Knock Sensor Repairs - What did you do?

[gamefreakgc]

Hey, just tried to tackle this yesterday.
Personally my trouble started with a combination of P0171/P0325/P0420. Initially suspected a vacuum leak and couldn't find one, so decided to replace the MAF and that took out P0171 and P0420, but P0325 still persisted. When cleared, the CEL will turn off until a steep grade or other means of heavy acceleration.
I read about splicing the two sensors together to trick the ECU around the code and that this worked for many people - thinking this would be the best step since it was the least amount of work and money, I gave it a shot but to no avail. CEL still on.
Next weekend I'm just going to replace the sensors and harness together and call it good; you might as well if you have to open everything up just to service either one. Knock sensors are a headache that will NOT go away like other codes.

(car is a 2000 SR5 at 282k)

I feel ya. It's a stubborn code that's a lot of work and money to fix and becoming more frequent. I fear this code is going to put a lot of 4Runners out of commission due to the high repair costs vs value of the vehicle.

 

[Devbot]

UPDATE: I am officially a member of the Gremlin Hunting Squad
Today I went through the effort of replacing my knock sensors AND harness together (OEM set) in hopes that this CEL would go away, but alas, P0325 came up almost immediately after 5 hours of work - I'd say within 60 seconds of driving, or around that (and idling for maybe 5 mins prior as I cleaned up the garage.) The harness is not pinched and the sensors were tested prior to installation to confirm no continuity, which would otherwise signal a short. The sensors were tightened down by hand, but not to the ~30lb spec; could this be an issue? I'm not sure what else would be.
I'm nearly at my wits end chasing this gremlin - does anybody have an idea as to what i should try next? Electronics are NOT my forte, so any help at all is appreciated. These 5VZ's are not particularly enjoyable to take apart, so I'd prefer to do it only once more and not twice :dammit::ranger:

Edit: When I took off the old sensors one of them was shot, however it got mixed up on the garage floor before testing and it's unclear if it coincided with the bank 1 code.

 

[gamefreakgc]

UPDATE: I am officially a member of the Gremlin Hunting Squad
Today I went through the effort of replacing my knock sensors AND harness together (OEM set) in hopes that this CEL would go away, but alas, P0325 came up almost immediately after 5 hours of work - I'd say within 60 seconds of driving, or around that (and idling for maybe 5 mins prior as I cleaned up the garage.) The harness is not pinched and the sensors were tested prior to installation to confirm no continuity, which would otherwise signal a short. The sensors were tightened down by hand, but not to the ~30lb spec; could this be an issue? I'm not sure what else would be.
I'm nearly at my wits end chasing this gremlin - does anybody have an idea as to what i should try next? Electronics are NOT my forte, so any help at all is appreciated. These 5VZ's are not particularly enjoyable to take apart, so I'd prefer to do it only once more and not twice :dammit::ranger:

Edit: When I took off the old sensors one of them was shot, however it got mixed up on the garage floor before testing and it's unclear if it coincided with the bank 1 code.

When you say tightened by hand, you mean you put them in hand tight, or just made your best guess at 30 lbft? I also did a best guess since I couldn't get my torque wrench in the with the water pipe in the way. If you did them hand tight though, they will wiggle loose due to heat cycles.

There's only 3 parts to check from the FSM:

1. The sensors
2. The wiring
3. The ECU

You've done the sensor and half the wiring. Time to test for resistance on the harness from the pigtail connector to the ECU, and possibly swap your ECU if you can. I had bought a replacement ECU just in case I had to go that route, was around $70 used on Ebay if that helps at all. Make sure you pull yours to get the EXACT model number, each year had different model numbers. If you have a smart key or key fobs you might have to get it reprogrammed to start though.

You can also de-pin the pigtail male connector and swap the wires around. If the code then jumps to the other sensor, it's most likely a sensor issue. If the code stays the same, it's most likely a wiring issue on the ECU end of things.

Hope that helps.

 

[Devbot]

When I say hand tight I meant with a wrench, approximately guessing. NOT finger tightened for sure
Thank you for the information, ECU was going to be my next step! Just ordered a used one for $100ish, and also an oscilloscope just for the giggles.

 

[MikeDiehl]

Issues after knock sensor replacement

So, I just put my truck back together after replacing both knock sensors, knock sensor wiring harness, fuel injector O-rings, valve cover gaskets, spark plugs, and various hoses... :rockon:

Now, the truck smells like gasoline and the throttle peddle seems stiff.

When I started it for the first time, I let it get up to temperature. The fuel line coupling behind the battery was dry to the touch. No visible leaks around the intake manifold. When I put it in gear, the idle fell to about 750rpm. So, I'm not thinking I have a vacuum, fuel, or coolant leak. But that gasoline smell is... unnerving... :AK47:

Any advise would be welcome.

Mike.

 

[gamefreakgc]

So, I just put my truck back together after replacing both knock sensors, knock sensor wiring harness, fuel injector O-rings, valve cover gaskets, spark plugs, and various hoses... :rockon:

Now, the truck smells like gasoline and the throttle peddle seems stiff.

When I started it for the first time, I let it get up to temperature. The fuel line coupling behind the battery was dry to the touch. No visible leaks around the intake manifold. When I put it in gear, the idle fell to about 750rpm. So, I'm not thinking I have a vacuum, fuel, or coolant leak. But that gasoline smell is... unnerving... :AK47:

Any advise would be welcome.

Mike.

Trust your nose. Did you happen to re-use any injector o-rings or crush washers? They are all one-time use parts and re-using those seals can cause a fuel leak at the injectors.

 

[MikeDiehl]

Trust your nose. Did you happen to re-use any injector o-rings or crush washers? They are all one-time use parts and re-using those seals can cause a fuel leak at the injectors.

Ironically, I took the injectors out JUST so I could replace the o-rings.... Should have just left them alone.. I don't recall seeing crush washers, though. I disconnected the fuel rail at the junction just above the fender well. I didn't mess with the banjo bolt at the end of the rail, if that's what you are referring to.

Last night was the first time I could get under the hood without rain. I was able to visually confirm that the middle injector on the passenger side is leaking up from the base.

Swapping out a rubber o-ring for another seems like a simple task. What could I have done wrong?

Mike.

 

[gamefreakgc]

Ironically, I took the injectors out JUST so I could replace the o-rings.... Should have just left them alone.. I don't recall seeing crush washers, though. I disconnected the fuel rail at the junction just above the fender well. I didn't mess with the banjo bolt at the end of the rail, if that's what you are referring to.

Last night was the first time I could get under the hood without rain. I was able to visually confirm that the middle injector on the passenger side is leaking up from the base.

Swapping out a rubber o-ring for another seems like a simple task. What could I have done wrong?

Mike.

Sometimes the o-rings like to roll off when you press it in. You can test if this has happenend by twisting the injector side to side. If it's smooth it's in right, if it sticks the o-ring rolled off. You can also use a few drops of fuel or oil to get it to seat right (from the FSM).

 

[Black798]

Cheapest place I've found the OEM parts is partsouq.com. All oem stuff. Two knock sensors, harness, and the two lower intake manifold gaskets for 287 shipped and will be here Monday. I'm going to be replacing all the oem stuff after getting a driverside sensor that was stuck on and also adding a standalone knock sensor that's ran off my piggyback so I can actually see the knock count and not just trust the oem ones that are notoriously issue prone with boost.

Hoping with this setup I'll be able to have knock control below 3k rpm and then from 3k up just let the oem stuff do it's thing and monitor to make sure it's all working properly.

In my case when the sensor failed it failed a long time before I got the code. Progressively throughout the day it felt like my low rpm power was going away and the truck really was falling in it's face in boost. Got to the point where I thought I'd melted a plug or something because I couldn't get over 40mph and the truck would slow down if it got into boost. P0330 finally came in and I didn't even bother checking to see if it was intermittent before parking it to take it apart.

 

[gamefreakgc]

In my case when the sensor failed it failed a long time before I got the code. Progressively throughout the day it felt like my low rpm power was going away and the truck really was falling in it's face in boost. Got to the point where I thought I'd melted a plug or something because I couldn't get over 40mph and the truck would slow down if it got into boost. P0330 finally came in and I didn't even bother checking to see if it was intermittent before parking it to take it apart.

That's interesting symptoms. It's almost like the sensor was failing intermittently, long enough to kill power but not enough to throw the light. When mine went, oddly it was the opposite. Light came on and drove just fine for a few cycles. Then after 3-4 starts it'd lose power. If I cleared the light the power would come back again.

 

[Bdnewyork]

Cheapest place I've found the OEM parts is partsouq.com. All oem stuff. Two knock sensors, harness, and the two lower intake manifold gaskets for 287 shipped and will be here Monday. I'm going to be replacing all the oem stuff after getting a driverside sensor that was stuck on and also adding a standalone knock sensor that's ran off my piggyback so I can actually see the knock count and not just trust the oem ones that are notoriously issue prone with boost.

Hoping with this setup I'll be able to have knock control below 3k rpm and then from 3k up just let the oem stuff do it's thing and monitor to make sure it's all working properly.

I've not dealt with partsouq yet; but have used amayama from Japan several times with good results. Yesterday I ordered the following from amayama UAE:

2x: 89615-12090 OEM Denso knock sensors $98.75 ea
2x: 17177-62060 OEM lower manifold gaskets $22.49 ea
Shipping: $23.50

I'd ordered the wiring harness 82219-34010- $28.84 from Conicelli with a bunch of other stuff a week prior. No rush with delivery needed for me as I've chosen to replace these prophylactically as part of the VC gasket, timing belt and SC install work.

I am very interested in your plan for an addl. knock sensor as in input to your mapecu3 for tuning below 3k rpm. I also plan to purchase a map piggyback when I drop to a 2.2 pulley as a next step.

From what I've gathered lately, modern knock sensors (e.g. NTK) are designed to provide flat response from 5k-15kHz to meet many applications and rely upon the engine manufacturer to process the signal to meet the specific need.

I read some stuff on customtacos.com that the 5VZFE knock has a peak frequency of 6.6kHz, so you'd need to do bandpass filtering to create a useful input to the piggyback. Presumably, the OEM ECU has that functionality built in for its own needs.

I found this whitepaper by Texas Instruments very interesting:
How to set-up a knock-sensor signal-conditioning system

And this link for the evaluation board ($149), software and documentation:
Vibration and Engine Knock Sensor Interface

I'm also wondering whether it would be possible to tap onto, buffer, condition and utilize the signals from the existing sensors as inputs to the pigyback.

I'll keep poking around on this and please keep us updated on your findings.

 

[Black798]

I've not dealt with partsouq yet; but have used amayama from Japan several times with good results. Yesterday I ordered the following from amayama UAE:

2x: 89615-12090 OEM Denso knock sensors $98.75 ea
2x: 17177-62060 OEM lower manifold gaskets $22.49 ea
Shipping: $23.50

I'd ordered the wiring harness 82219-34010- $28.84 from Conicelli with a bunch of other stuff a week prior. No rush with delivery needed for me as I've chosen to replace these prophylactically as part of the VC gasket, timing belt and SC install work.

I am very interested in your plan for an addl. knock sensor as in input to your mapecu3 for tuning below 3k rpm. I also plan to purchase a map piggyback when I drop to a 2.2 pulley as a next step.

From what I've gathered lately, modern knock sensors (e.g. NTK) are designed to provide flat response from 5k-15kHz to meet many applications and rely upon the engine manufacturer to process the signal to meet the specific need.

I read some stuff on customtacos.com that the 5VZFE knock has a peak frequency of 6.6kHz, so you'd need to do bandpass filtering to create a useful input to the piggyback. Presumably, the OEM ECU has that functionality built in for its own needs.

I found this whitepaper by Texas Instruments very interesting:
How to set-up a knock-sensor signal-conditioning system

And this link for the evaluation board ($149), software and documentation:
Vibration and Engine Knock Sensor Interface

I'm also wondering whether it would be possible to tap onto, buffer, condition and utilize the signals from the existing sensors as inputs to the pigyback.

I'll keep poking around on this and please keep us updated on your findings.

Definitely will post the results in a few weeks once i get it up and running again. Pretty sure I know the thread you're talking about over on CT, read through that a few times when I was exploring the option of ditching the stock sensors all together.

Also heres the mapecu wiring diagram for the knock sensor setup, it already uses the gm knock sensor processor so that simplifies things. I wonder if you could run the stock sensors through that gm processor to the mapecu and just use them instead of that 3rd sensor. The one thing I am struggling to figure out is how to setup two sensors off that gm system. Not sure if I can just run them both off the same wire or if I am better off doing just one sensor in the middle of the cylinder valley. If I had to pick one side for mine to put the sensor I think the driver side would be best since thats the sensor that failed and leads me to believe the side that knocks the most. Very glad I choose the mapecu over the urd 7th or something, its really nice having a piggyback with this much capability

 

[gamefreakgc]

Is there really a need for knock control below 3K RPM? On stock sized tires (realize if you have larger tires but same gear ratio this could be an issue), I don't spend hardly any time with heavy driving under 3K except when going up the pass on I-80 towards Tahoe. Even then just popping out of overdrive takes care of that.

When I want to go fast, 3K RPM's comes and goes really quick...

 

[Black798]

Is there really a need for knock control below 3K RPM? On stock sized tires (realize if you have larger tires but same gear ratio this could be an issue), I don't spend hardly any time with heavy driving under 3K except when going up the pass on I-80 towards Tahoe. Even then just popping out of overdrive takes care of that.

When I want to go fast, 3K RPM's comes and goes really quick...

My truck is re geared to 5.29s but it weighs a little over 1200lbs more than stock and is twisting 35s. I dont like climbing long passes like on I70 screaming at 4k rpm in 3rd to maintain 60. At that point the blower isnt even making boost so what was even the point of installing it. I like being able to hold 65 to 70 at 2500 to 3000 rpm when climbing most hills. I have a shift controller that allows me to force the torque converter to stay locked and in 4th gear. Works really well and its nice not downshifting on every damn little hill I come across. Basically treat it like my turbo car where boost is what carries me up things and vacuum does the rest. So in my case knock control below 3k rpm is really important

 

[MikeDiehl]

So, I just put my truck back together after replacing both knock sensors, knock sensor wiring harness, fuel injector O-rings, valve cover gaskets, spark plugs, and various hoses... :rockon:

Now, the truck smells like gasoline and the throttle peddle seems stiff.

When I started it for the first time, I let it get up to temperature. The fuel line coupling behind the battery was dry to the touch. No visible leaks around the intake manifold. When I put it in gear, the idle fell to about 750rpm. So, I'm not thinking I have a vacuum, fuel, or coolant leak. But that gasoline smell is... unnerving... :AK47:

Any advise would be welcome.

Mike.

So, last Saturday, I got up early and tore back into my truck. I replaces the o-rings. Only this time, I put a bit of 3-in-1 oil on them. This helped A LOT! It also helped to have the intake still on the engine this time!

I quit around noon because it got too hot outside. Worked on it a bit that evening. Then started again at about 11 on Sunday.

The truck was running by 3:00PM!

So now I have a 24 year old truck that runs better than it has in YEARS! :cheers:

I've been driving it for a week now. No gasoline smell. No CEL. Plenty of power. NO hesitation. Never stumbles. Idles smoothly. Hits 85mph sooner than I'd like to admit.

I'm pretty stoked.

Thanks, all.

Mike Diehl.

 

[19963.4lsr5]

My truck is re geared to 5.29s but it weighs a little over 1200lbs more than stock and is twisting 35s. I dont like climbing long passes like on I70 screaming at 4k rpm in 3rd to maintain 60. At that point the blower isnt even making boost so what was even the point of installing it. I like being able to hold 65 to 70 at 2500 to 3000 rpm when climbing most hills. I have a shift controller that allows me to force the torque converter to stay locked and in 4th gear. Works really well and its nice not downshifting on every damn little hill I come across. Basically treat it like my turbo car where boost is what carries me up things and vacuum does the rest. So in my case knock control below 3k rpm is really important

What shift controller do you have?


Sent from my iPhone using Tapatalk

 

[mikeferg]

add me to the list, I am getting both codes on each side or it was the gas, I never had problems till I filled it up at walmart 2 days ago

 

[Devbot]

I'm assuming you cleared them and they came back? If not, give it a whirl, and maybe once more after you refill the tank if it doesnt work. What's the car and mileage anyways?

 

[mikeferg]

Kept clearing, but comes back very random, even just cruising on a back streets, 2002 with 250k, supercharger.

 

[Devbot]

Kept clearing, but comes back very random, even just cruising on a back streets, 2002 with 250k, supercharger.

Sounding very familiar. Another very easy test - if you're able to - is to swap ECUs with somebody driving a similar vehicle and see what happens (I just bought one off ebay for $100). Unfortunately theres not much you can do without taking the intake apart, so might be best to wait until the tank's empty and toss in some fuel cleaner. If you have an oscilloscope, hook it up and check out what the waveform and frequency is - I forget exactly but it should be in the TSM. If it's too inaccurate, inconsistent, erratic, weak, or generally not within damn good spec, it's not good.
Could try sparks/coils, or injectors, but I assume that probably crossed your mind already.
It's been a while so my memory on it's kinda gone but there's tons of information in my old thread along with many others, I imagine you'll get it done pretty fine. I'm not sure how much a supercharger would affect things, so hopefully it doesn't bug you too much