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Discussion Starter #1
This is a recent development.

2012 JKUR. Stock Engine. 72,000. All service intervals meticulously met.

Recently replaced all four axle shafts and added a front BBK. Wheel speed sensors replaced about 2 months ago.

Jeep ran fine for the last two weeks after axle shaft replacement. Oil changed two weeks ago and new tank of fuel last weekend.

Now the engine is lugging at about 60mph. Rpms are not surging. Just feels like the engine lugs. Like a long hiccup in power. For some reason, it also makes the traction control and abs light come on and stay on.

We're at a loss. Any ideas?

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This is a recent development.

2012 JKUR. Stock Engine. 72,000. All service intervals meticulously met.

Recently replaced all four axle shafts and added a front BBK. Wheel speed sensors replaced about 2 months ago.

Jeep ran fine for the last two weeks after axle shaft replacement. Oil changed two weeks ago and new tank of fuel last weekend.

Now the engine is lugging at about 60mph. Rpms are not surging. Just feels like the engine lugs. Like a long hiccup in power. For some reason, it also makes the traction control and abs light come on and stay on.

We're at a loss. Any ideas?
Sounds to me like it might be kicking into 'Limp Mode.' When it does this, what do you do about it? I drove mine around in limp mode for a very short while. It is about 1/10 the power of normal mode. I could accelerate up to 55 or 60 mph, but it took 2-3 miles to get up there. VERY obvious what it is way lacking in power. I had to pull to the shoulder, turn the key off for several minutes and then restart it to get it OUT of Limp Mode.

Is yours kicking into Limp Mode? I am making an assumption on this, but since you didn't mention it, the check engine light not coming on is a good thing!! No error codes?

What brand wheel speed sensors did you put in when you replaced your old ones? Did you keep your old one? Have you tried to put your old ones back on and see if that fixes the problem? The rears are quite easy but the front's aren't so easy. That being the cheapest thing to do, I would try that next.
 

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when you get home, check to see if any rims feel hotter then the others. you could have a seized brake caliper which is over heating the wheel speed sensor/abs sensor.
 

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There are lots of things that throw the motor into safe mode... mine was doing it because of a bad 4-wheel drive mode sensor... they replaced the transmission controller but I have a feeling it was the sensor in the shifter itself...
 

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Discussion Starter #8
There are lots of things that throw the motor into safe mode... mine was doing it because of a bad 4-wheel drive mode sensor... they replaced the transmission controller but I have a feeling it was the sensor in the shifter itself...
It's definitely not going into a safe mode. I've experienced that before. This isn't it.

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i'm getting ready to deal with a dragging rear caliper.
depending on severity they can be hard to notice.
in my case the jeep just doesn't seem to roll as free,the tranny shifts a bit spikey
gas use is up slightly and at know cruising speeds it seems to be running a few rps higher.
I started shooting rotor temps and noticed a rear rotor running consistently 50F hotter then the rest.
just something to consider ..
 
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Discussion Starter #10
i'm getting ready to deal with a dragging rear caliper.
depending on severity they can be hard to notice.
in my case the jeep just doesn't seem to roll as free,the tranny shifts a bit spikey
gas use is up slightly and at know cruising speeds it seems to be running a few rps higher.
I started shooting rotor temps and noticed a rear rotor running consistently 50F hotter then the rest.
just something to consider ..
That could explain the lights but the engine is definitely losing power momentarily which I'm sure isn't caused by the brakes. I'll be checking the brakes.

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its a long different story ...but no lights or codes ,that includes ABS system codes
this is a second brake caliper i'm dealing with.
when my first seized up and I literally smoked the pads it took a long time till I got a ABS lite.

this time the only reason I noticed was the engine performance seemed just a bit off.
sometimes it is a bit worse then others just driving block to block.

unlike a front caliper that will result in a steering pull ,a dragging rear acts more like a parachute
 

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Discussion Starter #12
Well, I think I got it. I went back through all the things I've recently done and checked them off. When I got to the rear, drivers side speed sensor, I discovered that the retention clip was broken. The the connection wasn't tight and so it was wiggling loose. I went to O'Reilly's and got a new plug/wire for $19.99. Added some waterproof wire connectors and did the job. A good test drive later and none of the problems resurfaced. So far, so good. I don't usually get this lucky with a repair. We'll see.

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This is a recent development.

2012 JKUR. Stock Engine. 72,000. All service intervals meticulously met.

Recently replaced all four axle shafts and added a front BBK. Wheel speed sensors replaced about 2 months ago.

Jeep ran fine for the last two weeks after axle shaft replacement. Oil changed two weeks ago and new tank of fuel last weekend.

Now the engine is lugging at about 60mph. Rpms are not surging. Just feels like the engine lugs. Like a long hiccup in power. For some reason, it also makes the traction control and abs light come on and stay on.

We're at a loss. Any ideas?
Glad you possibly hit the nail on the head and nailed the problem. One quick question just for future possible help on the forum. WHY did you change the wheel speed sensors in the first place and did you put OEM or aftermarket replacements on?
 

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Discussion Starter #14
Glad you possibly hit the nail on the head and nailed the problem. One quick question just for future possible help on the forum. WHY did you change the wheel speed sensors in the first place and did you put OEM or aftermarket replacements on?
I replaced them because it was a home mechanic process of elimination. The traction control light would intermittently come on and would only go off if you cycled the engine. Nothing else was affected. Replacing all 4 was pretty cheap and easy. It also solved the problem, until we bent the rear axle shafts. It must have been when i replaced the axle shafts that the electrical connector retention clip broke. I replaced the original sensors with whatever O'Reilly auto parts sold me. Days later and the problem is still solved so that's a win.

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I replaced them because it was a home mechanic process of elimination. The traction control light would intermittently come on and would only go off if you cycled the engine. Nothing else was affected. Replacing all 4 was pretty cheap and easy. It also solved the problem, until we bent the rear axle shafts. It must have been when i replaced the axle shafts that the electrical connector retention clip broke. I replaced the original sensors with whatever O'Reilly auto parts sold me. Days later and the problem is still solved so that's a win.
Ooooh. I pulled my RR sensor out to clean the iron filings off of it. When I put it back in place, I noticed that the gap on the RR was MUCH wider than the gap on the LR one. When putting the wire back on, I also broke the retention clip. Guess I'll be ordering new wires for the rear also. Thanks for the heads up. I was going to see if I could get away with running it with that broken clip.

Hey, us 'Home Mechanics' have to do anything possible to keep from taking our heeps back to the STEALERSHIP for minor things. Even if the ARE still under warranty.
 

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I wish I could just buy the retention clips, my rears are both broken. I push the plug together tight and tape the crap out of it.
 

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Discussion Starter #17
I wish I could just buy the retention clips, my rears are both broken. I push the plug together tight and tape the crap out of it.
The wires were $19.99 at o'Reilly's and easy enough to do.

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I had the same issue with my 2012. Turns out I had had a small fray in the wire that comes from the speed sensor and runs across the top of the frame. It was actually ‘burnt’. Dealer doesn’t know how it happened but they spliced in a new section and all has been fine.
 
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