2 problems 04 Wrangler 4.0

[cheechahumma]

I am getting the P0304 code - a #4 cylinder misfire. I'll start with the plug and I have also heard to check the injector. Is there anything else to check for this code? It seems to be a common problem.

Secondly. I noticed that my breaking power had diminished. Just had a feeling that the front was doing most if not all of the work. I looked at the discs and the front was shiny and the rear looked less so, like the pads weren't engaging the disc. I have no clue about the this, not something that I have researched, so all advice is welcomed.

Thanks!

 

[gatertamer]

Spark plug wires Check the resistance of them they have got me more than once maybe coil pack

 

[JSpike]

On the brakes I would clean and adjust rear brakes first . I think your Jeep has rear drum brakes, that's a maintenance thing on rear drums. You need to fill out your profile on your Jeep.
The misfire a different story, I would start with plugs and boots,you don't have plug wires, do that and see if it still misfired !

 

[cheechahumma]

Spark plug wires Check the resistance of them they have got me more than once maybe coil pack

THX!

 

[cheechahumma]

On the brakes I would clean and adjust rear brakes first . I think your Jeep has rear drum brakes, that's a maintenance thing on rear drums. You need to fill out your profile on your Jeep.
The misfire a different story, I would start with plugs and boots,you don't have plug wires, do that and see if it still misfired !

My unlimited does have rear discs.
I'll dig deeper tomorrow.

 

[TJ Jim]

Do you have the insulation around and under the injectors to block the heat from them?

 

[cheechahumma]

Do you have the insulation around and under the injectors to block the heat from them?

Not all of them. I need to redo the whole thing.

 

[cheechahumma]

I took out the cylinder 4 spark plug and it looked good. Checked the gap and it was just north of 0.050 so I narrowed it down to the rec 0.035/0.040. One weird thing, I removed the negative battery cable to reset code. and when restarting for the first time the engine had trouble running, after about the 5th time it stayed running, but definitely weird. Unless this is the comp relearning. The jeep has had 0 problems running during the time I have had it.

Running well now, the engine light has stayed off.