Chasing P026D

[daigljk]

I am chasing down a P026D DTC and rather than taking the "Parts Cannon" approach, I'm trying to diagnose the problem using what knowledge and tools I have. I like tinkering and learning

After looking for obvious air and/or vacuum leaks, I focused on the MAF sensor to start the trouble shooting. I looked online to try and determine expected operating range for the 3.0 MAF sensor with no luck. I even got a 1 month, DIY subscription to Alldata to try and find the manufacture PID range for the MAF sensor reading.....nada.

Given the 3.0 liter volume of the ecodiesel and based on what I've researched on typical MAF ranges for engine volume of 1 g/s of MAF per engine volume I was expecting to see 3-5 g/s at idle. I am seeing much higher readings. The MAF appears to be operating normally in terms of doubling when rpm is doubled, but overall seems to be reading high which may be causing an overfueling problem leading to P026D.

idle 683rpm = 11.08 g/s
1351 rpm = 20.68 g/s

Could anyone with a 3.0 and scan tool post your idle MAF ranges so I can see what "normal" is supposed to look like?

Thanks in advance for any reply!
2023 JTRD
Jason

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[Waltzforzizi]

I had this problem code. I have the EcoDiesel, it was the he plastic charge tubes were leaking. I had them replaced under warranty. Took it to 2 dealers before they figured it out. 1ST dealer was s strait up a stealership, trying to upsell and they pretty much killed my batteries. 2nd one figured it out in about 2 weeks and tested it, problem has been gone for 2 months now. IF it wasn't under warranty I would have upgraded to the aluminum ones, I think afe has them, just my opinion. though.

 

[daigljk]

Thanks Waltzforzizi for the reply. My jeep has already spent enough time at the dealership for oil cooler replacement, fuel pump replacement, timing cover oil leak etc. I'd like to try and solve this mystery myself before giving up and bringing back to stealership Any MAF readings would be appreciated.
Jason

 

[Gregj]

According to my iDash at 740 rpm it is 2.2 LB/M and at 1600 rpm it is 5.9 LB/M, idk how to change it to g/s .
Gregj

 

[daigljk]

Thanks Greg!
2.2 lb/min = 16.6 g/s
5.9 lb/min = 44.6 g/s

Your g/s readings are fairly close to mine given our rpm differences. I'm not convinced yet I have an MAF issue. Appreciate you playing along

 

[Lost1wing]

My p026d on another brand ( gm) was my nox1 sensor. It was sooted up and was giving a stuck value. Same cp4 same Bosch ecu. You might want to look at you nox sensors and see what they are doing.

 

[rharr]

Thanks Greg!
2.2 lb/min = 16.6 g/s
5.9 lb/min = 44.6 g/s

Your g/s readings are fairly close to mine given our rpm differences. I'm not convinced yet I have an MAF issue. Appreciate you playing along

If your jeep has been screwed with time and time again aka timing cover, Hp fuel pump ect.. All that is right next to the charge tube, and during one of those times maybe a tool or sharp corner of something has put a hole in it.

I would see about pulling the tube and looking very closely.

 

[daigljk]

Thanks for the input guys! I'll keep hacking away.

 

[Lost1wing]

The nox sensors act like a gas car O2 sensor. If you have one not working right, you could be overfueling or underfueling. That could trigger a p026d. MAF as you know triggers the same code, overfueling or underfueling due to the amount of air sensed by the MAF sensor. Again, this is GM. I believe works the same with the 3.0. It's easy to see if the nox values flux or are stuck (steady or implausible).

 

[daigljk]

Thanks Tim! Yes, I'm starting with MAF/MAP at the front then working my way back to the NOX and 02. It's kind of fun sorting through this stuff and really trying to understand how each component works individually and as a system. My Jeep only has 15,000 miles and I could easily bring it to the dealer. But I would be at their mercy and miss out on the opportunity to further my understanding of mechanics

 

[djthumper]

I had this problem code. I have the EcoDiesel, it was the he plastic charge tubes were leaking. I had them replaced under warranty. Took it to 2 dealers before they figured it out. 1ST dealer was s strait up a stealership, trying to upsell and they pretty much killed my batteries. 2nd one figured it out in about 2 weeks and tested it, problem has been gone for 2 months now. IF it wasn't under warranty I would have upgraded to the aluminum ones, I think afe has them, just my opinion. though.

I had the same issue a couple of years ago.

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