There definitely isn't much difference in fuels, but fuel freshness, amount of ethanol added and whatever the companies secret sauce of additives are. If you can lock yourself into one filling station, that's probably how to find your best results as the subtle differences all part of the PCM re-learn process.

 

I might be in a bit of a unique situation here due to my current Jeep configuration, but i need some input.

I'm still running stock 225/75R16 street tires, 3.21 gears, with a 6-speed.

I bought a Flashpack a few weeks ago, updated, and installed the 87 tune with no problems what so ever. The driveability on the highway has been vastly improved, and it certainly gave it some more pep on the skinny pedal. Here is my issue though.........

I'm having a HELL of a time with driving in slow traffic or through my neighborhood. Pretty much anything under about 35mph. When I do, it feels like the gas pedal is a damn ON/OFF switch. It is VERY jerky and feels as if there is no modulation at the end of the pedal. I have been adjusting my driving style as best as I can, but there is only so much I can do. For instance, coming up to a 90 degree corner......I let off the gas to slow down, as soon as the pedal reaches the end of its travel I get a jerk bad enough to snap your head forward. I then slow for the corner, travel through the apex, and then gently put my foot back on the gas to accelerate through the corner. As soon as the gas pedal moves it jerks your head back the other way. It reminds me of a comedic skit where someone is trying to learn how to drive stick for the first time. Once I am up to the speed limit, everything is fine and it runs great. I can somewhat deal with it on the street, but I don't think I could handle it offroad. It is extremely discouraging.

Anyone else having this problem? I'm wondering if it doesn't have to do with the tiny tires and tall gearing Vs. most of you guys having heavier tires and taking more oomph to get them moving. It might just make my rig hyper-sensitive to minor throttle changes. I think I am also going to try a different tune this week (maybe the 91 since everyone is raving about it) and see if anything changes.

 

I have a similar simptom with mine. The main thing with mine though is, that after changing the tire size, the spedo is still off, and I still get ESP in he corners. I had 33" tires with the stock tune and was going 5mph faster than the spedo (checked on GPS) before and now with 33" tires programmed i am 5-7mph slower than the speedo, depending on the speed. If i lower the tire size to 31" the speedo is like 3-5 mph off, but i get the ESP sooner or at slower speeds when cornering.
the other thing i noticed is when you look at the axle ratio scren, under low ratio it says 1.00, and under high ratio it says 2.72, is this correct? i have an auto with 4.10 gears.
I'm not completely impressed with the increased power ( I drove a Turbo 328is BMW before this so maybe thats why) but it does shift and drive a lot smoother. I also did not notice much between the 93 tune with 93 gas and the 87 tune with 87 gas, seemed to be abou the same amount of power to me.

 

See my post #1039. I have 5.13s with 37"s.

 

ESP issue shouldnt have anything to do with the tuner.

 

If the jeep does not know what size tire it has, than the esp thinks the wheels are spinning faster or slower than what they really are triggering the esp. either way, the speedo is WAY off even though i have it set to the proper tire size. what is the point of changing the tire size if it doesn't fix the speedo, what is the purpose of the function then?

 

I have 37's and never reprogrammed anything. Never had an issue. The function is to fix your speed and odometer.

 

You can't go by the "advertised" tire size, you have to physically measure it at the air pressure you plan on running. Plug that in and give it a go. Even at that I had to mess with mine a few times to get the speedo dialed in to what the GPS said. Just takes a little time and you will get it right.

 

Ugh, thats what I was afraid of. I am experiencing EXACTLY what your post was about. For as bad/annoying as it is on the street, I can only imagine the problems it causes when offroad. I've totally lost the ability the feather the throttle at low RPMs.

I'm going to continue to play with it for the next week or so, but I might have to go back to stock as well if I can't figure out a solution.

 

The only time mine did anything like this I re-flashed it to a different octane setting, drove it around the block, and flashed it back and it was fine ever since.
What rpm/gear are you running driving at slow speed through the neighborhood. The little V-6 pulls pretty good under 2K at slow speeds. I've found it pretty easy to drive under those condidtions, the wide rpm range and smooth torque curve means you don't need rpm or lots of shifting.