To the community,
I have used much of the information from this site, and the threads herein to diagnose and fix many problems that I have encountered over the years. I appreciate the sound advice and thorough write-ups that you contribute, and I hope to offer the same as I learn.
The background:
I recently purchased a 1998 LX470 with 300k on the odometer, and it is a stellar rig. No major problems have arisen to this point. I picked up the vehicle for $8,000 from a family member who drove it for a year before returning to Germany as a missionary. He purchased it from a fellow that was the head of the maintenance department at a Benz dealership. Service records indicate that the alternator, starter, timing belt, and water pump were replaced at 220k miles with OEM parts. Regular oil changes and other factory prescribed fluid changes were performed at appropriate intervals. Though the high mileage was initially a concern, I purchased the vehicle with confidence and have not regretted it one bit. My thought is that if something went badly wrong, I could recover much of the cost by selling the off-road components and subsequently, the rest of the vehicle for parts. It is outfitted with an ARB front bumper, a Slee spare swing-out rear bumper, and Slee sliders. it sits upon new 285 BFG A/Ts. Perhaps these items won't recover me a full $8k, but they could offset cost in the event of a catastrophic engine event.
The problem:
After driving for a week or so I noticed that the vehicle would decelerate at highway speeds under normal, steady throttle (50-70mph). The speedometer and tachometer dip temporarily, and after pumping the throttle pedal, the vehicle returns to normal acceleration. It will do this 4-5 times on a 15 mile drive to town. Each fit of deceleration lasts for 10-15 seconds, and occasionally will require a few attempts to remedy. On longer drives, 100-300 miles, the vehicle seems not to have the same problem. The event is at least much less frequent on longer drives. It is as though it works out the kinks in the first 50 miles and behaves properly for the duration of the drive. I have read the TPS and APPS write-ups by NMuzj100 and Davidsob from a while back, and they are quite helpful. I suppose my purpose here is to determine if the way I have described this problem is in line with the need for TPS and/or APPS replacement. I notice that changes in weather may have a slight effect on the problem. On hotter days, I feel it more than on cooler days. I live in central California, in a rural area where the air quality suffers from wildfires and almond harvest, and the temperature can reach 105-109F; for what it's worth. After I bought the rig, I replaced the old battery with a new Interstate battery. Due to the battery having been disconnected, the problem went away for a week until it figured out how to misbehave again. The vehicle is not throwing any codes other than an ABS code that hasn't put any lights on the dash, or revealed any braking symptoms. I cannot recall the code exactly, but I will look it up again this week.
My question:
if you were me, would you replace the TPS and APPS according to these symptoms? Would you replace both, or the cheapest one first? Could an ABS code indicate that there is an ABS deceleration sensor that may be the culprit? Thank you for taking the time to read this.
I have used much of the information from this site, and the threads herein to diagnose and fix many problems that I have encountered over the years. I appreciate the sound advice and thorough write-ups that you contribute, and I hope to offer the same as I learn.
The background:
I recently purchased a 1998 LX470 with 300k on the odometer, and it is a stellar rig. No major problems have arisen to this point. I picked up the vehicle for $8,000 from a family member who drove it for a year before returning to Germany as a missionary. He purchased it from a fellow that was the head of the maintenance department at a Benz dealership. Service records indicate that the alternator, starter, timing belt, and water pump were replaced at 220k miles with OEM parts. Regular oil changes and other factory prescribed fluid changes were performed at appropriate intervals. Though the high mileage was initially a concern, I purchased the vehicle with confidence and have not regretted it one bit. My thought is that if something went badly wrong, I could recover much of the cost by selling the off-road components and subsequently, the rest of the vehicle for parts. It is outfitted with an ARB front bumper, a Slee spare swing-out rear bumper, and Slee sliders. it sits upon new 285 BFG A/Ts. Perhaps these items won't recover me a full $8k, but they could offset cost in the event of a catastrophic engine event.
The problem:
After driving for a week or so I noticed that the vehicle would decelerate at highway speeds under normal, steady throttle (50-70mph). The speedometer and tachometer dip temporarily, and after pumping the throttle pedal, the vehicle returns to normal acceleration. It will do this 4-5 times on a 15 mile drive to town. Each fit of deceleration lasts for 10-15 seconds, and occasionally will require a few attempts to remedy. On longer drives, 100-300 miles, the vehicle seems not to have the same problem. The event is at least much less frequent on longer drives. It is as though it works out the kinks in the first 50 miles and behaves properly for the duration of the drive. I have read the TPS and APPS write-ups by NMuzj100 and Davidsob from a while back, and they are quite helpful. I suppose my purpose here is to determine if the way I have described this problem is in line with the need for TPS and/or APPS replacement. I notice that changes in weather may have a slight effect on the problem. On hotter days, I feel it more than on cooler days. I live in central California, in a rural area where the air quality suffers from wildfires and almond harvest, and the temperature can reach 105-109F; for what it's worth. After I bought the rig, I replaced the old battery with a new Interstate battery. Due to the battery having been disconnected, the problem went away for a week until it figured out how to misbehave again. The vehicle is not throwing any codes other than an ABS code that hasn't put any lights on the dash, or revealed any braking symptoms. I cannot recall the code exactly, but I will look it up again this week.
My question:
if you were me, would you replace the TPS and APPS according to these symptoms? Would you replace both, or the cheapest one first? Could an ABS code indicate that there is an ABS deceleration sensor that may be the culprit? Thank you for taking the time to read this.
