P0170 fuel trim and CEL

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greiswig

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Well, I made it to Moab and back, and the only major problem I had was destroying one of the new poly bushings in a front lower control arm on one of the trails.

However, I continued to get that same trouble code in an irregular basis the entire trip. I recorded the MAF sensors, because my better half was driving us across part of Nevada and I had nothing better to do. Those graphs look pretty strange to me: often one would go up in value as the other went down. IDK if the computer looks at those signals differently or averages them or something, since they both feed the same throttle opening. I'm grasping at straws here trying to figure out what might cause this P0170 code. So if anyone has great ideas, I'm all ears.
 

ryanjl

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I've got the poly bushings in my lower control arms as well. I notice they make quite a creaking sound when my front wheels articulate. Wonder if there is a good way to grease them?
 

CaliLee

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Well, I made it to Moab and back, and the only major problem I had was destroying one of the new poly bushings in a front lower control arm on one of the trails.

However, I continued to get that same trouble code in an irregular basis the entire trip. I recorded the MAF sensors, because my better half was driving us across part of Nevada and I had nothing better to do. Those graphs look pretty strange to me: often one would go up in value as the other went down. IDK if the computer looks at those signals differently or averages them or something, since they both feed the same throttle opening. I'm grasping at straws here trying to figure out what might cause this P0170 code. So if anyone has great ideas, I'm all ears.
What trails did you end up doing? We were there in April though we took our Raptor instead of the LR4. That turned out to be a huge mistake as we had to leave it at the Ford dealer in Cedar City for the whole trip and rolled into Moab in a rented minivan.
 

Michael Gain

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Well, I made it to Moab and back, and the only major problem I had was destroying one of the new poly bushings in a front lower control arm on one of the trails.

However, I continued to get that same trouble code in an irregular basis the entire trip. I recorded the MAF sensors, because my better half was driving us across part of Nevada and I had nothing better to do. Those graphs look pretty strange to me: often one would go up in value as the other went down. IDK if the computer looks at those signals differently or averages them or something, since they both feed the same throttle opening. I'm grasping at straws here trying to figure out what might cause this P0170 code. So if anyone has great ideas, I'm all ears.

May need a software update, brother. Worth calling the dealer to see if your VIN is part of a PCM update strategy.

Other than that, I would look at the post-CAT O2 sensors. Also, with the engine running, open the oil cap. If there is vacuum, and you idle changes, your PCV membrane is probably torn, allowing unmetered air to enter the intake track.

To answer your MAF question, there will be inconsistencies. The PCM uses the aggregate to calculate how much total air is entering the system.

Remember though, the LR4 uses a MAF and a speed density set-up. I won't pretend to know the software logic, but the PCM will use the MAF (air flow and temperature) and also the IAT sensor + MAP sensor to calculate density; especially under boost. Both these calculations would point to one of the fuel tables within the PCM and instruct the injectors to input the required amount of fuel.

In these complex beasts, your engine may be getting what it needs (air/fuel/spark) but a faulty sensor may be reporting improperly. Thus, triggering the code. The only risk is the PCM slowly adjust the LTFTs. Lean condition will **** the spark plugs and cause pre detonation; rich will foul the plugs and **** your cats.
 

greiswig

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I've got the poly bushings in my lower control arms as well. I notice they make quite a creaking sound when my front wheels articulate. Wonder if there is a good way to grease them?
I thought about fitting zerks to the A-arms, and grinding a channel around the perimeter where the grease might go. But poly requires silicone lube, which isn't easy to find in a tube. I'm not sure this was a lube problem, though: the ******-bearing part of it seems to have gone first, and is what fell out on Hell's Revenge. Then the rest of the bushing seemed to start coming apart inside, too. The other side seems to be fine, so hopefully I just got a bad bushing. IDK.
The only way I know to grease them is to pull them out and lube them inside and out, then reassemble.

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greiswig

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While my truck was in for the fuel filter recall, I asked the tech to look at this issue for me. It had been several hundred miles since I cleared the code, so I expected that it was waiting there in pending status, as it has been doing for awhile. Interestingly, he didn’t see anything using his two scan methods.

I‘ll keep an eye on it, but…I guess I’ll count myself lucky for now.
 

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