Alright, it is completely air tight, cylinder leak down test held at 55psi, fuel pressure is 48 at prime and 54 when idling, pcv valve has been changed and it no longer has a vacuum leak, i just "seafoamed" the engine, did an oil change, pulled ckp sensor out to "test" it, resistance seems a bit strange on 2k ohm it reads .580, cranking test the 2.53v i have been seeing across the live and signal wires goes from 2.53v to 2.73 and down to 2.64v during cranking with all plugs out.
Now with the engine running the voltage on both signal and live does not change from the 2.53v
All the multimeter can tell you is that there is something coming from the signal wire, but not if it's good or not. The signal voltage is changing many times per second. However your multimeter isn't built to react to rapid change, which is why it displays what appears to be a constant voltage. Only a scope can read the signal correctly, and display the waveform that's used to diagnose if the sensor is functioning as it should be.
My question is still on going, it's not internal, the fuel system goes into ol_fault and fuel trims go to 0, the cel flashes and throws p0300 and p0141 both as stored and pending codes, if everything else is supposedly good, what else can i look at before i have to up this to a dealer only repair?
You are getting a code that says the ECU is not reading O2 from the downstream sensor when it expects to. That makes starving for air, or a plugged cat much more likely suspects. However that brief STFT was very good, and doesn't indicate lack of O2. So I'd be looking at a plugged cat, which can be diagnosed with a back pressure test, or perhaps a cat temp test.
However, one very easy DIY test you can do is remove the upstream O2 sensor (the one on top) from the cat, and see what happens to performance when you do a short run that way. If it runs much better with the upstream O2 sensor out, then the plugged cat is virtually confirmed. I imagine that living in Canada, you can find some place where no one would care if you're running a loud vehicle for a few minutes.
The p0141 code has to do with the o2 heater circuit, and the car has all kinds of power, so would that still warrant a plugged or semi plugged cat?
I was assuming that with a flashing misfire, there is also a noticeable performance problem. But are you saying it's running well even when the CEL goes on? If so, yes that would change what I was thinking.Originally Posted by Z3r0x01
However, you're asking what can be done, and removing the upstream O2 sensor and running is an easy thing to do on these vehicles (assuming you have or can get an O2 sensor socket), so why not try it anyway?
Assuming the cat test shows no change, then the next thing I'd do is replace the downstream O2 sensor. Although it shouldn't change anything relative to the misfire, it should keep the loop closed, and give more STFT and LTFT readings. It's really important to know what those are reading, once the misfiring begins.
If the misfire continues, you can also see what the spark looks like with a good spark tester, and also check the injectors with a noid light. Yes, I know you've hung on a bunch of new parts, but something is causing the misfire, and those things are a part of a systematic diagnostic approach.
I haven't been trying to sound ignorant or rude, when the misfire starts there is no fuel trim readings period both st and lt go to 0.0 and i was also told to try swapping the upstream and downstream o2 sensors with eachother, ie switching them to see if it throws a different code, on the same note, the downstream o2 sensor car harness plug end had alot of corrosion in it, and with everything else i have already done, that may be causing my o2 code
Yes, definitely that corrosion sounds like the cause of the P0141 code, instead of the sensor itself. Perhaps the connector is shot due to the corrosion, and resistance testing would be the way to prove that (either way). I can post the pins to test with your meter, if you want to go that route.
You didn't answer if there is a noticeable performance problem or not, and it would be helpful if you can post that information.
Back in post #39, you wrote: "Fuel trim in st is reading around -3.8 to 0.8, but it stays in cl and once it starts to read LT by then i have the p0300 and it goes to ol_fault, but before ol_fault the LT reading is around 0.8"
And that's why I wrote that the fuel trim was briefly ok, indicating that the air/fuel mix is not a problem. (at least during that short amount of time).
There is no noticeable performance change other than higher fuel consumption, and the lt and st fuel trims when it goes into ol_fault both drop to 0.0, and yes i would like to test that connector to see if it might be shot. I'm also being told to change out the ckp sensor where it looks like corrosion in the sensor plug, but if thats not the issue why change it?
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