JK traction control issue

#1
Looking for your ideas re: a long-term gremlin I’ve been trying to fix. My ‘07 JK’s traction control kicks in at 25 mph, but only when making left turns while going down hill through one particular canyon. I’ve driven this canyon road since the Jeep was new, and as the modifications and evolution took place, the Jeep has never been close to being out of control or leaning much. For many years, this issue would only occur on one 180*, 20-mph turn, but after the road was repaved a few years ago, it happens on each and every left turn.

A couple of months ago, I started to try to figure things out. As a result, I now have new ball joints, u-joints, lower control arms (front and rear); new bushings for the upper controls arms (front and rear) and the Currie Antirock rear swaybar; and new front speed sensors and rear ABS/speed sensors.

As the Jeep is nearly 14 years old and has 179,000 miles on the clock, these things needed some TLC, so I don’t necessarily mind that what I’ve done has not fixed the issue. If there’s something else anyone can suggest I try, I’m all ears, even if it’s just to live with my “Grimes Canyon gremlin.”
 

woody

Adventurist
#2
Looking for your ideas re: a long-term gremlin I’ve been trying to fix. My ‘07 JK’s traction control kicks in at 25 mph, but only when making left turns while going down hill through one particular canyon. I’ve driven this canyon road since the Jeep was new, and as the modifications and evolution took place, the Jeep has never been close to being out of control or leaning much. For many years, this issue would only occur on one 180*, 20-mph turn, but after the road was repaved a few years ago, it happens on each and every left turn.

A couple of months ago, I started to try to figure things out. As a result, I now have new ball joints, u-joints, lower control arms (front and rear); new bushings for the upper controls arms (front and rear) and the Currie Antirock rear swaybar; and new front speed sensors and rear ABS/speed sensors.

As the Jeep is nearly 14 years old and has 179,000 miles on the clock, these things needed some TLC, so I don’t necessarily mind that what I’ve done has not fixed the issue. If there’s something else anyone can suggest I try, I’m all ears, even if it’s just to live with my “Grimes Canyon gremlin.”
Don't know if this helps any but in the Toyota world there is a method to recalibrate the VSC?
 
#3
Back when the dealership used the StarScan tool, my mechanic was able to adjust the sensitivity. At some point in its life, however, the computer was reflashed and the dealership now uses the Wytech tool, which can’t get down into the level of adjustment.
 
#8
I don't think its a suspension issue. I am not a jeep guy, but I would be looking at yaw type sensors?
No associated codes have been thrown by the dynamic sensor and it appeared to my mechanic to be operating properly when he was hooked up to the obd2 on a test drive. Earlier this week, I pulled the console and it appeared undamaged, clean, and secured properly. With a new one somewhere north of $400 and no direct evidence of it being the issue, I’m reluctant to replace it just yet. Instead, I’m going to see if the dealership can reflash the computer, and if that doesn’t change anything, perhaps see if someone local with an ‘07 (maybe an ‘08?) would be willing to let me plug theirs into my Jeep and see if there’s a difference. The next step after that might be tracing the sensor’s wiring for signs of damage.

I’m working nearly every night through the month of December, so I won’t be able to follow up with Rebel Offroad until the new year.
 
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#9
Update: Today I swapped wheels and tires with a friend for a test run through the canyon. The tires were 255/70R18 Bridgestone Dueler A/Ts, vs. my 35x12.50R17 BFG KO2s. The borrowed tires were run at 35 psi (I’ve run my KO2s at 35, 45, and 50, with the 35s too soft and the others good) and in two runs through the canyon, the Duelers resulted in only one activation of the traction control, and that happened when I intentionally pushed it a bit.

So, based on this non-scientific test, it appears the problem might lie with my tires. This seems strange to me, though, as my first set of KO2s did not cause this problem and these are less than 6 months old.

Anyone have any thoughts?
 
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Greg

Adventurist
Senior Staff
#10
Update: Today I swapped wheels and tires with a friend for a test run through the canyon. The tires were 255/70R18 Bridgestone Dueler A/Ts, vs. my 35x12.50R17 BFG KO2s. The borrowed tires were run at 35 psi (I’ve run my KO2s at 35, 45, and 50, with the 35s too soft and the others good) and in two runs through the canyon, the Duelers resulted in only one activation of the traction control, and that happened when I intentionally pushed it a bit.

So, based on this non-scientific test, it appears the problem might lie with my tires. This seems strange to me, though, as my first set of KO2s did not cause this problem and these are less than 6 months old.

Anyone have any thoughts?
Reprogram the tire size?

https://jksmfg.com/c-1132627-shop-by-jeep-wrangler-jk-2007-2018-programmersjeep-wranglerjk.html
 

Greg

Adventurist
Senior Staff
#12
Thanks, but the AEV Procal has already taken care of that. I’ve got rebuild kits for my front and rear track bars arriving soon and ordered up some new wheels so I will ditch the spacers I’ve had for many years.
Maybe that's the failing component? Was it removed when the 32s were put on? Has it's calibration drifted over time? Did someone accidently reset it?

I'm thinking this. You have a 180 deg turn where all tires are tracking at different radius from the center point of the turn. You decreased the radius and circumference of the tires increasing their rotation speed and the problem goes away. That the faster rotating tires means that the difference of the rotational speeds between each tire and the average rotational speed of all tires isn't significant enough to trigger traction control. As you increase the radius of the tire the average rotational speed of all tires in the turn drops. However they are still basically tracking the same path the and the difference of the rotational speeds between each tire remains about the same. When compared against the slower average rotational speed it's enough to trigger traction control.

Or perhaps it's enough when combined with something else like sensor and wire corrosion.
 
#13
Maybe that's the failing component? Was it removed when the 32s were put on? Has it's calibration drifted over time? Did someone accidently reset it?

I'm thinking this. You have a 180 deg turn where all tires are tracking at different radius from the center point of the turn. You decreased the radius and circumference of the tires increasing their rotation speed and the problem goes away. That the faster rotating tires means that the difference of the rotational speeds between each tire and the average rotational speed of all tires isn't significant enough to trigger traction control. As you increase the radius of the tire the average rotational speed of all tires in the turn drops. However they are still basically tracking the same path the and the difference of the rotational speeds between each tire remains about the same. When compared against the slower average rotational speed it's enough to trigger traction control.

Or perhaps it's enough when combined with something else like sensor and wire corrosion.
You know, we didn’t recalibrate with the Procal with the borrowed wheels/tires.:oops:
 
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