hears" knocking it backs off until the knocking quits. Getting optimal advance at all times. What if the knock sensor just shuts up? Will it keep advancing the timing until the knocking blows a hole in a piston? That would be poor engineering, so if the ECU doesn't "hear" from the knock sensor at all, the ECU assumes the worst and retards the timing in a desperate attempt to save the engine. That retarded timing is why cplJenkins01 is getting such poor performance and mileage. IF there was some way to "bypass" the knock sensor, all you'd accomplish is tricking the ECU into quickly destroying your engine.

Fix it right. It's a true PITA, but any other way is just wasting time.

IMHO.

cpljenkins01

I am just simply trying to get the engine light to go off so I get better performance and fuel mileage. I am about to unplug it and just turn the afm leaner to compensate for the knock sensor riching it.

blueknob

right or wrong, my knock sensor has been mounted to my engine hanger for over a year now with no problems, no code 52, engine running great, I'll fix it properly someday, but for right now its working

scope103

Interesting. I've never heard that the knock sensor had anything to do with mixture. http://www.autoshop101.com/forms/h38.pdf Let us know how that turns out.

MudHippy

Lucky you. I still don't believe it though. Maybe your ECU is broke. Does it throw code 52 when you unplug it?

Don't bother answering that. I probably wouldn't believe whatever the answer would be either.

Sorry. That's just how I'm going to be about it. Nothing you can do to sway my opinion.
Like scope is saying, that line of reasoning is flawed. It might help improve performance and fuel efficiency when it's working correctly. But it has nothing to do with fuel trim. It's simply there to monitor the effects of ignition timing.

https://www.yotatech.com/51990071-post3.html

cpljenkins01

Mudhippy are you telling me that when it throws a knock sensor code that it dont effect the fuel air ratio or timing?

blueknob

I know you don't want to hear it, but here goes, if I unplug it, it will throw a code. when I bought it, it was throwing code 52, I bought a new knock sensor and a new wire, bolted it to the engine hanger, code went away. since my knock sensor can`t retard the timing anymore, I run 93 octane fuel, I have the timing set perfectly, so I get no pinging going up a hill, i can`t explain it I just know it works for me. mud hippy, just wanted to say I thoroughly enjoy the brutal honesty of your posts. thank you for that.

cpljenkins01

I have noticed that if I drive it easy in low rpms it don't send a 52 code. I am going to try to turn the timing back a little to keep the valves from low end rattle and kicking the code.

scope103

Yup, it's not SUPPOSED to throw code 52 below 1600rpm. I'm sure that's not an exact number, so I'm not surprised that keeping it at low rpms will mask the code.

Do you think "low end rattle" has something to do with code 52? And wasn't your problem that the ignition was already set too far back (as a result of the conditions that threw the code in the first place)?

vasinvictor

iTrader: (3)

I've mounted the knock sensor in the engine hook a couple times on rigs I bought. I mount them there until I get a free weekend to remote the top end to replace the wire. Sometimes it works, sometimes it still throws a random code 52. Better than a severed KS wire and being almost undriveable.

I can't believe a seasoned vet like you, MudHippy, would have let such a detail slip by when buying a vehicle.

cpljenkins01

When I drive it and code 52 shows the only difference that I visually see is the fuel air ratio and how it adds more fuel. I do feel a difference also in power loss but I still worrie that it is dumping more fuel. Timing is easier to adjust back a degree or two. I am running at 15 degree right now so if I take it to 13 it may be enough to get rid of my low end rattle and keep it from throwing codes.

AZSPEED

It's not richening it up, it's retarding the ignition which in turn makes it run rich. Mine was a faulty ECU not reading the signal from the ks. Code 52 is ECU not seeing a signal from the ks, when the ks is working under a knock condition it does not throw a code