1. 1999 XJ
2. 4.0
3. Auto
4. Need to go check transfer case. Don't think it is applicable.
First time post, go easy on me. ;-)
Got an XJ a couple months ago because my buddy had one in high school - so I always wanted one - and I need a rig to take my kids out and go hiking, camping, hunting, etc.
I have done a few things:
- New fuel pump (Delphi)
- Fan shroud and 3 10" fans
- Added Transmission cooler
- Replaced the camshaft sensor (after error code)
- Replaced the crankshaft position sensor
I have taken it on a few trips to the mountains in CO for camping. The first one I discovered the 2 9" fans the previous owner had installed don't cut it in 4 low. So I added the shroud with 3 10" fans and the transmission cooler. No problems there now!
On the way back from that trip and few short trips, I noticed some surging/tripping/stumbling when on the freeway. It was hot, so I didn't think much of it. Also had some hard times starting the vehicle warm. Between it all, I thought it could be the fuel pump, so I replaced it. I was happy I did because it seemed like I got 20 years worth of fuel debris out of there! (Nothing too crazy.)
I also noticed going up hills the cabin vent fans (no AC on this rig yet) some times would halt. Maybe it wasn't the fan, maybe it was a vent behind them would close. This reminded me of my dad's 1950 pickup that had the wipers run off vacuum lines and would pause when the truck was working hard....
Then I replaced the crankshaft position sensor, because I heard that was probably the source of the hard starts (cranking it a couple times to get it to sometimes start when the engine was hot). That seemed to have fix that.
PROBLEM:
But on the last couple trips, around town or from mountains (on 85-90 degree days), the tachometer has been surging 500-750 RPMs when cruising on the freeway or at stoplights. It has totally died twice (both times in parking locations). Before it dies it seems like it looses it's power and sounds like it is "choking."
Currently, it only has a cat - no muffler or tail pipe. Both oxygen sensors are in place. There is no check engine light. Clean oil (less than 1500 miles).
QUESTION:
Why does it keep wanting to die? What could be causing the RPMs to surge? What should I look at next?
THOUGHTS:
- Check for vacuum leaks
- Replace MAP sensor
- Replace throttle position sensor
- Check spark plugs (pulled one, normal wear)
- Plug cables seem fine
- Should I use Seafoam Spray? (since I don't know the full history of the vehicle)
PREVIOUS IDEAS:
- O2 sensors throwing off fuel mixture. Heard this would probably throw a code. But not having any tail pipe still has a bit of a question in my head.
I am sure I am forgetting something.... Feel free to ask and I would really appreciate any suggestions. I don't mind replacing things but I'd like to know - not shotgun guesses.
What should I try next?
Thanks!
2. 4.0
3. Auto
4. Need to go check transfer case. Don't think it is applicable.
First time post, go easy on me. ;-)
Got an XJ a couple months ago because my buddy had one in high school - so I always wanted one - and I need a rig to take my kids out and go hiking, camping, hunting, etc.
I have done a few things:
- New fuel pump (Delphi)
- Fan shroud and 3 10" fans
- Added Transmission cooler
- Replaced the camshaft sensor (after error code)
- Replaced the crankshaft position sensor
I have taken it on a few trips to the mountains in CO for camping. The first one I discovered the 2 9" fans the previous owner had installed don't cut it in 4 low. So I added the shroud with 3 10" fans and the transmission cooler. No problems there now!
On the way back from that trip and few short trips, I noticed some surging/tripping/stumbling when on the freeway. It was hot, so I didn't think much of it. Also had some hard times starting the vehicle warm. Between it all, I thought it could be the fuel pump, so I replaced it. I was happy I did because it seemed like I got 20 years worth of fuel debris out of there! (Nothing too crazy.)
I also noticed going up hills the cabin vent fans (no AC on this rig yet) some times would halt. Maybe it wasn't the fan, maybe it was a vent behind them would close. This reminded me of my dad's 1950 pickup that had the wipers run off vacuum lines and would pause when the truck was working hard....
Then I replaced the crankshaft position sensor, because I heard that was probably the source of the hard starts (cranking it a couple times to get it to sometimes start when the engine was hot). That seemed to have fix that.
PROBLEM:
But on the last couple trips, around town or from mountains (on 85-90 degree days), the tachometer has been surging 500-750 RPMs when cruising on the freeway or at stoplights. It has totally died twice (both times in parking locations). Before it dies it seems like it looses it's power and sounds like it is "choking."
Currently, it only has a cat - no muffler or tail pipe. Both oxygen sensors are in place. There is no check engine light. Clean oil (less than 1500 miles).
QUESTION:
Why does it keep wanting to die? What could be causing the RPMs to surge? What should I look at next?
THOUGHTS:
- Check for vacuum leaks
- Replace MAP sensor
- Replace throttle position sensor
- Check spark plugs (pulled one, normal wear)
- Plug cables seem fine
- Should I use Seafoam Spray? (since I don't know the full history of the vehicle)
PREVIOUS IDEAS:
- O2 sensors throwing off fuel mixture. Heard this would probably throw a code. But not having any tail pipe still has a bit of a question in my head.
I am sure I am forgetting something.... Feel free to ask and I would really appreciate any suggestions. I don't mind replacing things but I'd like to know - not shotgun guesses.
What should I try next?
Thanks!
