Bank 2 Negative Fuel Trims

[redsyphon]

I noticed a power surging in my 2018 JLUR last week as I was on my way to take her in to my mechanic to replace a few coolant hoses.

I pulled codes and got a fault on one of the O2 Sensors. That was replaced and I haven't had any surging of power at 50-60mph since.

However, watching the fuel trims i noticed that Bank 2 has a consistent -7 to -9% long term fuel trims when at idle. When at low speeds, Bank 2 jumps to 4 to 8% positive trim, and at 45mph and above both banks more or less equal out.

Bank 1 stays pretty consistent between -4 to 4% at any given time.

If I put the skinny pedal on the floor, then she runs fine but I do get a slight oil/gas mixture smell. Almost like the PCV is bad, but it quickly goes away. Note: I checked for a bad PCV

Question: Is this normal behavior for Bank 2?
I'm trying to determine if I might need to plan for injectors and/or if i have something else weird going on like a exhaust leak, etc.

The engine did have a bad head gasket and was pulled apart October of last year. The block.was machined and gasked replaced, etc. Has ran fine since then...

Roughly 90k miles on it.

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[bmpcamry09]

Check valve cover gasket for small leak that drips down into the O2 sensor and skews readings.

Also, what brand O2 sensor did they go in with? NTK/NGK or factory Mopar are the only brands I trust on these. Anything else could be skewing data.

 

[redsyphon]

It was an OEM O2 Sensors, but I'll check to see if there's anything from the valve cover gasket.

 

[redsyphon]

Went and put eyes on all four O2 Sensors after a few drives and all are bone dry.

I wasn't able to find any leaks on the engine, save for some dark drips on two of the coolant lines going to the trans oil cooler.

I hosed those off with break clean and will see if anything comes back. But I wouldn't think that would cause the negative trims on bank 2.

 

[bmpcamry09]

Went and put eyes on all four O2 Sensors after a few drives and all are bone dry.

I wasn't able to find any leaks on the engine, save for some dark drips on two of the coolant lines going to the oik cooler.

I hosed those off with break clean and will see if anything comes back. But I wouldn't think that would cause the negative trims on bank 2.

Only other thing that causes negative trims if the sensors are actually reading correctly is usually fuel delivery related like a hanging injector or the like. In extreme cases a cylinder with low compression ca. cause it too. But Maybe throw a bottle of Techron in with the next fill up.

 

[redsyphon]

Only other thing that causes negative trims if the sensors are actually reading correctly is usually fuel delivery related like a hanging injector or the like. In extreme cases a cylinder with low compression ca. cause it too. But Maybe throw a bottle of Techron in with the next fill up.

Techron is in there and I have another bottle for the next tank as well. Did that last week

It may be the injectors. I was thinking about getting them replaced with quality units. But I wanted to get other opinions before starting down any parts cannon efforts

 

[alphawolff]

Is 10% to -10% fuel trim even an issue? Pretty sure this is quite literally working as designed. Not all components wear evenly, and fuel trim adjustment on the fly is the entire point of O2s other than cat monitoring. If you were hitting 20% thresholds you'd have an issue

 

[redsyphon]

Is 10% to -10% fuel trim even an issue? Pretty sure this is quite literally working as designed. Not all components wear evenly, and fuel trim adjustment on the fly is the entire point of O2s other than cat monitoring. If you were hitting 20% thresholds you'd have an issue

That's what I was wondering. I'd always grown up with the 5% difference rule between banks, so when I saw bank 1 at -4% and bank 2 at +7%, that seemed like a possible issue. But, that's "old" knowledge, so I wasn't sure...

The surging issue hasn't come back and she's not throwing any money lights, so I don't want to go looking for a problem to fit a solution of it's not needed.

 

[alphawolff]

That's what I was wondering. I'd always grown up with the 5% difference rule between banks, so when I saw bank 1 at -4% and bank 2 at +7%, that seemed like a possible issue. But, that's "old" knowledge, so I wasn't sure...

The surging issue hasn't come back and she's not throwing any money lights, so I don't want to go looking for a problem to fit a solution of it's not needed.

It's not a 11% difference between banks really. It's one bank reducing fuel by 4% from standard and the other adding 7% from standard. Best to think of it as two separate 3 cylinders in that sense. In a lot of high performance engines V6s/V8s tend to have completely identical and dual air injection/ignition systems. The 2.9L QV engine from alfa has dual everything for example. Two throttle bodies, high pressure pumps. Hell, it even has 2 PCMs, one for each bank. It's just two engines that happen to be driving the same crankshaft

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