99SC4Runner

I've got a 99 4Runner LTD 4x4 with a 3.4 which is supercharged with URD fuel mods. I've never messed with the timing or the fuel maps since I bought it from a fellow board member. It has always ran great.

Just a few days ago my CEL came on. I notice when the 4Runner is cold and not totally warmed up, it will kinda mildly bog a little under moderate acceleration. But I can floor it after it's totally warmed up and it will be fine, with no pinging or knocking sounds at all.

My CEL is code P0325 which is knock sensor circuit failure on bank 1 (passenger side). I cannot hear any pinging or knocking at all at any speed or under any load including full throttle.

So I'm wondering if the sensor itself went bad, or is it just the knock sensor wiring harness?

I've ordered a new knock sensor, knock sensor wiring harness, and intake gaskets for a total of $246.

I just wish there was some way to test the sensor before I pull the supercharger and intake off.

Toyota 3.4 V6 knock sensor harness #82219-34010

toytech76

to test the sensor itself you would need to pull everything apart anyways to get to it so, may as well do it right and replace it since you are there. If I was to get that code, I personally would replace the sensor and the harness for the sake of it. That way you wont need to worry about it and worry about pulling it apart again in case one or the other part didnt fix it

ciscojay

I had to do the same thing and just replaced both sensors and the harness while I was at it. That code will throw the ECM into safe mode, full timing retard. That's the "bogging" you're feeling. Hook up an obdII scanner and you'll notice it's pulling quite a bit. Go ahead and do it, you won't be running right until it's replaced.

99SC4Runner

I hooked up my BR-3 scan tool and laptop to the 4Runner a little bit earlier, and it had another code P0330 - Knock Sensor 2 Circuit Bank 2, as well as, the PO325 - Knock Sensor 1 Circuit Bank 1 or Single Sensor.

The P0330 code had never popped up before until today. I was able to clear the codes and so far the CEL light has not come back on.

My question is this.

Does it sound more like it's the knock sensor wiring harness now that it has thrown the codes for both banks, and that it is not isolated to just 1 knock sensor? What is the possibility of both knock sensors going out at roughly the same time?

I read somewhere on a Toyota forum from a toyota tech that 99% of the time it is the knock sensor wiring harness that is the culprit.

I know I can test the knock sensors once I have the intake and supercharger off, but then I worry about down time since I drive my 4Runner to work every day and do not have a spare vehicle. And each knock sensor is $160 so there's $320 there, $57 for the intake gaskets, and $15 for the wiring harness, so that's gonna leave a mark on the ol' budget.....lol

I cannot hear any pinging or knocking whatsoever coming from my 4Runner at any speed, throttle load, or rpm, so this has my baffled as to if it's just the knock sensor wiring harness?

Thanks for you help,
Doug

ciscojay

It's possible that it could only be the harness. The wiring harness sits right on top of the block, exposed to extreme heat and over time I hear they can go bad. If it comes back you're definitely knocking.

FYI you don't have to hear ping or knock for it to happen. It is supposed to throw a voltage back to the ECM when it breaks a threshold vibration or sound. If the ECM gets a voltage from the sensors that are not within spec, it's thinking that somethings not right, ie CEL.

I'm not sure how to test the sensor..might wanna research that to see if you can save yourself some cash.

99SC4Runner

What about the possibility of my timing or fuel maps being messed up for my FTC and my supercharger? I've never messed with them myself since I bought the 4Runner from a fellow board member, but I guess anything can happen right?

Just a thought. I'm gonna hook up my LM-1 and my scan tool and check my maps and see if something doesn't look right that might be kicking the knock sensor into the CEL mode.

MTL_4runner

99% of the time, this is your issue. When I did my HG, the harness fell apart as soon as I touched it so it got replaced. Whenever you pull the manifold and the harness is original, I would suggest replacing it as standard procedure. The knock sensors do go bad but that's far more rare.

99SC4Runner

Okay,

I've got the knock sensors out, but how do I test them? I put my DVM on 2k Ohms for test and put the positive lead on the center pin for the electrical connector, and then I put the negative lead on the body of the sensor (on the side where you put the wrench to install or remove them). I'm not getting any readings from either sensor. Do I need to put the leads on the sensor differently to test them? Do I have to hit the sensor with something while I have the leads on the sensor for it to give me a reading on the DVM?

Also I put the DVM on continuity test and I tested each wire of the knock sensor harness for each side, and I get the solid ding noise from the DVM for each side of the harness. But it could still be bad I guess?

Please let me know ASAP because I have to work on my 4Runner out in the driveway under the sky and I would like to put it back together before dark.

Thank you very much for you help,
Doug

MTL_4runner

Doug, the sensors just get checked for continuity.

@ 2K ohms, no reading = sensor good
(it's easier to check them with the continuity function on the DVM though)

So like I said.......unless you bought a new harness, don't bother putting it back together.

99SC4Runner

Jamie,

Where do I put the DVM leads for testing? One on the electrical pinout on the electrical connector side for the wiring harness, and the other lead goes where - just on the body of the knock sensor (side or bottom)? Does the knock sensor need to be grounded in the engine block for testing and the ground hooked up to the battery?

I did buy the new knock sensor wiring harness, as well as, new intake gaskets from Toyota with the new knock sensor I got from them.


On a side note, since I took off my upper timing belt cover to remove the intake, I noticed that it's time to replace my water pump and timing belt. Yoda-g2 had given me new ones to install when I bought the 4Runner from him.

Can I replace the timing belt even though I don't have the tensioner tool like Snap On sells to relieve tension off of the tensioner to get slack in the timing belt for removal and replacement?

Please let me know ASAP because I'm running out of daylight here and I'll be working in the dark....lol....And thanks for your help.

Doug

MTL_4runner

Answers in red above.

99SC4Runner

Jamie,

Thanks for the help

I tested both knock sensors and I cannot get any Ohms reading or a continuity beep from my DVM, so I'm sure they are both good and that the knock sensor wiring harness is at fault even though it seemed to test fine as it has continuity on both sensor wires. I decided to just go ahead and install the new knock sensor anyway and the wiring harness.

Thanks again for the help,

Doug

99SC4Runner

Well I installed the new knock sensor wiring harness and the 1 new knock sensor for Bank 2 and I drove it to work and back (40 miles) on Monday without any problems and no CEL light, until I got within a mile from my house.

The CEL light came on and I checked it with my scan tool and it's giving me P0330 which is the Bank 1 knock sensor. So now I get to purchase the other knock sensor (at another $145) and take my supercharger and intake off to install it.....ROFL

What a pain in my arse it's been to get this fixed. When you live on a budget it's really hard to cough up $290 for 2 knock sensors, $28 for the knock sensor wiring harness, and then $58 for the intake gasket set......and now I have to pay $3.90 a gallon for superunleaded lately......

Sicarius428

Were you able to resolve the issue? If so what was it because I have a feeling that I am in the same boat as you.
Kevin

99SC4Runner

Actually I've just been driving it with the CEL light on because I cannot afford the other new knock sensor until I get my rebate check from the IRS which won't be until June 6th now....

I put one new knock sensor in and a new knock sensor wiring harness and I have the other knock sensor kicking the light on now, so I'm going to assume that if it was the knock sensor wiring harness, that it would have cured the problem, but it didn't. So I'm thinking 1 more new knock sensor and then it will be fixed.

99SC4Runner

Update.....I got the 2nd new knock sensor from my local Toyota dealer and a new supercharger belt for $150. I installed the 2nd new knock sensor into bank 2 and then I cleared the code with my BR-3 scan tool and laptop.

It's been 3 days now and no more CEL.....so I think I got it fixed with 2 new knock sensors and a new knock sensor wiring harness. My gas mileage came back up too....

BigBallsMcFalls

replace both knock sensors if you are gonna bother to dig in and replace one

99SC4Runner

Well I would've replaced both knock sensors and the wiring harness at the same time, but I'm a Network Admin that is way over worked and way under paid at $28k a year. So I'm on a tight budget and having to pay $4 for a gallon of gas sucks and driving 40 miles + a day to work and back home just blows....

blair1

I just replaced both knock sensors and the harness due to throwing a code for 1 sensor. Put it all back together now it says both are bad. That's 2 new sensors and new wiring. Now both are bad? I don't get it.

ntoracn

The code only tells you what system is out of spec. Your job is to test the wiring, connectors and all components related to that code before replacing any parts. The code only gets you pointed in the right direction.

Good job in reviving a 3 year old post!!