P0442 MIL

[kbuskill]

I will.

I did see in the clip @Fless posted the guy said to clean the MAF, along with resetting the trims. Makes sense, I will also do that as well.

My MAF might be dirty as I had forgotten to change air filters and when I changed it the other day, it was really bad. I have been on fire roads and 4X tracks a lot in the last few years, really dirty environments.

Also, I too changed my O2 sensors recently. I did get the OE units and they seem to be working fine (hopping way down and up).

I haven’t gotten any codes from this stuff, other than the code for the loose cap. If it pops back up, with the cap tight, I will report that as well.

I just went out with my Tech 2 earlier and tried to test my EVAP system by pulling a vacuum and seeing how fast it decayed.

It wouldn't pull a vacuum on the tank. Upon further inspection the purge solenoid wasn't functioning, it was stuck closed.

I went and got a replacement and swapped it out and now it is functioning correctly. I was able to pull a vacuum on the tank and seal the system and the rate of decay on the vacuum was very slow so I think that must have been my issue as far as the P0455 code was concerned.

It wasn't that there was a massive/gross leak it was that the solenoid wasn't allowing a vacuum to be pulled on the tank so the ECM figured there must be a huge leak not allowing vacuum to build.

I am not certain that this is in any way related to my ethanol % being out of whack but hopefully it will get rid of that pesky P0455 I have been dealing with.

Just FYI the purge solenoid was full of charcoal pellets from my old canister. I can shake the solenoid and get pellets out of it..

I blew the line from the purge solenoid to the canister out recently, from front to back while the line was disconnected from the canister but evidently the pellets had already made there way up to the solenoid.

 

[kbuskill]

I also made this video showing my fuel trims and what the O2 sensors are doing.

Keep in mind that I had just reset the Ethanol % right before taking this video and when you reset the ethanol % it appears to reset the fuel trims as well and it enables fuel trim learn.

My point in taking this video was to get others opinions on the readings from the O2 sensors.

If you notice, Bank 1 Sensor 1 seems to drop down below 100 more frequently than Bank 2 Sensor 1.

You can disregard the down stream O2 sensors since they have been disabled in the tune and are not physically there.

Any and all feedback is appreciated.

I am not trying to hijack this thread just trying to get to the bottom of our collective problem.

 

[wsteele]

I also made this video showing my fuel trims and what the O2 sensors are doing.

Keep in mind that I had just reset the Ethanol % right before taking this video and when you reset the ethanol % it appears to reset the fuel trims as well and it enables fuel trim learn.

My point in taking this video was to get others opinions on the readings from the O2 sensors.

If you notice, Bank 1 Sensor 1 seems to drop down below 100 more frequently than Bank 2 Sensor 1.

You can disregard the down stream O2 sensors since they have been disabled in the tune and are not physically there.

Any and all feedback is appreciated.

I am not trying to hijack this thread just trying to get to the bottom of our collective problem.

No hijack for sure. I am caught up in Easter dinner with the family, but will dig into this stuff tomorrow.

I think I probably can record my live data with the O2’s for comparison.

 

[wsteele]

So here is a pic of my O2 data. I will have to figure YouTube or Vimeo out for uploads to post the video I took.

It looks like my Bank 1 Sensor 1 does dip below 100 occasionally (after it was up to full temp never below 91 that I could see), B2S1 seems to stay above 100 (like a low of 117?). B1S1 definitely dips below 100, like every 5-10 seconds.

It was interesting that it looks like one of my S2 heaters is not working as well as the other, as they were way apart until everything got really warm (or maybe one of my cats is marginal).

Oh and Ethanol content has not moved above 3% yet. I have not cleaned the MAF yet.

 

[kbuskill]

So here is a pic of my O2 data. I will have to figure YouTube or Vimeo out for uploads to post the video I took.

It looks like my Bank 1 Sensor 1 does dip below 100 occasionally (after it was up to full temp never below 91 that I could see), B2S1 seems to stay above 100 (like a low of 117?). B1S1 definitely dips below 100, like every 5-10 seconds.

It was interesting that it looks like one of my S2 heaters is not working as well as the other, as they were way apart until everything got really warm (or maybe one of my cats is marginal).

Oh and Ethanol content has not moved above 3% yet. I have not cleaned the MAF yet.

View attachment 275395

It won't recalculate the ethanol % until after you refuel with at least 3 gallons of fuel and drive at least 7ish miles.

 

[wsteele]

It won't recalculate the ethanol % until after you refuel with at least 3 gallons of fuel and drive at least 7ish miles.

Got it. Probably won't happen today, busy with getting the irrigation restarted.

Plus, I need to learn how to post videos on YT.

 

[wsteele]

Here is the clip of the O2 sensor outputs, I hope...

 

[kbuskill]

Here is the clip of the O2 sensor outputs, I hope...

Looks about the same as mine I believe.

Maybe there is nothing wrong with my O2 sensors after all.

My plan, at this point, is to run this tank down low, reset the alcohol content again,, and then top off with ethanol free 89 again and see what calculation the ECM comes up with.

Hopefully that will get things back on track.

Of course, even if it does, I am still going to be paranoid about it getting out of whack again so I will probably continue to monitor it.

I wish my Kenwood had a gauge for the ethanol %... that would make it way easier.

I wish you could input custom PIDs into the Kenwood like you can with the Torque Pro app, that would be sweet. Someone could probably hack it, but not me.... now if it were Android based

 

[wsteele]

Looks about the same as mine I believe.

Maybe there is nothing wrong with my O2 sensors after all.

My plan, at this point, is to run this tank down low, reset the alcohol content again,, and then top off with ethanol free 89 again and see what calculation the ECM comes up with.

Hopefully that will get things back on track.

Of course, even if it does, I am still going to be paranoid about it getting out of whack again so I will probably continue to monitor it.

I wish my Kenwood had a gauge for the ethanol %... that would make it way easier.

I wish you could input custom PIDs into the Kenwood like you can with the Torque Pro app, that would be sweet. Someone could probably hack it, but not me.... now if it were Android based

I am going to follow a similar route. Run it down some, check the recalculated Ethanol percentage (which I will post), reset it after a fill up with Ethanol free and repeat.

I am also going to try and debug why the B1S2 and B2S2 are so far apart when it is warming up.

I wish I knew what a normal S2 voltage is just after a cold start, while it is warming up.

 

[kbuskill]

I am going to follow a similar route. Run it down some, check the recalculated Ethanol percentage (which I will post), reset it after a fill up with Ethanol free and repeat.

I am also going to try and debug why the B1S2 and B2S2 are so far apart when it is warming up.

I wish I knew what a normal S2 voltage is just after a cold start, while it is warming up.

Sorry I can't help with that since my downstream O2s are no longer there.

I'm sure you probably know this but the downstream O2s play absolutely zero role in fuel trims.

 

[Fless]

Interesting subject, and I've been reading up. This article might shed some light on what to expect.

https://www.aa1car.com/library/o2sensor.htm

What I've been reading is that, generally, the mv reading should move around between 100 mv (lean) and 900 mv (rich), but the desired value is around 450 mv. Obviously the sensors are always changing, which is the point of their function.

If you're seeing consistent values lower than 100 mv, I would think that the sensor might be somewhat out of range (weak?) or there might be a problem on that bank. It might be worthwhile to swap the two that are in their respective positions to see if the pattern follows.

 

[wsteele]

Sorry I can't help with that since my downstream O2s are no longer there.

I'm sure you probably know this but the downstream O2s play absolutely zero role in fuel trims.

I frankly have always been a little fuzzy on the role of downstream O2 sensors. Clearly, the ECU monitor for cat function uses it, but beyond that it seems like a function of reporting things after the fact. Maybe their only function is to report when a cat quits being effective?

 

[kbuskill]

I frankly have always been a little fuzzy on the role of downstream O2 sensors. Clearly, the ECU monitor for cat function uses it, but beyond that it seems like a function of reporting things after the fact. Maybe their only function is to report when a cat quits being effective?

That is correct. They are essentially Catalyst monitors and when the cats stop being effective they tell the ECM to throw a code.

Upstream O2s control your fueling.

 

[jj88]

I've got a long term P0442 code on a 2003 blazer... and its NOT the gas cap. 1 point for @PNW VietVet =)

I think its the rubber tubing to the gas tank from the fill port though. Not sure. Need a smoker.

 

[OR VietVet]

I've got a long term P0442 code on a 2003 blazer... and its NOT the gas cap. 1 point for @PNW VietVet =)

I think its the rubber tubing to the gas tank from the fill port though. Not sure. Need a smoker.

That evap system is a source of many complaints. I have recommended before and will do it again, "Replace the whole system along with the cannister." I have seen too many stories here about guys pulling their hair out trying to fix one piece at a time.

 

[OR VietVet]

I frankly have always been a little fuzzy on the role of downstream O2 sensors. Clearly, the ECU monitor for cat function uses it, but beyond that it seems like a function of reporting things after the fact. Maybe their only function is to report when a cat quits being effective?

The fuel/emissions systems do not go from open loop to closed loop without the oxygen sensors and catalytic convertors working properly.

 

[wsteele]

The fuel/emissions systems do no go from open loop to closed loop without the oxygen sensors and catalytic convertors working properly.

It would be interesting to know what those downstream O2 values have to be to trigger closed loop, in post #24, bank 2 sensor 2 doesn’t seem to be functioning yet (engine just warming up), but the system is running in closed loop.

 

[OR VietVet]

For sure, the sensors have to reach a certain temp before functioning properly. Then they have to be able to "switch" fast as they calculate what is being fed to them and then sending out info to ECM so adjustments are made.

 

[wsteele]

For sure, the sensors have to reach a certain temp before functioning properly. Then they have to be able to "switch" fast as they calculate what is being fed to them and then sending out info to ECM so adjustments are made.

Right, but as it pertains to open/closed loop, it didn't seem to matter when I was warming my engine up that Bank 2 Sensor 2 wasn't reporting an accurate number to affect it going into closed loop. It would be interesting to know exactly when the downstream O2 sensors have to be working properly for it to affect open/closed loop.

Reviewing that clip, the Bank 1 Sensor 2 didn't seem to be properly switching yet as well. I wonder how the downstream sensors do affect open/closed loop.

 

[OR VietVet]

It's the front sensors that do most of the work. They are cold started, get a rich fuel mixture and at that point they are not even reading things. They don't read till they heat up to a certain point and then they will feed info to ecm to go from open loop to closed loop. Then the rear sensors have also heated up and they tell the ecm the fuel/air mixture percentage that is coming out of the cats and then the ecm makes adjustments accordingly and then the front sensors deal with whatever fuel mixture ratio there is and again feed info to the ecm. The ecm will make adjustments off of that info and again after input from the rear sensors. I hope I spell this right, the fuel/air mixture the ecm is looking for is 14.7 parts air to one part fuel. That is called
stoichiometric. You want to see the rapid switching with the sensors when you are seeing live stream info. I recently replaced all 4 sensors with GM sensors when my Bank 1 Sensor 2 went bad. Eventually I will do both cats. 135k miles on my rig means some things just need to be replaced to count on the rig.