spiderwebbtc

Yes, I got a Code 52. I haven't checked the fuel mix. How do you do that? The spark plugs are all new. I put them in a couple of weeks ago, hoping that would improve the situation. I may have gained a little power but the check engine light is still on. I probably wouldn't be trying to fix this if the transmission could shift into overdrive. I understand from reading this thread that that is a common result of a Code 52.

Thanks for your help.

mattches

"Yes, I got a Code 52."
Do you have any other codes?

"I haven't checked the fuel mix. How do you do that?"
Sorry for being vague. What I mean by checking the fuel mix, is to see if it is running rich or lean. You typically can get a good sense of this by checking the condition of your spark plugs. Do you have the old ones you took out still?
The knock sensor is picking up knocking sounds at a particular frequency. The knock is caused typically from detonation or pre-ignition. These symptoms are typically caused by a mis calibration in fuel system. To which there are many parts.

"The spark plugs are all new. I put them in a couple of weeks ago, hoping that would improve the situation. I may have gained a little power but the check engine light is still on."
Have you tried to reset the computer?

"I probably wouldn't be trying to fix this if the transmission could shift into overdrive. I understand from reading this thread that that is a common result of a Code 52."
Sorry I have not read the whole thread, but I would venture to say that it is not shifting in to overdrive and you have a code 52 because the tps (throttle position sensor) is not calibrated correctly. This will send an incorrect value to the computer, saying to add more gas- causing knocking (detonation) and a value to your trans saying that the engine load can't take overdrive right now. Try checking the tps and reset the computer.

spiderwebbtc

I've only gotten a Code 52.

When I took out the last set of plugs they didn't look like they had had much use. There were no deposits and no signs of high heat. I was surprised that they had 4 electrodes each. Maybe the previous owner was trying to get more power out of the engine.

I have disconnected the negative terminal (and the positive terminal for that matter) several times in attempts to reset the computer and clean out the error code. No luck. I understand you can also remove one of the relays to do the same thing, but I haven't tried that yet.

So how do you check and reset the throttle position sensor? This is a possibility I haven't considered so far. I would love to not have to take the plenum, etc. off again.

BTW Moab sounds like a great place to live if you are into 4 wheeling. I'm in Jersey and the only off roading here is on private land. We have to go to PA to find the nearest off-road park.

mattches

Wow, I did not realize how old this thread was.

Anyways, if you disconnect the battery or remove the EFI fuse you will get the computer to reset. But you have to leave it disconnected for about 1 full minute. I had that problem first time I reset mine, and I just wasn't waiting long enough. Be patient.
As for the TPS, it is on the rear of the throttle body, it's the only thing with wires going to it. You don't have to remove it, but it is easier if you do. But you can get away with just taking the throttle body off, it comes off with 4 14mm bolts. And the coolant lines that go through it and the vacuum too. But it is much easier to take off than the entire plenum. If you do take it off, or the plenum off, be sure to replace the gasket, particularly if it is cracked or broken in any way.
Do you have a manual, like a chiltons? they have a section on how to test it. Otherwise, use this link. It is much more complete than the chiltons anyways its from a fsm from MudHippy http://personal.utulsa.edu/~nathan-b...93throttle.pdf

spiderwebbtc

I recently had to remove the plenum, so I had the battery disconnected for over an hour. The Code 52 message appeared as soon as I reconnected the battery. I'll try to work on the TPS this afternoon. MudHippy must have the same on-line 4Runner manual I have. I've found that Hayes is better than Chilton (better illustrations), but there's nothing like a service manual for detailed information.

mattches

You really might just have a bad sensor or wire or connection then. Particularly if it comes on immediately. What I have been talking about would be something that would happen as you were running it.

spiderwebbtc

Actually, it does not come on immediately when the engine is started. It comes on soon after putting it in gear and accelerating for only a moment or two. I've just purchased a new wire and knock sensor. I'll probably try to install them next weekend.

skozzy

Has anyone taken the time to take some pictures of where it is with minimal hardware removed from the motor. I am a little scared to tackle removing all the intake gear without help, there is just too many tubes and hose and pipes all over the place and with a very bad back I am not sure I could even do it, it would be my luck to start something and end up with a monster job.

I read my poorly written manual to see how to remove the intake but it only mentions the EGR and few bolts on the Plenum. Not very informative.

Otherwise, what options have been found that we can make the ECU think everything is fine. From what I under stand the sender creates a low voltage, has anyone tried connection a small battery or regulated power source to the wire going to the ECU. I don't know of any specs on the sender, so it's all a mystery to me.

mattches

Way to go, just jump right in with both feet!
Have you ever taken your intake manifold off? If not, I will HIGHLY suggest that you be sure to loosen and tighten it evenly as you remove/ install it, and get new intake manifold gaskets! And the plenum gasket too. The last thing you want is to go through all the work, and find out you have a vacuum leak.
Replace the PCV valve while you have the plenum off, and since you have the plenum off, check the TPS setting too.
Keep in mind that you will also have to remove the rear coolant block (bolted to the intake, as well as the center timing belt idler pulley. While you don't have to replace the timing belt, be very careful with it as you remove the center pulley, the lower tension of the belt should be sufficient to keep it tensioned on the teeth of the camshafts, but if you loose the tension on it below the camshafts then you will have to check your camshaft position, timing, and re-tension the belt. Which can turn into a PITA.
OR
I have heard of some guys abandoning the whole stock sensor location and drilling and tapping a hole into the rear engine lift hook. Then just screwing a sensor in there.

mattches

Think I have some pics from last time I had my plenum off. But if you look closely at the drivers side, underneath the throttle body, below the fuel rails, between the rear two injectors, you will see a connector with a wire that goes down into the side of the intake. That is the knock sensor wire.
Why are you wanting to replace it?

skozzy

Thanks mattches, we were just looking for the wire and can't see it, maybe the Australian model has more junk covering it. the whole harness is wrapped in flex tube and then covered again with black tape. Moving the sensor sounds like a plan but I can't even start with that till I find the wire.

This problem started a few days ago, I got an error 41 (TPS) and error 52 (knock), it was 2 days after i was smelling petrol. It runs LPG and Petrol, but for 2 years wouldn't run on petrol (blocked or faulty injectors), when on LPG the fuel pump still runs, turned out injector #2 the o-ring let go and it was pushing fuel out at a high rate. At the time I couldn't see it so I washed the motor and left it to dry, it was after then I got the error codes, I changed the TPS (not cheap here I tell ya), and figured at the time the knock error was from pre-ignition from giving it a boot full, but now I learned its a open circuit in the knock wiring.

So the petrol either stuffed the knock sensor or the degreesing did it (I had the motor hot when I did it).

I called a local EFI service center to get a quote for cleaning the injectors and fuel tank, I guess if I go to that extent it wouldn't be much more work for them to pull the extra few parts off to get to the knock sensor.

I bought it 4 years ago, spend a bundle on it for new tyres, lpg system, new cooling system/fan/idler, power steering, air con, new diff, tinted windows, soon after all that and running out of money it developed the fuel problem with the injectors, not being able to fix it then I just drove it on LPG, since the milage is poor on lpg I havn't gone far from home, so spent a lot on it with plans to have fun and ended up with a machine to go shopping.

Dunno if spending a packet on it now is worth it for a 19-20 year old rig. Maybe I should look at guides for the v8 conversion and weigh up the costs to the fun ratio compared to fixing this or buying a newer one.

I don't supose you have a Toyota Part Number for the Knock Sensor, I would assume it's the same number across the world since the TPS was the same in the USA as in AUS. Also do you know what other Toyotas had the same part. Tomorrow the local wreckers is having a $50 all you can carry special, wrecked 4x4's here are hard to find, but things like camrys and corollas are used as land fill there is so many of them, maybe they have the same part.

spiderwebbtc

I replaced the PCV one of the times I've had the plenum off recently. (I think I've had it off a total of 3 or 4 times in the last month or so.) I will check the TPS. I'm very leary of doing anything with the timing belt. My last 4Runner was a '91 that I lost while trying to change the timing belt. One of the overhead cams turned on its own, resulting in all the valves being bent in a fraction of a second. You can see why I'm reluctant to do anything regarding the timing belt, even if it is only loosening the idler. Can the KNK sensor be replaced with less dismantling of the engine?

mattches

If you want to replace it where it is, then the answer is no. You have to take all that crap off. The center idler pulley runs around the water inlet, and it is mounted to the intake manifold.
The 3VZE, is supposed to be a non-interference engine, meaning that if your belt breaks, then the pistons physically cannot hit the valves. What engine did you have in the 91?

bajatoyp34

hey spider where did you buy your knock sensor and wire and how much i got to do the samething. I have a 91 4runner 3.0

spiderwebbtc

I bought both of them on E-Bay. The knock sensor I got for about $25 and the connecting wire, still in OEM packaging from Toyota, was $20. I don't know if you can find a knock sensor for that low a price, but the guy who sold me the wire had about 10 of them. Good luck.

bajatoyp34

thanks spider i should get my parts tomorrow

ronmar

I don't think it will throw a code 52 because of detonation. It will just retard ignition timing, and perhaps increase fuel to stop the detonation.

From the FSM, code 52 reads as follows:
"With engine speed between 1,600 rpm – 5,200

rpm, signal from knock sensor is not input to

ECM for 6 revolution."

The troubleshooting says to look at the following:

1. O

pen or short in knock sensor circuit

2.•

Knock sensor (looseness, etc.)

3. ECM

The knock sensor is basically a peizio electric mic element bonded into a threaded housing. When stimulated by engine noise, it generates an AC voltage. When measured with an ohm meter it is an open...

I am also getting a code 52, which by it's description indicates to me that the ECU cannot hear the engine run. This tells me that it needs a certain ammount of noise to confirm operation, and excessive noise indicates detonation to which it takes action. If it dosn't get proper feedback when it is supposed to, it assumes the circuit or sensor is bad, stores code 52 and goes to a default "safe" ignition table. Mine has cut in and out a few times while driving, and you can realy see a difference in how well the engine runs with good sensor feedback. I pulled the plenum, and cleaned the connector under the throttle body, and measured the AC voltage(millivolts actually) while tapping on the intake manifold with a hammer. I also measured this same voltage back at the ECU input to confirm a good circuit. Mine is creating AC voltage, but still throws a code 52 after I rev the engine, so mine must not be supplying adequate feedback. I compared it's output to that of a 22RE sensor, and the 3VZ's sensor is only putting out a fraction of the output. About 20MV compared to nearly 500MV for the RE sensor with some good loud tapping...

sam333

Yeh , there is alot of confusion about these codes 52 and 0325 ( both Toyota knock codes).

Like ronmar said the code is not telling you your engine is knocking , in fact if the sensor is working properly you will never know that your engine is starting to knock/ ping( no code).

The code is telling you that the ECM is not recieving the proper signal, called the "normal mode vibration frequency" or "backround noise". This is the signal the knock sensor sends the ECM when the engine is running properly, and if the ECM does not see it, it will retard the timing to the maximum value( fail safe) making the truck run poorly.

This can be caused by an open or short in the knock sensor circuit, knock sensor being loose, or bad ECM.

jcac27

Hello,
I'm new to the forum. Been reading but now have a question to ask. I realize that this thread is old but I'm not able to find the knock sensor wire.

I recently had the head gasket go and had the engine rebuilt. Unfortunately I didnt have the mechanic replace the sensor or wire. Now after its all back togethor and running im getting the 52 error. Id like to try sanding down the contacts on the connector. Is that something I can get at without taking the engine apart? Can someone post a picture of exactly what it looks like on the engine?

Thanks alot for all of the information!

ronmar

The sensor is under the lower intake manifold. The pigtail cable comes up thru a notch in the drivers side of the lower intake between the last 2 cylinders. The pigtail connector connects with the main engine harness right under the throttle body. The connector is round and approximately 3/4" in diameter and aboug 1 1/2" long, dark in color.

It is had to work with under the TB, but the TB comes off fairly easy compared to the upper intake manifold, if you can't mamage to work with it where it is with just the air intake tube removed.

My pigtail was heat damaged right where it comes up thru the manifold and pulled right apart. I replaced the sensor and pigtail and monted the sensor on a homemade bracket on the front of the block near the thermostat. Way easier than a whole topend disassembly...