P0325 will NOT go away (knock sensor)

[Devbot]

Haven't found anything yet, the only set of wires that needed replaced was ironically the knock sensor harness, which was brittle like glass. Everything else wiggles around freely and looks fairly in-shape - I've actually redone some of the looms because I couldn't stand how they were done; namely the SUPER brittle ones alongside the fuel rails, and didn't notice anything besides some soot and dust

 

[Devbot]

Today it took some doing to get the CEL to come back (thought I was in the clear), now I have P0325, P0330, and P0135...
Anybody have any ideas? There has to be a common denominator in here somewhere. Gonna replace the O2 sensors since they have thrown a code before - but that's about where the correlation stops

 

[jbtvt]

Did you check for short to ground on your knk conductors yet? Seems pretty likely that's what's going on, and that it's intermittent so might not even show up without repeated testing. If it was me at this point I'd just run new shielded conductors, splice to connectors and and cut off the old conductors. It's like $10 and maybe a couple hours work. You've already replaced everything else so even the testing is kinda moot at this point really, the purpose would be to rule out the expensive stuff like the ECU replacement (although if it's automatic that's not really so expensive generally

 

[gamefreakgc]

Swap out the engine harness. Even a junkyard unit would be an improvement.

 

[Gull81]

That is a lot of money for the parts cannon. IACs for Yotas can be real finicky once they get dirty.

Per the O2 sensors: my sister’s best friend drove a 06 Highlander with the 2.4 in it. It would throw the money light on now and then. Called for the ECU to be replaced. The stealership replaced the ECU and upstream 02 sensor to the tune of $1850. Money light came back on. After another $1000 spent at the dealer, she asked me to look at it. Nothing consistent in different freeze frame data times. Turns out that just by moving the rear 02 sensor wire after at least one drive cycle, it would die, then come back to life. Replaced it with a Denso and all was good.

How are the fuel trims, especially long term?

Just wanted to ask a quick question, but I was wondering about the fuel trim - how long does it take to reset if the battery disconnect, and what is considered normal for the long term fuel trim.

 

[LittleCaesar]

Just wanted to ask a quick question, but I was wondering about the fuel trim - how long does it take to reset if the battery disconnect, and what is considered normal for the long term fuel trim.

I would recommend to get the short and long fuel trims as close to zero as possible by first starting by cleaning the MAF and air filter, checking for vacuum leaks, and if the 02 sensors are original (or A/F sensor if ya have one), replace them.

If you don’t have access to a smoke machine but have a code reader that reads live data, see how the fuel trims read after a drive cycle. If the long term value is at least 5% greater/less than the short term at idle, and if you rev up the engine to around 2000 rpms and the trim levels come close to zero as they should be, more than likely there is a vacuum leak somewhere under the hood.

The negative cable off the battery for at least 90 seconds resets the ECU.

 

[Gull81]

I would recommend to get the short and long fuel trims as close to zero as possible by first starting by cleaning the MAF and air filter, checking for vacuum leaks, and if the 02 sensors are original (or A/F sensor if ya have one), replace them.

If you don’t have access to a smoke machine but have a code reader that reads live data, see how the fuel trims read after a drive cycle. If the long term value is at least 5% greater/less than the short term at idle, and if you rev up the engine to around 2000 rpms and the trim levels come close to zero as they should be, more than likely there is a vacuum leak somewhere under the hood.

The negative cable off the battery for at least 90 seconds resets the ECU.

So you are saying if the Trims are +/- 5 of eachother at warm idle, and when I rev to 2k rpm the trims go to zero there is a leak. Do you mean that the trims will add to zero?

Ie Long term trim = 5%, and at 2000rpm and short term fuel trim goes to -5%?

 

[19963.4lsr5]

So you are saying if the Trims are +/- 5 of eachother at warm idle, and when I rev to 2k rpm the trims go to zero there is a leak. Do you mean that the trims will add to zero?

Ie Long term trim = 5%, and at 2000rpm and short term fuel trim goes to -5%?

This it the fuel trim LTFT.STFT. The Long Term is the whole number and the Short Term is the right of the decimal point.

Everytime the short term hits +-30 it adds or subtracts a 1 to the Long Term value and then zeros out the short term value.

Long term between 10 and -10 is what most refer to as normal.

What is your MAF reading at idle? That does a good job of telling you if any combustion air is bypassing the throttle body.

My two 97’s run zero for the LTFT most of the time but the highest I’ve ever seen on either one was 3.


Sent from my iPhone using Tapatalk

 

[Devbot]

Swap out the engine harness. Even a junkyard unit would be an improvement.

I thought about this after the new ECU failed to fix it, but i dont have the first clue where these wires start and end up. How hard of a job is it?

 

[LittleCaesar]

So you are saying if the Trims are +/- 5 of eachother at warm idle, and when I rev to 2k rpm the trims go to zero there is a leak. Do you mean that the trims will add to zero?

Ie Long term trim = 5%, and at 2000rpm and short term fuel trim goes to -5%?

For a general understanding, yes. Zero or close to it is ideal. The older autos get the more likely you will see a small vacuum leak due to age, but unless there is a tear or forgets to reattach a hose, it probably won’t trip the money light. Fuel pressure also plays a role here.

10% or less between trim levels and you should be fine at idle, thus you should be fine with your numbers at idle.

This is a good read and may help further explain it:
MAF Sensor Testing Methods - Tire Review Magazine

 

[gamefreakgc]

I thought about this after the new ECU failed to fix it, but i dont have the first clue where these wires start and end up. How hard of a job is it?

That's a hard question to answer. I can rank it in terms of hardest jobs I have done, 1 through 10. 1 meaning an air filter replacement and 10 being complete engine swap and rebuild. I'd rate removing and re-installing an engine harness a 5, since it's for both the engine and the transmission. The engine part actually isn't that bad, since you can leave the lower engine harness in place (alternator, starter) and only replace the main harness. You can disconnect the ECU and just shove the whole harness into the engine bay and just go one by one following wires and taking them off. No two connectors are alike so you can't mess it up. You do have to pull the upper intake to disconnect the fuel injectors. The auto transmission is what will give you the most trouble since there's no space between the transmission and the floorpan to disconnect those connectors and they corrode something fierce. I had to use mirrors and pliers on mine.

You'd also have to find a harness from your year and drivetrain. So a 98 4WD isn't the same as a 98 2WD, which isn't the same as a 99 2WD, etc.

 

[Devbot]

Thanks for the info, sounds like quite a bit of work and money. Considering I've dumped a lot of cash into this already I'm gonna continue to keep prodding around first and hope I can catch a short in progress. From the knock sensor connector to the ECU initially measured less than 0.2ohms, maybe I just need to try over and over

Edit: forget to mention that the car now idles better (only high on a cold start) and OBD shows no retarded spark despite the codes, so that's a plus

 

[jbtvt]

A short may not affect continuity to the ECU but it may still affect the signal. If a rat chewed the wires so that the signal and grounded shielding wires are touching but the signal wires are still intact, you would get continuity to the ECu, but also continuity to ground. Depending on the resistance in the ECu circuit, it is likely that more current will got straight to ground, which could potentially throw your ECU for a loop and trigger a code.

Continuity tests should be done after depinning the wires from the connector, do a search and you'l see how to do it, or at least unplugged from ECU. It isn't a good idea to test for continuity while connected to sensitive electronics as the voltage used to test can damage components.

 

[Devbot]

I hear you. Once the weather clears up I'll tackle it again, been pissing rain over the past few days

 

[Devbot]

Where would be the best place to find a spare ECU harness? Pick n pull shows no 4runners anywhere close

 

[jbtvt]

car-part.com

Might do better searching for other parts besides harness on year you need and then calling to see if they'll pull or you can pull yourself. I know from experience that wiring harnesses aren't a big mover so they might have the truck you need on the yard but not bothered to list the wiring harness

edit: although I'd still start with just rewiring the couple wires you suspect are shot, of tracking down the flaw in your existing harness, whole replacement is a PITA, much easier to cut and splice what you need

 

[LittleCaesar]

Where would be the best place to find a spare ECU harness? Pick n pull shows no 4runners anywhere close

PM fellow member [MENTION=78895]DeathCougar[/MENTION]. He is in the Evergreen state as well.

 

[Devbot]

although I'd still start with just rewiring the couple wires you suspect are shot, of tracking down the flaw in your existing harness, whole replacement is a PITA, much easier to cut and splice what you need

That's more or less what I'm starting to get at - from what I understand they have to come from a nearly identical vehicle and trying to find a harness for a Californicated '00 SR5 4x4 specifically could take a while. Local hardware store sells lots of shielded wire I could use to replace what's there but I'm still figuring out how to properly fix them to the connectors.
The other problem is determining which wire is giving me hell; given that it's been quite a few codes (0135, 0325, 0330, 0420; knock and O2 sensors) then it seems like it's unlikely to be purely the knock sensor wire, and I feel like the combination of codes has to help allude to this. At least that's my take. I'm clearly no electrician.
Thanks for the help everybody, btw. Much appreciated. Just my damn luck that 99% of threads on this issue either come to a halt or end with "took it to the shop lol"

 

[jbtvt]

Just my damn luck that 99% of threads on this issue either come to a halt or end with "took it to the shop lol"

"be the change"

Shielded wire is basically a coaxial cable. Just tie a length of regular wire into the shielding/sheathing wires, I'd use solder but might be able to get away with a crimp connector as long as you check connections, wrap other end of wire around a tec screw anywhere on body and shoot it in. Main conductor connects like any other. Heat shrink and/or 2 coats liquid electrical tape to insulate

Thinking, it's interesting that all the codes you mention are related to a fluctuating/oscillating voltage signal to ECU. I wonder what the signals are compared to internally. Maybe there's some error in the reference signal for either volts or...time signal (is hz even a thing in dc?) Have you checked how many volts your regulator I putting out?

 

[Devbot]

I cant say that I have, but now I have a bigger problem. Hood cable has broke and now I cant get inside the engine bay. So now that has to be fixed, if it can be. Was able to pull on the cable to get inside once but its stuck good now. I'll have to jump back on this gremlin after I sort this out.
The build quality on these vehicles is so piss poor, it's starting to become impressive.
EDIT: thankfully these cables are <$20 from vatozone