HELP! I give up.

It seems that the fuel level is a parameter that is considered in the OBDII miss- fire monitoring scheme on some if not all. Other general related inputs presented as food for thought are:
Coolant temp in correct range
Engine load signal in correct range
Engine speed signal from Crankshaft position sensor in correct range
Engine is running (obvious)
Engine has been running for a specified time
Vehicle speed sensor in correct range.

The main function of the OBD system is to protect the cats and make sure the engine is running in an emissions compliant mode. When the ECU cannot bring the running conditions into line it sets a code and the search for the cause begins. If you don't have it yet, go down to Advance Auto or similar and get "Haynes Techbook OBDII & Electronic Engine Management Systems " book. It's number 10206. It really helps older guys like us understand these systems. It's an interesting read and unlocks many of the mysteries.

The knock sensor is a peizo electric device that emits a fixed frequency when the engine is running normally. When knock occurs, the frequency changes and the ecu tries to compensate. The manual specifies the knock sensor resistance between terminals at the sensor of 120-180 ohms at 68 degrees. "If the result is not as specified, replace sensor" it says. To me, this type of signal implies perfect circuit/connector continuity.

I hope this helps you in your search. I hate to give up too.

 

Thanks Troyken! Do you think I have a bad knock sensor that just isn't performing up to snuff but not setting any codes? I mean, it kinda makes sense that the phenomena doesn't occur until I put her under a load bearing situation. I was just ruling out the knock sensors because I never got a code indicating that. Those things are a bitch to change on these Taco's. Maybe while I already have the intake off I should just go a little deeper and change those bad boys out. What do you think?

 

The code you posted, P0333, is "knock sensor no. 2 circuit, high input (bank 2)" That is the drivers side. Since it is so hard to access it may be better to get some more expert hands on diagnosis at this point. I'd hate for you to throw more money and time at a maybe. If you were to find the need to change it at some point, I'd use oem parts though.


The knock sensor responds to detonation (pinging) by retarding the ignition timing.

 

I agree with you. The PO333 code was a result of the rat chewing the knock sensor wire at the connector. I repaired that assuming that the knock sensor was fine. I have thrown more money at it than I've wanted to at this point. It's one of those problems where the high tech doesn't tell you what's going on. Frustrating.

 

Now that I think about it, retarded ignition timing will take all the power out of the engine as you described. BUT, is the sensor malfunctioning or is it sensing real detonation for some other reason and retarding the timing properly in response. We don't know that.

The best bet may be to get a mechanic to hook up a scan tool and go for a ride with you. He can monitor fuel trims , timing and other data and see whats happening in real time.

 

That's a great idea! I may do that tomorrow if they can break away. At least it might give me something real to chase!

 

Good luck !! I think you are on the right track. Keep us posted would you?

 

I sure will! I hope this thread will keep someone else from throwing a boat load of money at theirs.

A BIG THANK YOU TO ALL OF YOU GUYS FOR YOUR HELP AND INPUT!!!

 

If you have an iPhone or Android phone, this tool plus a $10 add-on software package gets you good visibility into the ECM's activities:

https://www.scantool.net/obdlink-mxp/

For my '07 4Runner, additional PIDs related to this:

Ignition advance (degrees)
Knock Correction Learning Value (degrees)
Knock Feedback Value (degrees)

Plus a whole list of other useful data such as Long Term Fuel Trims, individual cylinder misfire counts, etc. Very useful for DIY'ing.

 

If it ran good, then the wire got munched, then it didn't run good, it stands a good chance that t has something to do with that wire

 

Christian06, Do you think the wire was made wrong? I haven't considered that but I guess it's a possibility. I would think if it were made wrong or had excessively high resistance that it would throw a code as if there was no continuity at all.

What if it's reading bank 1 as bank 2 and vice versa? If it was made wrong and did that, the ECU doesn't see anything wrong but may get false readings. I don't know, just Swagging it.

 

I'm pretty sure it's right though. This is what I ordered:

 

I’d check the resistance/voltage reading between the knock sensor and ECU with an ohmmeter. To see if the circuit has a short in it.

I chased a misfire code on one of my cars before, which drove me nuts for a while until I figured it out. A tiny spacer from my intake tube got sucked into my #3 intake manifold runner. Case in point I was throwing a misfire code on cylinder number 3.

 

That part# retails for $28, and wholesale price is $19 without shipping. If that eBay seller isn't a known Toyota dealer, you likely got a counterfeit part and it's suspect.

edit: and look at the one rating it received...one star.

 

I'd avoid running any resistance testing with the ECU connected to the harness. On some automotive ECM/PCMs, the current associated with resistance testing can be enough to damage the driver chips.

 

If that is an "aftermarket" harness it may be suspect. I thought originally that the O/P repaired not replaced the harness. The best action would be to disconnect both ends if possible and test continuity at least. If the sensor itself was gnawed that may be suspect also. I'm not sure what the signal level change between normal and "knocking" is. Any abnormal resistance in the signal path is bound to cause trouble. Again, a scan tool should reveal the issue as a first step before tearing into it again.

 

I’ve test numerous switches in various cars for years in this way. Ignition switches voltage, fan switches, fuel pumps, and etc....
Just to see if they are getting power, or the recommended voltage at the switch.

 

It could possibly be, just unhook it and run a couple tests with a volt meter, that will tell eliminate that, next would be the sensor itself, it may have shorted do to the munching of the wires

 

Thanks guys! I will check the resistance of the wire while I have the intake off. IF I can get it unplugged without taking those damn cooling pipes out again. That's the hardest part of the whole project. I still think a shorted sensor would throw a code though. Maybe bad resistance in the wire wouldn't or if for some reason the wire was made backward like I said before, reading opposite banks. Not sure how I would check that unless I could unplug one and key it on to see which bank would be called out. The only review was that some knucklehead ordered it and it didn't fit his car. Not the sellers fault there in my opinion.

The problem is so intermittent that it drives me crazy. Like this morning when pulling out of my driveway, I gunned it because I kinda pulled out in front of someone . It didn't act up at all!!! It accelerated perfect. But, when I get in it this afternoon it may try to lag on me upon acceleration. I know when I get on the interstate it feels like it's missing terribly. It may be an engine temp related issue. When the engine is hot something goes awry.

 

Have somebody explain to you the difference between voltage and resistance.