Hello, this is my first time posting here but after browsing several other forums and Google I don't really have anywhere else to turn. I have a 2004 jeep wrangler with the 4.0 and manual trans. Just recently out of nowhere I'm having a major loss of power while driving. The jeep will run flawlessly no issues with idle or anything then after about 20 minutes of driving the engine stumbles and will only idle. If I try to give it gas the rpms will not rise at all, it will run rough and die. I usually have to give it about 2 minutes of sitting and I can crank it up and then it will run perfectly again for about 5 minutes or so and the same thing will happen again. This only started about a month after i replaced the fuel pump with a delphi one, So today I tested the pressure and came back around 50. I have replaced the camshaft sensor and crankshaft sensor as well as cleaned the throttle body. Im really leaning towards a sensor but the fact that it will run perfectly for a while really has me stumped. Any help is appreciated Thank you!
Need help with unique power issue
- Thread starter Dwhitt20
- Start date
Is it throwing any codes? How many miles are on it? When is the last time you replaced the O2 sensors?
SaharaBound
TJ Enthusiast
At first it wasn't throwing any codes but just today I got P0171 and P0174. Jeep is fairly new to me O2 sensors are on my list of possible along with MAP AIC and TPS. Wanted to do a bit more research before I start throwing parts at it. I was convinced it was the camshaft and crankshaft from what I read. Miles are 102k
This sounds like either O2 sensors or clogged cats to me. O2 sensors should be replaced every 80k miles as a general maintenance item.
Make certain to use NGK sensors otherwise you’ll have issues. See this thread:
https://wranglertjforum.com/threads/the-official-jeep-wrangler-tj-oxygen-o2-sensor-thread.4068/
Make certain to use NGK sensors otherwise you’ll have issues. See this thread:
https://wranglertjforum.com/threads/the-official-jeep-wrangler-tj-oxygen-o2-sensor-thread.4068/
Those codes are related to a lean condition, likely the MAP sensor or even more likely the fuel pressure regulator, which is located on the to top of the fuel pump. I would get a fuel pressure gauge and start with fuel pressure check, should be able to rent one from auto parts store.
NTK O2 sensors are fine too, they're the same product sold through different channels. Avoid using Bosch O2 sensors in a Jeep.
Appreciate all the quick replies, got the o2 sensors on order so if it works ill update the thread
So wanted to give yall an update, replaced all the O2 sensors and I'm still having the same issue. The rpms drop to idle and I can't give it any gas at all. Next idea was going to change the the MAP sensor and make sure the cats arnt clogged.
2nd update, went ahead and changed the whole exhaust system, so have brand new cats also did the map sensor and tps. Same issue almost seems like its a little worse as once I get it started again only goes about a 1/4 of a mile before the systems start up again. However this time when it was running rough I was able to spray some carb cleaner through the throttle body and the rpms picked up and sounded good for a few seconds. I already tested the fuel pressure, but I'm thinking after I drive the fuel pressure is dropping off, maybe due to a clogged filter or debris in the fuel tank? Just wanted to check in and see if anyone had any more ideas.
Look at your fuel pump I had one on a Cherokee that was fine until I hit a quarter tank then would do that.. it took a while for me to figure that out, but it solved my problem
What happens if you let the TJ sit & idle from a cold start, does the same thing eventually happen once it warms up or is it only associated with driving?
My line of thinking is that your problem may be associated with closed-loop operation once the engine gets to operating temperature. At that point the engine starts taking input from sensors to manage itself, particularly the O2s & coolant temp sensors.
My line of thinking is that your problem may be associated with closed-loop operation once the engine gets to operating temperature. At that point the engine starts taking input from sensors to manage itself, particularly the O2s & coolant temp sensors.
