weirdest thing? i was trying to blast through some mud the other day, and for some reason i couldnt get over 2000rpms. this was in 4wd. on the highway it revs fine through all the gears. i had to pull a buddy out of the mud and my jeep was spinning the tires but still wouldnt rev past 2000 rpms. what gives? it doesnt feel like the engine is bogging. its a very strong running jeep. its a 97 grand, 4.0 inline 6, auto

 

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Weird indeed.. Your jeep's engine doesn't know if it's driving thru mud, grass or lunar dust it just runs.
*You say it did it in 4wd (in mud) but shifted/revved up fine on the hiway? What if you put it in 4wd on the hiway? Does it still run fine? I mean over 2,000 rpm? I don't know what being in 4wd would change as far as engine rpm.
*Probably end up being a dirty sensor or something..
I wanna see what you figure out

 

i have read that the xj has a limp home mode that wont let the engine rev over 2000 rpm to prevent further damage maybe kicking it into 4wd is accendently tripping it some how