I've been reading these forums for years and have read alot on this "Code 52" I havnt seen where anything fixed it besides replacing the knock sensor and pigtail has anyone found anotber fix to this code? I just put this engine in the truck a month ago and rebuilt the bottom end. So im sure the wiring from ecm to pigtail is ok being I never had the code before engine swap. Previous owner of engine said heads and hg job wasn't long done. I replaced crank and bearings due to a knock. Truck runs great until it spark knocks then code 52 pops up. I don't understand why its spark knocking even after I've retarded the timing.

 

Have you ever heard of brittle wiring. I have. I had it.

 

Well yes I have thank you... but explain me this my engine spark knocks, the knock sensor corrects it like it should so why would the light come on if it corrected a knock like its designed to do. I may be wrong in my hypothesis.... and thank u for ur help bit im trying to understand how would it correct the spark knock with broken wire.

 

Did you use a Toyota knock sensor, or one from an autoparts store? Did you torque the sensor down? The autoparts store knock sensors do not work with these engines, the signal is very particular. Did you check the continuity of the wiring for the knock sensor? Is the hook you used to mount the knock sensor well grounded? Are the retaining bolts tight? The code for the sensor will will come on if you go over 1600 rpms for more than about 6 seconds if the ECM doesn't receive a signal. The timing is retarded once this happens automatically, trying to put the engine into limp mode.

 

Yes its was a toyota sensor I took it out my previous engine that didn't have the code when I done engine swap. The hook is well grounded but I no I didn't torque it. I connected my meter to the two prongs on the pig tail then to the plug that goes to pig tail and got 0.L whether im doing it right I don't know. I just wonder where the spark knock is coming from or if its related being it stops after cel comes on. Guess im going to have to tear it down and replace it. Gotta have it right before my spring Georgia hunting trip

 

You can tear the top of the engine down, install another knock sensor and pigtail, put it all back together, and still have the same issue. If you have not checked the continuity from the pigtail to the computer connection on the main computer (KNK port on the ECM) you should do this before spending hours on the tear down / repair. The continuity test on your multi meter would be setting the tester to the setting that resembles headphones, touch the two prongs together and get a reading of 0, then put one end at the black wire on the knock sensor pigtail, and the other end at the computer, connector B, pin 5, black wire. Your reading should be very close to 0 as well.

 

Ok i got 0.00 0.01 from knock sensor plug to ecm so the problem lies berween pigtail and sensor correct

 

When I did the test I had the plug that plugs into the knock sensor pigtail unpluged, but left the plug to the the computer plugged up. Is this correct? (Im far from a electrician )

 

I tried everything imaginable prior to going back to an OEM Toyota Knock sensor. Code 52 definately make enjoying the vehicle to do.

 

Yes, that would work fine. Is the knock sensor on the hook a Toyota sensor? Have you checked your timing with the Diagnostic port TE1 and E1 jumped? It should be 10 degrees BTDC with them jumped.
Test the knock sensor: hook up an multimeter to the sensor (looking for milivolts here), run the vehicle, and see if the readings change with acceleration, as it should.
Did you install the knock sensor with a nut threaded on or did you drill a hole and screw it into the hole?
Have you cleaned your injectors? Recommend SeaFoam.

 

I took the sensor off the hook and plugged up back to the original knock sensor. The one on hook was a test hoping to lead me to problem. I didn't set timing with a light which I never have in the past on other vehicles i've worked on. I will do the sensor test in the a.m. after work. No I haven't seafoamed this engine. Kinda weary of seafoam... I have noticed a PAIR REED VALVE gurgle when engine goes from being accelerated to idle, and a small PVC valve hose air leak not sure if those two would make this problem uprise.

 

I just found a very interesting thing related to pinging problem. Open the link below, and a few paragraphs down, look for "Pinging" and the distributor fix.
https://www.yotatech.com/forums/f116...k-3vze-187741/

 

Ok i done a test on the sensor with my meter I it 1.5 and mv at top if screen (I've got to learn more about this multimeter) I got 0.0 when I rev engine it goes negative thats it. It ain't looking good.
That's a nice write up https://www.yotatech.com/forums/f116...k-3vze-187741/

 

I had the Code 52 forever too and ended up fixing it with an externally mounted TOYOTA sensor. Sounds like you did that already though. Just so you're aware though, Code 52 implies that your Knock Sensor system isn't working correctly. It doesn't mean anything about whether your engine has a knock or not. There are only 3 things involved in the Knock sensor circuit ... ECU, Knock Sensor, Wiring. I'd bet on the wiring. Mine is old and brittle and will have to be replaced soon, but it works for now. Make sure you're reading out your wiring correctly or have someone that knows DC circuits do it for you. If your KS is good and your ECU is good and your wiring seems to be good, it sounds like there's a bad connection somewhere. Did you use any sealant on your KS when you installed it or is it just metal to metal?

 

Also, I was just reading my Chilton's and came across this (directly from the book):

"Light spark knock may be noticed when accelerating or driving up hills, particularly with a carbureted engine. The slight knocking may be considered normal (with 91 octane) because the maximum fuel economy is obtained under condition of occasional light spark knock. Gasoline with an octane rating higher than 91 may be used, but it is not necessary (in most cases) for proper operation."

This, however, comes from the manual that tells me to gap my plugs to "0.041." No thank you ...

 

I have completed all of the above testing for my similar problem, Code 52 with High Idle.
History: I had swapped 3vze enignes a while back (I am new, and ignorant to Toyota and now realize I should have done the 3.4L swap) and had this knock sensor issue -- the engine idled ok but was running horribly at driving speeds. So I then replaced the knock sensor(after market) and sub harness(OEM). And it now has the high idle and still shows the Code 52.
According to a multimeter that I used to check continuity, on the ohms setting, I have continuity from the sub harness to the computer. Without testing the sensor in question, I'm assuming the aftermarket sensor is causing the issue with this sensitive system? There is a test to be completed on the system: with the engine running @ 2000 RPM's, and a timing light connected, tap on the exhaust manifold, and the timing should retard.
Thoughts or comments from the YotaTech Toyota Masterminds?

 

Appears to have continuity to the computer?? Did you actually use a multimeter to check this, or just assume?

 

According to a multimeter that I used to check continuity, on the ohms setting, I have continuity from the sub harness to the computer.

 

I recommend purchasing a new sensor from Toyota. I tried several New aftermarket sensors and all of them failed to work!

 

^AMEN!^ ... OEM engine electrical will never lead you astray.