hey guys. just curious what does the code 52 do to the engine or ecu when it pops up? does it put it in limp mode? fuck with timing? what? just curious. thanks
Mike
Mike
code 52
- Thread starter supramike7m
- Start date
It doesnt do anything. That code is letting you know the ECU isnt recieving any signal from the knock sensor. It is from an electrical problem in the wiring, but it could also be a dead sensor.
Info that some may find useful and to clear up any confusion:
The knock sensors are piezo elements tuned to a peak of 7 hertz since this frequency is typical of knock. At this frequency the sensor's output is at the highest level. The ecu judges the "strength" of the knock to be at one of three levels depending on the sensor's output voltage. It then retards the timing accordingly ie; if the knocking is strong it pulls a lot, if weak it pulls it a little. When the knocking ceases timing is advanced by fixed angles a little at a time, incrementally approaching a new calculated timing value for the current oparating conditions. If knock doesn't reoccur timing retruns to what it needs to be. If knock does reoccur the process is repeated.
As with all sensor inputs the KNKs signals are input to the ecu through a current limiting resistor. This is how the ecu monitors them. A short or open in the KNK signal while the engine is running under load (or at a high speed after a short time, about one or two minutes) results in a code 52 being set and the MIL being illuminated. At the same time the fail safe system sets ignition timing at a fixed retard angle to prevent engine damage, but no more than 10 degrees from calculated. (Calculated timing is initial timing + basic advance angle + corrected angle, either advanced or retarded).
In additon the ecu constantly monitors the sum of basic advance angle and corrective angles and prevents them from being greater or less than the following: a max advance of 35 to 45 degrees and a min advance of 0 degrees.
As an aside knocking is not the only event that causes correction angles. A high coolant temp signal, high altitude, cold idle, acceleration immediately following deceleration, AC on, and many other things all cause corrective angles to occur, either in retard or advance. In short the ESA system is pretty intelligent and always acting in subtle ways many times not felt by the driver.
The knock sensors are piezo elements tuned to a peak of 7 hertz since this frequency is typical of knock. At this frequency the sensor's output is at the highest level. The ecu judges the "strength" of the knock to be at one of three levels depending on the sensor's output voltage. It then retards the timing accordingly ie; if the knocking is strong it pulls a lot, if weak it pulls it a little. When the knocking ceases timing is advanced by fixed angles a little at a time, incrementally approaching a new calculated timing value for the current oparating conditions. If knock doesn't reoccur timing retruns to what it needs to be. If knock does reoccur the process is repeated.
As with all sensor inputs the KNKs signals are input to the ecu through a current limiting resistor. This is how the ecu monitors them. A short or open in the KNK signal while the engine is running under load (or at a high speed after a short time, about one or two minutes) results in a code 52 being set and the MIL being illuminated. At the same time the fail safe system sets ignition timing at a fixed retard angle to prevent engine damage, but no more than 10 degrees from calculated. (Calculated timing is initial timing + basic advance angle + corrected angle, either advanced or retarded).
In additon the ecu constantly monitors the sum of basic advance angle and corrective angles and prevents them from being greater or less than the following: a max advance of 35 to 45 degrees and a min advance of 0 degrees.
As an aside knocking is not the only event that causes correction angles. A high coolant temp signal, high altitude, cold idle, acceleration immediately following deceleration, AC on, and many other things all cause corrective angles to occur, either in retard or advance. In short the ESA system is pretty intelligent and always acting in subtle ways many times not felt by the driver.
I dont have Toyota engine control system manuals here, but I dont think their ECU will retard with out the correct signal. And yes, it is a closed loop ignition system.
Not sure what you mean by "correct" signal. ESA does all sorts of retard corrections based on various sensor input. Knock isn't the only one. What I wrote wasn't lifted directly from the manuals but was paraphrased from it. I could break them out and look but I know this stuff pretty well having been an "owner circa 1987" 
. Since you worked for Toyo it should be familiar as I'm referencing their service training materials.
. Since you worked for Toyo it should be familiar as I'm referencing their service training materials.
Lol, you mean like that guy on Gilligan's Island? (Showing my age there I guess). I'm just trying to pay back all those who took the time to teach me.
Speaking of Gilligan's that brings up a question I've struggled with for years and never have been able to answer: Ginger or Mary Ann?
Speaking of Gilligan's that brings up a question I've struggled with for years and never have been able to answer: Ginger or Mary Ann?
??
How about the wave form generated by the sensor. That will retard the timing. No signal, no retarding from code 52, which was what the question was, I think. Seems like there is DTC for knock with out retarding, not sure when that started.
Of course spark is controlled by many factors. I wasnt refrencing anything you had said.
I see now. A failure in communication is all it was. Upon reading the post again it seems you were talking more about diagnostic actions than normal actions. It seems you were implying that a fault in the knock sensor circuit would only set a code and illuminate the MIL without any correction being applied to timing. In other words an open or short in the knock sensor circuit does nothing other than report a fault. Is that what you were stating? If so the books say you're wrong.
Btw (to kill two birds with one stone) I understand you weren't saying I do but I can't remember the last time I read a car magazine, shitty or not. Nor am I a mechanic. I've never worked on cars for a living because frankly I've found them not much of a challenge and too much manual labor. I'm a lazy "you can earn more money with your brain than your muscles" kinda guy. Doesn't pay well enough for my taste either
Btw (to kill two birds with one stone) I understand you weren't saying I do but I can't remember the last time I read a car magazine, shitty or not. Nor am I a mechanic. I've never worked on cars for a living because frankly I've found them not much of a challenge and too much manual labor. I'm a lazy "you can earn more money with your brain than your muscles" kinda guy. Doesn't pay well enough for my taste either
Last edited:
I have had that code. I am going to say something but at the end it cost me a slot rodknock. How? easy.....I drove the car like that for months beating on it and everything and never changed the oil. The richen mixture cut down the oil which I learned from one of the threads turns your oil to kerosen. WHICH IS A NO NO FOR OUR MOTORS:3d_frown: From what I read the kersoen to mixture destroys our bearings. I feel like such an ass:nono: even telling to guys how dum I was :nono: And it was already a fresh motor:3d_frown:
"Menage a trois"jetjock said:Lol, you mean like that guy on Gilligan's Island? (Showing my age there I guess). I'm just trying to pay back all those who took the time to teach me.
Speaking of Gilligan's that brings up a question I've struggled with for years and never have been able to answer: Ginger or Mary Ann?
"The first thing I'll do when I get back home is bake an apple pie, milk the cow, and feed the chickens".
Lol, how can you say no to that? I've made my decision. I mean, just look at her
http://tinyurl.com/3acdn
Lol, how can you say no to that? I've made my decision. I mean, just look at her
http://tinyurl.com/3acdn