99 7.4 data log help, running rough and rich

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kar1179

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Hello - Hoping someone smarter than i can help me decode symptoms and data. '99 Suburban K2500 7.4
New to me rig - yesterday I replaced the spark plugs (just maintenance) and all 4 O2 sensors (had P0141 and P0161). After, upon restart, it was running incredibly rough and exhaust reeked of gas. there are no codes (other than steering speed sensor, which I already replaced, but that's another topic).
I have a Blue Driver and attached screenshots of logs I pulled - I don't know how to interpret these, but stuff that seems suspect to me are the fuel trims (high?) and timing (not sure what to expect, but it didn't change much from idle to ~2200 RPM). Also, the Mode 6 data (no clue what this is) shows two test failures, but cannot find anywhere to translate what sensors these are.
I also checked the coolant temp log and it looked fine.
After running and revving the engine a bit, the exhaust smelled different - almost like a mild burnt hair smell....
I don't know what to make of all this. Obviously the supposedly failed sensors would be the place to start if I could translate that. And that this occurred when I replaced the O2 sensors seems pertinent as well, but i don't know what to make of it.
Any ideas?
 

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  • Fuel trim ~2200.PNG
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  • O2 downstream ~2200.PNG
    O2 downstream ~2200.PNG
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kar1179

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More screenshots
 

Attachments

  • O2 upstream ~2200.PNG
    O2 upstream ~2200.PNG
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  • O2 upstream idle.PNG
    O2 upstream idle.PNG
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  • Sensors ~2200.PNG
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  • Sensors at idle.PNG
    Sensors at idle.PNG
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kar1179

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Also forgot to add, I checked for vacuum leaks (sprayed Brakleen all around the engine compartment) and found none.
 

Schurkey

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Hello - Hoping someone smarter than i can help me decode symptoms and data. '99 Suburban K2500 7.4
New to me rig - yesterday I replaced the spark plugs (just maintenance) and all 4 O2 sensors (had P0141 and P0161). After, upon restart, it was running incredibly rough and exhaust reeked of gas. there are no codes (other than steering speed sensor, which I already replaced, but that's another topic).
I have a Blue Driver and attached screenshots of logs I pulled - I don't know how to interpret these, but stuff that seems suspect to me are the fuel trims (high?) and timing (not sure what to expect, but it didn't change much from idle to ~2200 RPM). Also, the Mode 6 data (no clue what this is) shows two test failures, but cannot find anywhere to translate what sensors these are.
I also checked the coolant temp log and it looked fine.
After running and revving the engine a bit, the exhaust smelled different - almost like a mild burnt hair smell....
I don't know what to make of all this. Obviously the supposedly failed sensors would be the place to start if I could translate that. And that this occurred when I replaced the O2 sensors seems pertinent as well, but i don't know what to make of it.
Any ideas?
I'm no expert in BlueDriver. In fact, most of it looks like Greek to me. I have NO IDEA why they tie "Sensor 2" O2 sensors to fuel trims, and then claim that it's "N/A", for example. Makes no sense. OF COURSE it's "N/A".

Looks to me like the O2 sensors don't respond properly--but maybe that's part of the Bluedriver software, not a genuine problem. The post-catalyst O2 sensors are showing high voltage. That can't be good. Faulty catalysts?

Bluedriver reports fuel trims as a percentage, I'm used to raw numbers centered on 128. But 25% seems like a big change from the original programming. Suspicious. Probably indicates misfire. What do the misfire counters show, cylinder by cylinder?

When you put the plug wires back on, are you sure you got them in the right positions?


I checked for vacuum leaks (sprayed Brakleen all around the engine compartment) and found none.
For ****'s sake, don't do that again.

1. Not all brake cleaners are flammable. If they won't burn, they're USELESS for detecting vacuum leaks.

2. When SOME brake cleaners burn, they produce POISONOUS gas that can really fuuc you up, and for days--weeks--months afterward.

I use aerosol carb cleaner. Some guys use an unlit propane torch.

DON'T USE BRAKE CLEANER.
 
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Schurkey

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I had to look-up "Mode 6". I knew there were ten modes to OBD-2, but I have no idea what each does.


My scan tool just gives me information about the OBD-2 monitors. It doesn't call them "Mode 6"; and each monitor has an intelligible name, not some code that has to be broken. For example, I'm told whether the O2 sensor monitor has run or not run, and if it "passed" or "failed". Same with the evaporative emissions monitor, etc.
 

kar1179

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Thanks guys.
Misfire - There are no misfire counters on this for me to look at, oddly. Earlier today I ordered a Chinese GM Tech 2 clone, should be here by the end of the week, and I can check then.
Wires - I'm sure they are correct. The wire holders are still in place - not sure they would let you cross them, but it'd very obvious if you did.
Brakleen - Now that you mention it, I do recall there are two formulations of Brakleen (chlorinated and non, I think, or something like that?) and i don't remember which I have. I'll find something a little smarter and try again.
Mode 6 - I don't know what that is treated different, all other data is shown in the live feed and with clear names. I found 2 translation charts for ~2004 GM vehicles - one was clearly wrong, the other showed those codes as either EGR or MAF - but I verified both are fine. The Tech 2 clone should clear this up anyhow once it arrives.
 

Schurkey

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Another web site with info about Mode 6.


IF (big IF) the Tech 2 clone works as it's supposed to, you'll throw the Bluedriver in the trash.
 
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