Upstream vs Downstream O2 Sensors

[HiHoeSilver]

What I find interesting about the drive log above is that generally it looks as though Bank 1 was reading more lean (higher fuel trim command), so the PCM was throwing more fuel at that bank than Bank 2. Not sure what's up with that.

To be honest, I haven't been very consistent with my data collection. A log here, log there, sometimes on the stock tune, sometimes on the Diablo, pre-B12, post-B12. LOL I think now that it seems to be running solid on the stock tune.....and after I get the new O2 sensors in it, I'll get a little more serious about building up some good objective logs where I can start really looking at the data to see if it points at any trends.

The one thing you forgot on your list of "lean" Causes is vacuum leaks. Obviously this could affect one side more than the other depending on the location of the leak. That being said, if you have a vacuum leak and you get on the gas, the trims will go negative to correct as you are getting farther away from the vacuum conditions at idle. If the trims are getting worse with throttle, you can look at a fuel delivery problem. (looks like what yours is doing from a quick glance). I admittedly have not read every book you've written in this thread as of writing this, but I do intend to. This stuff is as fun as it is frustrating!

Your low(ish) fuel pressure aside (which may account for some of your first 7% of + LT trims), one bank getting worse than the other points to a dirty /clogged injector on that side.


I think. Lol


Edit: I have read everything now. Sounds like you're gaining on it. I think you're smart to do the injector service. You idea of using the tuner to "test" them is intriguing.

 

[Dannydean]

Don't expect much excitement.... LOL Fuel Pressure, both banks STFT, both banks LTFT, and rpm. Started at idle, then after a bit ran it up to 1000rpm for a bit, then 1500, then back to idle.

What setup has gauges like this. Looks nice. Daddy wants.

 

[Dannydean]

My 07 denali has the miss at idle also. And I've entertained the idea of changing the injectors. I also heard somewhere that the stock injectors were barely enough. And with long tubes, high flow cats, diablew tune cold air intake. I thought about stepping up to 40s. Cause every once in a while I'll get some detonation under heavy load or full throttle.

Also I get vapor lock in the summer when pulling the boat. Once it dies I hook up the fuel pressure gauge and bleed off the air bubbles and it fires right up, then off I go again. Fuel pressure Is steady around 59 and fluctuates when there air bubbles in it. Fairly new plugs and msd wires. Just pulled a plug to look at it and its white as paper. Looks lean. Just curious if injectors would help it. Egt readings get up to 1800+ under heavy load, seams high to me.

 

[Hi-psi]

What setup has gauges like this. Looks nice. Daddy wants.

Torque Pro on my Android phone with a generic Bluetooth OBD-II dongle.

My 07 denali has the miss at idle also. And I've entertained the idea of changing the injectors. I also heard somewhere that the stock injectors were barely enough. And with long tubes, high flow cats, diablew tune cold air intake. I thought about stepping up to 40s. Cause every once in a while I'll get some detonation under heavy load or full throttle.

Also I get vapor lock in the summer when pulling the boat. Once it dies I hook up the fuel pressure gauge and bleed off the air bubbles and it fires right up, then off I go again. Fuel pressure Is steady around 59 and fluctuates when there air bubbles in it. Fairly new plugs and msd wires. Just pulled a plug to look at it and its white as paper. Looks lean. Just curious if injectors would help it. Egt readings get up to 1800+ under heavy load, seams high to me.

I read in a couple of places that the stock L92 injectors (31's) were small for the application......but, after digging further, the ruling consensus seems to be that they're just fine until you get into heavy mods as long as they are performing at capacity. You can fairly easily switch to the injectors that came in the 6.0 from the 2500HD trucks which are 41's, but you'd of course need a completely new custom tune to accommodate the larger injectors. All of the injectors from any of the FlexFuel engines will work and are much larger also, but they are physically shorter injectors so you have to get some adapters for them to work.

1800 EGT is crazy high, especially if for longer than just a second or two....and you're right, heavily white plugs indicates a lean condition.

What plugs are you running?

Also, what are/were your thoughts on the Diablew tune? Was it a noticeable difference from the canned 91/93 Diablo tune?

 

[Hi-psi]

BTW, Torque Pro on Android is pretty cool to have. It functions as a pretty good basic OBD-II scanner, data logger, and there are some add-ons for extended PIDs for some makes/models. You can set up all kinds of different "dashboards" with various gauges, picking any PID for the input. Or you can log it all to a CSV file to analyze on your computer, or you can used a plug-in they have called Track Recorder which turns your phone/device into a dashcam, recording video/audio, and then you can overlay gauges displaying any PID's data on top of the video.

Here's an extremely boring video of that feature from several years back when I was chasing a torque converter lockup issue on my F250 diesel.

 

[Dmascari1984]

BTW, Torque Pro on Android is pretty cool to have. It functions as a pretty good basic OBD-II scanner, data logger, and there are some add-ons for extended PIDs for some makes/models. You can set up all kinds of different "dashboards" with various gauges, picking any PID for the input. Or you can log it all to a CSV file to analyze on your computer, or you can used a plug-in they have called Track Recorder which turns your phone/device into a dashcam, recording video/audio, and then you can overlay gauges displaying any PID's data on top of the video.

Here's an extremely boring video of that feature from several years back when I was chasing a torque converter lockup issue on my F250 diesel.

That is pretty sweet


Sent from my iPhone using Tapatalk

 

[Dannydean]

Torque Pro on my Android phone with a generic Bluetooth OBD-II dongle.



I read in a couple of places that the stock L92 injectors (31's) were small for the application......but, after digging further, the ruling consensus seems to be that they're just fine until you get into heavy mods as long as they are performing at capacity. You can fairly easily switch to the injectors that came in the 6.0 from the 2500HD trucks which are 41's, but you'd of course need a completely new custom tune to accommodate the larger injectors. All of the injectors from any of the FlexFuel engines will work and are much larger also, but they are physically shorter injectors so you have to get some adapters for them to work.

1800 EGT is crazy high, especially if for longer than just a second or two....and you're right, heavily white plugs indicates a lean condition.

What plugs are you running?

Also, what are/were your thoughts on the Diablew tune? Was it a noticeable difference from the canned 91/93 Diablo tune?

The plugs are ac delco 41-110. As far as the tune goes. It was more than a slight difference. The over all drivability is excellent.
But the main Reason I got the personalized tune was because of the mods I had. I didn't want to be running lean. But the plugs look the same, before and after the tune. So either o2s or injectors.