OliverLS

Here's the CSV file with the factory reset. The temperature needle was at the lowest but the coolant temperature was at around 45 celcuis or 113F since the car was started early in the morning.

OliverLS

That is some very interesting information, worth taking a look at, I'll check that part on my car.

Aus430

Yes it is - however let's address the O2 sensors first.

OliverLS

Agree, it's clear that there is a problem with the O2 sensors.

Aus430

So here are the charts from reset data

Everything looks fine on the intake side of things

some telling data here - look at B1 O2S2 - further discussion below

See the computer beginning to compensate - it really doesn't take long for it to start testing compensations

A couple of observations - notice how the computer starts applying compensations relatively quickly at around the 2minute market and then apply long term trims a little while alter at the 3:40 mark when the engine is above 70 degrees and after the first rev.
also notice the secondary o2 sensor data relative to the compensations.

Ok, so what I can now see from the data:

Good news:
- The sensors on the intake side of the engine look fine ie - Temp, Maf and throttle position. They all seem to be behaving properly. Also your thermostat is working as per normal too.

O2 sensors -
the secondary O2's are telling an interesting story
B1O2S2 - goes from rich at idle to lean when revved and then eventually ends on being lean
B2O2S2 - is largely lean with a couple of spikes to rich

The problem (at least one problem)
Now.
B1 sensor 1 is broken - do check the wiring but the sensor can't be trusted. (Obviously)
B2 sensor 2 - you can see it's patterns changing as the computer starts pulling fuel. I think it is giving false rich data when compared to the data behaviour in the sensor 2

From experience with my friends LS430 where he had a faulty knock sensor in one of the banks. over a couple of days we eventually got to the root of the problem which turned out to be faulty MAF data, which was being compounded by the broken knock sensor on bank 2. One of the most revealing insights was when we swapped the sensor wires to see what would happen, in the process of step by step elimination over a few runs we discovered that the engine computer is programmed to tune bank 2 relative to Bank 2 first. It uses bank 2 as the benchmark.

Meaning....... if a sensor is giving incorrect data on bank 2, it will incorrectly mess up the tune on bank 1 by referencing the reading on bank 2.

In this case I think your sensor 1 on bank 2 is giving false rich reading, causing the computer to pull fuel from both.

The reason I say that is the response from the B2O2S2 doesn't match what the first sensor is reading. The problem is then amplified as the computer is already ignoring the broken bank 1 sensor which is giving nonsense data...

Next steps.

1. Have you checked the wiring for the B1 O2S1? If broken, please fix and re-run the test (after reset)

2. If the wiring is ok - then please replace the dirty plugs and at least b102s1 (preferably both O2S1's) with new Denso's or OE. I can personally vouch that the ones from Rock Auto work great.

OliverLS

Thank you so much for your help, answering your question:

1. I've tried following the wiring, it's a bit complicated, very cramped in there. Tomorrow I'll try and get to the bottom of all of this.

I do have a couple of questions:

1. Other than looking at the wiring itself, should I use a multimeter and check the readings coming from the wiring? I have to imagine that if I am unable to find any physical damage I should be able to know what's wrong by using a multimeter.

2. Should I check the Bank 2 O2S1 resistance?

3. Do you think I could have a bad ECU? I know it's a bit extreme thinking this, but just to be sure.

Aus430

This is necessary.

1. - Yes check the wiring.
For continuity of each wire from plug back to the ecu
Between wires to make sure there is not shorts between circuits.
Also I'd check each of the wires for any V current Ignition on, engine off (write the values down).

You could check the O2 sensor itself for resistance, Though if there is no damage to the wiring, the sensor is caput. but you may work out how it broke.

2. Comparing it to wiring B2 would be a good precaution (write the values down). At least B2O2S! is pretty easy as the plug is easy to get to at the front of the engine, though you will have the same plug separation resistance.
You could check the sensor for resistance and continuity of the sensor if you want to. It may make it obvious if the B1O2s1 is shorted inside.

Tip: Handy to have a friend at the ECU end to help with the multi meter rather than getting up and down from under the car.

I don't have the wiring diagram on hand to verify which colour wire ends where on the ecu plugs - You can probably find it in the read first pinned post area of this forum.

I'd say 99% unlikely that the ECU is bad at this stage given everything else seems fine (throws error codes, gives predictable reading and responses vs known good data etc.).

OliverLS

Okay guys, this was the day that I looked into everything, after all of the failiures of the previous days I'd say today was a success (kind of).

Lets look at Bank 1 Sensor 1.

First, I did this test.

The test says that at 20° celcuis, the resistance should be 11 to 16 ohms.

The temperature of the O2 sensor was around 31° celcuis or 88°F, the resistance I measured was at 11.7 ohms (I'd say it's in range, but please, give me your opinions).

Also, I measured continuity on the wiring harness.

Here I measured 126 ohms.


Here I measured 1500 ohms @2000k on the multimeter so I guess its 1,500,000 ohms

This was all in Bank 1 Sensor 1.

Moving on to Bank 2 sensor 2 (very interesting stuff here).


Upon doing some physical inspection I found this wire to be in very bad condition.

I measured the resistance on the wiring harness on Bank 2, and this is where the wiring in the last image is broken, still measured around 1,500,000 ohms just like in the other bank.

Here, this part of the wiring harness measured around 132.3 ohms

On this wire, I measured 1.4 ohms, I'm not sure why it's measuring this or if it's supposed to measure anything at all since from what I recall, on Bank 1 only two wires were measuring resistance.

Also on Bank 2 I did the same test I did on Bank 1 measuring the O2 sensor resistance and at the same temperature I measured 17.9 ohms, which I believe is out of range.

I also tried following the wiring of Bank 1, I really couldn't see any physical damage on the obvious parts of the wiring, there appeared to be no damage on the connector and no damage on the ECU.

Please give me your opinions and if you need me to do other tests, I can repeat the tests on the wiring harness if you want, If I missed some information.

Also, that wire that is in bad shape, can I solder it with some tin?

Aus430

I don't trust either of those sensors. B1 is definitely broken and b2 is out of spec and I think reading false rich.

I dug out my old ones. I replaced them with new ones when I bought my car and was trying to get to the bottom of erratic long term fuel trims - there is thread here a couple of years ago when I was changing things sensor by sensor.

Turns out the original O2's were working perfectly, but swapping them with new ones it gave me confidence the readings were in fact correct.

I measured both. 13.7 and 14.2 ohms. Its about 23 degrees here this morning.

13.7 on the short cable. 14.2 on the longer one

The old ones have been taking up space in my garage since. As they work, I never threw them away.

If you'd like them I'll post them over. It may take a week or so to get to Panama. If you do pm me your address.

You will need a good O2 sensor socket to change them. I found it impossible with a normal spanner.

As for the harness, were there any shorts between circuits.

OliverLS

Well, I am not sure how to look for shorts, I'll do that tomorrow with my father since he probably knows how to look for them (do you have any tips for doing this?) , as for the damaged wiring on the B2 wiring harness, can I solder that wire with tin? Is there a way to fix it? Also, with that O2 sensor socket, did you buy a short socket or a deep socket? Thank you so much for your help.

Aus430

I used one that looked like this.

https://www.ebay.com.au/i/2031651688...89be6ab490f3ba

Aus430

Looking for shorts is simply checking that the wires continuity isn't shorting into wires next to it...

so if you have 4 wires - a,b,c,d fore example. You test one at a time. Eg wire a

Check positive end of the multimeter on a. (Say o2 connector at ecu end)

Then the negative end on a at the o2 connector end, it should beep if your multimeter has that function, or show 0.000 on the ohms setting. Then also check the negative end on b,c &d. They shouldn't show any continuity. Ie the should show o.l. (open load). If any of those circuits show continuity you have a short between that wire and a.

Repeat process for each b,c &d wire.


Also I forgot to ask - was the missfire there after the reset?

OliverLS

After the most recent reset no, no misfire yet. Today I straight up disconnected the B1S1 sensor, started the car and connected my multimeter to the O2 sensor prongs directly, the highest the voltage got was around 0.40V coming straight from the O2 sensor, but of course, on the techstream the B1S2 measured at about 0.97V because the car has to be running as rich as it can. I'll leave some photos of the live data.

As for looking for shorts, I'll have to get longer cables for my multimeter so that I can test the ECU and the cable at the wiring harness, and I'll also have to get a 12V test light, physical damage on the wires, only the picture I sent, I cleaned the wires and applied some electric tape.


At 2500 rpms

Idling (warmed up)

Idling (warming up)

Idling

Aus430

Given techstream is seeing 0.00 volts unplugged it's unlikely to be the wiring harness causing permanent voltage. Probably a short in the sensor itself - which is good easy to fix just replacing the O2 sensor.

So I'd recommend replacing both banks o2s1's. New plugs too.

You can see that computer is running open loop with it disconnected. And yes rich.

OliverLS

I was thinking the same, since techstream doesn't see any voltage I dont think there is a problem on the wiring itself, what is strange to me is why the sensor measured between 0.30 and 0.40 volts when connected straight to the multimeter but 1.27 when its connected to the wiring harness, could a short inside the O2 sensor do that? Maybe a problem inside with the heating element (since it gets voltage) is shorting with the signal wire itself?

I know that sensor has to be bad because the B1S2 is measuring a rich condition, I'm amazed by how complicated modern cars are.

Thank you so much for your help, I'll order those sensors as soon as I can, one more question.

Until those sensors arrive, should I connect the O2 sensor again and run the car lean or keep it disconnected and run the car rich?