Been awhile since I had fuel trim issues but from what I remember your long term value shouldn't be that high

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No, those fuel trims are high. My '97 sits around zero. Do the trim numbers get better when you accelerate?

 

should it be around 0 even when i’m driving? i’ll take it for a spin later and let you know what it find

 

Yes, fuel trims should fluctuate around zero. Vacuum leaks are a common cause of high trims at idle but correct themselves under load.

 

Trims can and will fluctuate all the time, Sure they should be zero in their most optimal situation but if you're pumping Gas with 10% ethanol they will never be zero, manufacturers have baked a new stoich ratio in some vehicles to account for the E10 stuff. 10-11% is a little high at idle but not bad, they can go + or - 25% max, past that range you get a too lean or too reach codes. are they settling down closer to zero when you're driving around ?

 

Sure they should be zero in their most optimal situation but if you're pumping Gas with 10% ethanol they will never be zero,

Rsmrangler, can you clarify? This statement belies experience. I've verified fuel trims on various vehicles, and most have settled around a LTFT of zero or slightly above (under 5%). I currently run 10% ethanol gasoline in my Wrangler, RX350, and Land Cruiser. With the exception of the Lexus, LTFT remains steady around zero. Lexus is currently somewhere between 4 and 7. I've observed no noticeable difference in trims moving from an area where we had access to non-ethanol gasoline to an area that doesn't.

In addition, it would seem strange that later model vehicles, whose engineers anticipate heavier use of ethanol blends, would exhibit higher trims using e10, but old TJs and Land Cruisers wouldn't.

 

this is at 2.5k rpms

 

this is at 2.5k rpms

Have you tried cleaning your MAF sensor and throttle body yet?

 

Nice. With your fuel trim numbers and cleaned throttle body and MAP, I'd rule out a vacuum leak next.

Regarding O2 sensors, what kind of numbers are you getting on them?

 

Nice. With your fuel trim numbers and cleaned throttle body and MAP, I'd rule out a vacuum leak next.

Regarding O2 sensors, what kind of numbers are you getting on them?

i don’t think i’m able to pull o2 sensor data on jscan? how would i check for a vacuum leak? would i just use a smoke machine on the vacuum line where the brake booster goes? how many vacuum lines are there?

 

 

You may have to change the MAP. I didn't know this:

"On engines that use a manifold absolute pressure (MAP) sensor to determine airflow, a vacuum leak does not affect fuel trim because the extra air (pressure) in the manifold is still measured by the MAP sensor."

I hope we can get someone with experience in diagnosing fuel trim anomalies on MAP systems.

 

So that rules out a vacuum leak, I kind of figured it wasn't that. So no possibility of it being the o2 sensors? it does have 135k miles. Is there anyway of cleaning them out if anything? I don't mind replacing them if I have to but it'd have to wait until after the holidays unfortunately.

 

Your O2 sensors appear to fluctuate, so that's good.

 

I use an oscilloscope to check O2 sensors. The data changes so fast you can possibly see it with a meter or a scanner, unless it makes a graph.

Here is a good and bad O2 sensor.

Al in Tucson Somehow I posted this as I was trying to add the picture.

 

Your O2 sensors appear to fluctuate as expected between minimum and maximum (at least on bank 1). Usually, one goes out. When this happens only that bank's trim numbers will change. Your elevated numbers occur on both banks, indicating something else.

 

geez this is turning into a bigger headache than I thought, I mean how many more things could it possibly be? fuel pump issue?
Edit: at wide open throttle long term and short term all go to 0. would a faulty fuel pump/ injector even let this happen? I have plenty of power too.

 

To illustrate: when the downstream O2 sensor of my Land Cruiser failed, it was reading between 0.01 and 0.20 and averaged 0.04 on a two hour trip. All of the other O2 sensors fluctuated freely between 0.10 and 0.90. Under these conditions, only bank 1 fuel trims were affected; and even then, they never reached double digits.

 

yeah that's why im so confused. the main issue is during idle and low rpms. because at wot they all go to 0. and anything above 2k arms is about 4-8 which is acceptable from what ive seen.

 

I was thinking fuel delivery issues as well. I was hoping someone with Wrangler specific fuel trim experience would be able to help.

 

time to hemi swap the damn thing and forget about fuel milage completely. I wish lol

 

Have you tried a fuel system cleaner like Techron? If you see a regression to the mean, you'll know it's a fuel delivery problem.

 

Yes I have tried it and no difference

 

Damn, I think you've tapped my knowledge base.

 

No worries. you helped a lot more than I expected to get from anyone online. Appreciate your time and help very much. I’ll upload any progress if there is any.

 

Thank you

I'd like to know about the successful diagnosis and remedy, especially if the fuel trim numbers are indicative of the problem.

 

Also from the OP jscan print screens while the LTFT's are showing 10% the STFT's are 0 or negative. He has also stated the Jeep is running good without any issues. OP you can do a simple thing for now, reset your battery. Just disconnect the + terminal for say 30 min or so. What we're looking is to reset your fuel trims so next time you start the Jeep they're at 0% and they'll start learning again. Also to keep in mind your o2 sensors have 135k miles so they're not exactly new. they're a key component that make your fuel trims. You can monitor their voltage but without a way to see that voltage in a diagram to see how fast or slow they cycle up and down i don't know if you can make a determination of whether or not they're tired already or not.

 

i’ll disconnect the battery and see what happens. i got a different app that let’s me monitor the voltage. i’ll upload some pictures after i disconnect the battery for 30 minutes. like you said, i think i’ll but the bullet and get some o2 sensors to see if that helps.

 

I would try a new map sensor. Or borrow a friend's sensor and see what happens. The data shows whatever it is isn't isolated to one cylinder or bank. More of a centralized issue.

 

called a couple dealerships and one not too far from me has 2 in stock. ill pop it in first chance I get and report back.

 

got these from my uncles 2011 wrangler at idle as well. 101k miles. gets better gas mileage than me with 35’s and 3.21 gears in a 4 Door

 

Update: I got a new MAP sensor from the dealership yesterday, but unfortunately same results as before.

 

You have confirmed the trims may be a little more normal for your year model though on both vehicles used for the test have over 100k miles and the o2 snesors tend to react slower with miles and you may see some drifting towards the lean side.

Confirm your fuel trims after doing the battery reset and take a look at both stft and ltfts. You didn't have to change the MAP unless you were getting a MAP DTC.
You may just need basic tune up stuff, new plugs, new wires, new o2 sensors, new air filter, do an injector cleaning, etc.
Also going from MT to AT makes a nice difference.

 

You have confirmed the trims may be a little more normal for your year model though on both vehicles used for the test have over 100k miles and the o2 snesors tend to react slower with miles and you may see some drifting towards the lean side.

Confirm your fuel trims after doing the battery reset and take a look at both stft and ltfts. You didn't have to change the MAP unless you were getting a MAP DTC.
You may just need basic tune up stuff, new plugs, new wires, new o2 sensors, new air filter, do an injector cleaning, etc.
Also going from MT to AT makes a nice difference.

new plugs, wires, filter, pcv valve,full synthetic oil and mopar filter about 1k miles ago so i guess only thing left is o2 sensors.

 

I might have missed it but what kind of decline have you seen in your mileage?

 

I’ve been getting 9-10.8 MPG on a stock 2 door with 3.73 gears

 

Yeah that is not good, especially with no other changes. Just asking because I have seen people on here put different size tires on their rig and lose some MPG's and not take into account the different tire sizes. The fact you know what fuel trims are tells me your not in the same boat. I was just curious if you were talking going from 20 -18 or something more drastic, I would say 9-10 is more drastic.......I lose about 2 mpg's each winter with our winter blend fuel.

 

yeah i see it all the time where people expect miracles from their rigs but i just can’t find a reason why i’m getting 9-10mpg

 

Can you get EGR valve information on your engine monitoring app? It seems that a bad EGR valve can cause your symptoms.

 

i checked my EGR commanded and EGR error and they stayed at 0 until about over 1.5k RPMS which is when my fuel trims start to get closer to 0, after 1.5k rpm’s the egr commanded ranges from about 35-69 with an ever age of about 45 and the egr error will be all over the place from -3 to even 99 with an ever age of about 30 or so.