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Cruise Control Surging(or something...)

3085 Views 4 Replies 4 Participants Last post by  roger.trcranch
When I'm running using cruise control, it'll be cruising along just fine, and then the engine will randomly surge up about 250 rpms and bounce back down to where it should be. It will sometimes cruise for a few minutes steadily, and then it'll do it. It's very sporadic, but definitely does it every time I put it in cruise.

Also, it did do this twice over last weekends journey when I wasn't cruising, just driving along at 70 with my foot on the gas and it would do it. Once I gunned it to pass someone, it was fine for the remainder of the trip.

I'm mostly concerned with the cruise issue, has anyone experienced this before?
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Is the vehicle maintaining the same speed, or does it speed up and slow down? Are you running larger than factory tires on stock gears?

My first thought: I don't think this is a cruise issue, I think it is your tranny coming in and out of full lock (torque converter). This will be exagerated with large tires and stock gears, on hills, or driving into the wind. By the way, my ZJ did this for 3 years and 35k. I was running 32's with 3.73's. It really only happenend with a slight load at high speed (hill or towing). The Jeep was just working a little hard and didn't know if it could lock up in overdrive, or just stay in high gear.
It's pretty much maintaining the same speed, I can feel it jump a tad bit, but my passenger didn't even notice. I'm running 30x9.50 tires, and it did this on stock tires as well(although these aren't much bigger anyways).

It was definitely windy, and there would be some random hills or slight inclines, but nothing serious. If I remember correctly, it did this even when it wasn't windy though.

My first thought was maybe the TPS? I'm hoping it's not a torque converter problem...

Thank you for your input.
I had the exact same symptoms with my 2001 4.7 gc. The dealer could not figure out the problem. Turned out to be the TPS . I replaced the tps after starting to have problems with a high idle rpm at startup. After replacing the tps for the idle problem, my cruise control started to work properly again. I suspect because the cruise control causes fairly abrupt throttle response this will accentuate any small noise signal problem with the tps before the tps goes totally bad. and perhaps cause torque convertor to lock/unlock intermittantly when in cruise control. Bottom line - get a new tps, they are cheap.
My '23 Grand Cherokee surges the entire time it's in cruise, both modes when there is nothing in front of it to impede the set speed. Just a minor speed up/slow down but constantly like it's trying too hard to maintain the exact set point. Most have a little tolerance for coast and droop before you get a correction. This thing stays right on the button and the constant surge is annoying. I hope there is an update coming.
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