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You can use cylinder #1 COP or fuel injector on channel 2 as your identifier to determine which cylinder is your #1 cylinder, then count the compression events by firing order to determine the remaining cylinder numbers. There’s probably a lot more ways to do this.
I would probably simply use an inductive pickup over the COP (I believe this is how Matt did it), but if you have a DIS or distributor you could probably put a second clamp on the plug wire.
Certainly not a vacuum leak.
Does the engine misfire all the time, or is it only misfiring when your voltage drops to 12v like you mentioned? Is this the same with the rich condition, or is that also only at -20% LTFT when it is misfiring?
The voltage dropping definitely interesting and I would probably start with what could be causing your voltage to drop like that if it is occurring at the same time as your misfire, though it may be a symptom of whatever is causing the misfire and not the cause. However, I would gather more data first:
Is there anything that consistently causes that to happen? If that voltage drop is a reproducible variable you can start tracking down why it’s happening. What is actually happening during the misfire, is it a loss of spark, mistimed spark, fuel injector dumping fuel? What do your LTFT and STFTs look like during the misfire?
Also, The Garage (Repair and Diagnostics) would be the proper forum to post this in as opposed to The Litter Box (General Discussion).
I could be wrong as electrical is still something I have not gotten enough experience in, but it looks like there’s a short between pins 2 and 3.
If I understand correctly your pin 2 to battery negative should have no potential difference, you should read 0v (unless you have a bad ground, which is another possibility now that I think about it) but now read 5v.
Additionally, your potential between pins 2 and 3 is now 7v instead of 12v. 5v + 7v = 12v
Maybe someone else can chime in here to see if I’m on the right track. Do you read a resistance (as opposed to open) between pins 2 and 3?
P0420 and P0430 codes are usually pretty accurate. The cat should “consume” remaining oxygen in the exhaust stream, meaning that the downstream o2 sensor should show rich in most conditions. If you’re getting oscillation on your downstream sensor it’s pretty likely your cat is damaged.
If there has been an issue on bank 2 for a long time this could be why you have damage to your bank 2 cat, but not on your bank 1. I would definitely start figuring out why bank 2 caused damage to the catalytic converter before replacing it.
This is probably not a vacuum leak (such as an intake gasket like you suggested) because you’re going leaner at higher RPM, if it was an intake gasket you would expect to see a fuel trim improvement at higher RPM when the engine is making less vacuum (Assuming we’re only dealing with one issue here).
It’s important whenever you are looking at fuel trims that you are looking at them over a range of RPMs and adding the STFT and LTFT numbers together to get total fuel trims.
Good idea on the partially blocked fuel filter, I remember watching a video about Volvo boat engine fuel pumps that were known to do this with paint chips from the inside of the fuel tank. Definitely quite a few possibilities on this one.
I’m fairly certain the P0430 would be set by what the downstream o2 sensor reads in comparison to the upstream sensor (in this case, a wideband), and would not be based on the fuel trims. However the conditions causing fuel trims could contribute to the problem.
Is the STFT/LTFT better on bank 1, or is it the same? If you have a bank 2 misfire occurring then unburned fuel will not be registered by the o2 sensor, also potentially causing catalytic converter damage. Is there any other drivability issues? What is the downstream o2 sensor reading at cruise vs WOT? I would start by looking into why you have a lean condition at high RPM, if it is bank specific that will narrow your possibilities.
Also, are these total fuel trims, or just STFT? It’s always important to look at both.
Also note, I was mixing up two bits of information on the “emulated” narrowband reading, the voltage readings are different on a wideband sensor and are in fact “made up” as explained in the wideband sensor video. I was thinking of AEM wideband sensors which have the capability of being wired in to an ECU to emulate a narrowband sensor so that you can just replace the factory o2 sensor instead of welding in another bung.
If I recall correctly from the wideband air fuel sensors video (might want to check that one out!) there should be a PID that emulates a narrowband oxygen sensor, but I don’t remember for sure. So far I have not had to deal with them.
I would also try to find out what conditions set a P0420/0430 on Toyotas of that year.
Are there any other conditions that would be contributing to those conditions like an exhaust leak, misfire, or burning oil on that bank? It could be that the cat is working well enough during highway cruising conditions, but not otherwise.
You have a ton of different codes that could be related or not with no data to go with it. No one can tell you what this means other than what the codes are for. This could be as simple as a bad computer ground causing all sorts of issues with the ECU getting good readings.
Are these all confirmed codes or are some of these stored codes?
What data do you have?
This topic is pretty old now, but I just noticed that you posted about this issue in two different topics in two different forum sections. I would suggest posting all of your data in one place and if you’ve found out anything since.
Speculating based on your other post, your fuel trims are going crazy negative during your fuel pressure drop, compensating for rich fuel trims. It sounds like the fuel pressure could be dropping due to the fuel suddenly getting dumped into the engine, causing a rich condition and a fuel pressure drop. Maybe a sticking injector, which could be mechanically sticking or possibly even electrically. Is this engine’s fuel pressure externally regulated? That would be another potential source of fuel leaking into the engine, though I would think it would affect both banks.
One thing you could try is swapping fuel injectors bank 1 and 2 and see if your problem moves to bank 1, or at least this is the direction I would go suspecting a bad injector. However this may not be the correct direction as I can only guess based on what data you’ve posted so far.
