Sluggish Jeep tj

[Prestonhoover52]

I have a 2003 Jeep Wrangler tj and it has been running sluggish for months now I replaced the o2 sensors cleaned the throttle body and the iac it still running sluggish and the rpms bounce up and down when you first start it up after it warms up it gets better. It just has a bad idle when you start it up and my gas mileage and power has tanked. What else should I change.

 

[TheBoogieman]

How old are the plugs?

 

[glowell222]

I have a 2003 Jeep Wrangler tj and it has been running sluggish for months now I replaced the o2 sensors cleaned the throttle body and the iac it still running sluggish and the rpms bounce up and down when you first start it up after it warms up it gets better. It just has a bad idle when you start it up and my gas mileage and power has tanked. What else should I change.

I suggest you start troubleshooting instead of changing a bunch of parts. It's an expensive way to go about the problem.

1st: make sure you have a solid baseline and that all of your regular maintenance items are in good shape and up to date.
2nd: make sure you have no vacuum leaks.
3rd: Ensure you are using NTK/NGK O2 sensors. The reason is that the signaling wire and ground wire is exactly opposite of all other O2 sensors, and this will not work with our TJs. Also, ensure that the wiring between the O2 sensors and the PCM are not broken by doing a trace with a multimeter. This is a common issue and not easy to visually identify.
4th: Check to see that your catalytic converters are not blocked. Another common issue that seems to mirror your symptoms. You will need to access the cats and take a look. Scope type cameras are available from Amazon for about $20 or so.

These are the areas in which I would start.

 

[Prestonhoover52]

I suggest you start troubleshooting instead of changing a bunch of parts. It's an expensive way to go about the problem.

1st: make sure you have a solid baseline and that all of your regular maintenance items are in good shape and up to date.
2nd: make sure you have no vacuum leaks.
3rd: Ensure you are using NTK/NGK O2 sensors. The reason is that the signaling wire and ground wire is exactly opposite of all other O2 sensors, and this will not work with our TJs. Also, ensure that the wiring between the O2 sensors and the PCM are not broken by doing a trace with a multimeter. This is a common issue and not easy to visually identify.
4th: Check to see that your catalytic converters are not blocked. Another common issue that seems to mirror your symptoms. You will need to access the cats and take a look. Scope type cameras are available from Amazon for about $20 or so.

These are the areas in which I would start.

Thank you I really appreciate it

 

[Rubicon88]

You don't need to scope a cat.
An infrared thermometer will do the trick. A clogged cat will be much hotter on the engine side than the exit of it.

If you're still not confident and want more work just unbolt the cats and drive it. You'll know immediately!!!

If yoh don't have a temp gun get one! You'll find a lot more uses for it down the road.

 

[glowell222]

You don't need to scope a cat.
An infrared thermometer will do the trick. A clogged cat will be much hotter on the engine side than the exit of it.

If you're still not confident and want more work just unbolt the cats and drive it. You'll know immediately!!!

If yoh don't have a temp gun get one! You'll find a lot more uses for it down the road.

That's good advice, and thanks.

 

[glowell222]

Thank you I really appreciate it

Most welcome, and please let us know what you find, as your resolution may help someone else with the same types of problems.

 

[A2frontrange]

I have a 2003 Jeep Wrangler tj and it has been running sluggish for months now I replaced the o2 sensors cleaned the throttle body and the iac it still running sluggish and the rpms bounce up and down when you first start it up after it warms up it gets better. It just has a bad idle when you start it up and my gas mileage and power has tanked. What else should I change.

I just replaced the fuel pump as it tested at 44 psi and should 54. Its definitely got more pep. Check that fuel psi
Although with the 03 your cats are prone to clogging...

 

[defenderu]

I know we dont like to pay people in here but I recently bought a TJ that was running like you explained. Sluggish excess exhaust black stuff coming out of exhaust hard idle etc. Took it to a shop paid them $400 bucks and the thing runs great now. I know they changed plugs cleaned throttle body, changed belts, etc etc. No more hard idle no more black sludge out of exhaust.

 

[Rubicon88]

The other thing I forgot to mention.
Get (6) ZFR5N plugs unless you've already done so.