Slight miss at idle, poor MPG, sooty exhaust pipe, No codes. 250K

Foggy · Nov 14, 2024

Also think about cleaning your MAF.. Running oiled air filters is very common
for some of the oil to get onto the maf.. Clean it.
When was the last time you changed your upstream oxygen sensors????
They are pretty much a maint item anymore.. Good for 100-125K... They should
have been replaced at least once as reg maint since you have 250K. Get the good
ones: GM or ACdelco if possible. Just don't get the cheapo ones
Also would be a good idea to do a reset on fuel trims and ethanol % as mentioned.
The ethanol is calculated "virtually" on our rigs. So if oxygen sensors are crappy
you will get funky ethanol calculations

j91z28d1 · Nov 14, 2024

yes, forgot about maf, I cleaned mine and could see it idling in a different part of the airmass vs rpm map and I don't believe it's ever had anything but a paper filter in it.

o2 are a good idea too, as they foul out over time, especially from how much oil these things suck thru the pvc system. they drift lean and the ecm throws fuel at it. also on these trucks that don't use physical ethanol sensors, fuel trims is what it uses to come up with E% content. so if sensors are reporting incorrectly, it can mess up the math and think it's running e when it's not.

Tozan · Nov 14, 2024

Thank you, I have never replaced those sensors I did clean and oil the air filter not to long ago. I cleaned the MAF when I did the filter I guess I will clean it again. I always say go back to the last thing you touched... That would be the air filter...

Charlie207 · Nov 15, 2024

j91z28d1 said:
yes, forgot about maf, I cleaned mine and could see it idling in a different part of the airmass vs rpm map and I don't believe it's ever had anything but a paper filter in it.

o2 are a good idea too, as they foul out over time, especially from how much oil these things suck thru the pvc system. they drift lean and the ecm throws fuel at it. also on these trucks that don't use physical ethanol sensors, fuel trims is what it uses to come up with E% content. so if sensors are reporting incorrectly, it can mess up the math and think it's running e when it's not.

Replacing my two up steam O2 sensors made a huge difference after my engine swap, and got rid of several DTCs that had popped up related to fueling, which made no sense, but worked. Improved overall driveability as well.

I got the OEM upstream O2s from Rock Auto.

Tozan · Nov 18, 2024

So far I cleaned the MAF replaced the air filter and replaced the up stream O2 sensor. I just did a hunting trip this past week so after my return I filled the tank and will do some driving this week to see if that helped..

I got a 4x4 mule deer on my hunt...

Slight miss at idle, poor MPG, sooty exhaust pipe, No codes. 250K

Foggy

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j91z28d1

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Tozan

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Charlie207

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Tozan

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