Well, now that I've read every RENIX thread I could find that seemed to be relevant to the issues I have with my truck, I figured I'd make one for myself. Somehow I almost feel like it's some sort of rite of passage for new Jeep owners.
Anyway, after going on a sensor testing, replacing, and testing again binge, I have improved the overall drivability of my XJ, and have narrowed the symptoms of my RENIX problems down to a (thankfully) much shorter list. They are:
*Random high idle. The truck idles perfectly at about 700rpm when it's in it's cold start cycle. Most of the time, the truck will idle at 900-1100 when warm in drive with my foot on the brake, and at 1200-1600 in park/neutral. Sometimes it idles at 1000-1100 in park/neutral when warm. I haven't been able to pin down any pattern to this at all. The idle speeds are stable, there's no hunting at all. The only other thing I noticed that may be related is that the egnine speed jumps to 2500-3000rpm immediately after starting the truck, before it settles down to whatever idle speed it desires at the time.
*HORRENDOUS fuel economy. I'm talking 10-11mpg consistently. The best I've seen is 14mpg, and that was an all-highway trip. The truck has a 2" BB and 30" BFG ATs. Otherwise the drivetrain is stock. I have a heavy foot, but it's not heavy enough that I get what seems to be about half the MPG that most people seem to be getting from XJs similar to mine.
*Backfiring/loss of power. I could help this a bit if the truck didn't insist on shifting into 4th gear and overdrive as soon as possible, but I suppose that's the woe of owning a vehicle with an automatic(my first, and likely my last). Anyway, if I accelerate away from a stop(say from a traffic light), then let off of the gas completely(to avoid running into the person in front of me who can't operate the skinny pedal properly), when I get back on the gas again, the truck backfires, hesitates, and then accelerates normally. This is worse when it's cold, but also happens when it's warm. It also happens at highway speeds when I do the same thing(throttle, release, throttle again).
Aside for these issues, the truck runs very well. It has plenty of power, responds well to throttle inputs at all speeds(short the backfiring thing), and upshifts/downshifts as well as I can reasonably expect from a 19-year-old truck.
Any thoughts you guys have on this would be greatly appreciated. I love driving this thing, but I need to rectify these issues so I can trust it 100%, as it becomes my daily driver in a few months when the lease on my other car ends.:worship:
Anyway, after going on a sensor testing, replacing, and testing again binge, I have improved the overall drivability of my XJ, and have narrowed the symptoms of my RENIX problems down to a (thankfully) much shorter list. They are:
*Random high idle. The truck idles perfectly at about 700rpm when it's in it's cold start cycle. Most of the time, the truck will idle at 900-1100 when warm in drive with my foot on the brake, and at 1200-1600 in park/neutral. Sometimes it idles at 1000-1100 in park/neutral when warm. I haven't been able to pin down any pattern to this at all. The idle speeds are stable, there's no hunting at all. The only other thing I noticed that may be related is that the egnine speed jumps to 2500-3000rpm immediately after starting the truck, before it settles down to whatever idle speed it desires at the time.
*HORRENDOUS fuel economy. I'm talking 10-11mpg consistently. The best I've seen is 14mpg, and that was an all-highway trip. The truck has a 2" BB and 30" BFG ATs. Otherwise the drivetrain is stock. I have a heavy foot, but it's not heavy enough that I get what seems to be about half the MPG that most people seem to be getting from XJs similar to mine.
*Backfiring/loss of power. I could help this a bit if the truck didn't insist on shifting into 4th gear and overdrive as soon as possible, but I suppose that's the woe of owning a vehicle with an automatic(my first, and likely my last). Anyway, if I accelerate away from a stop(say from a traffic light), then let off of the gas completely(to avoid running into the person in front of me who can't operate the skinny pedal properly), when I get back on the gas again, the truck backfires, hesitates, and then accelerates normally. This is worse when it's cold, but also happens when it's warm. It also happens at highway speeds when I do the same thing(throttle, release, throttle again).
Aside for these issues, the truck runs very well. It has plenty of power, responds well to throttle inputs at all speeds(short the backfiring thing), and upshifts/downshifts as well as I can reasonably expect from a 19-year-old truck.
Any thoughts you guys have on this would be greatly appreciated. I love driving this thing, but I need to rectify these issues so I can trust it 100%, as it becomes my daily driver in a few months when the lease on my other car ends.:worship: