My 2007 model was starting to have a rough idle, and would hesitate and sometimes misfire when accelerating. I fixed it today. I wanted to post my fix to help someone who might experience the same problem.

At first I changed the plug wires. I thought since I changed the plugs and wires in summer the plugs should be fine. I pulled the plug in the number 2 cylinder (P0302) an the plug looked fine. [still rough idle and misfire] Changed injector for cylinder #2. During process found that one bolt for the EGR tube was missing where EGR tube attaches to valve [oh well]. Put everything back together and it improved slightly for a week. This weekend misfired really bad on hilly terrain around the house. Today I replaced the bolts and the gasket and the rough idle and check engine light are gone! I should've started with checking/replacing the missing bolts. There should be two. Mopar P/N: 06508489AA

I hope this post helps someone.

 

Well I'm still getting misfire P0304, and now P2172 (P2172 - High Airflow / Vacuum Leak Detected (instantaneous Accumulation).

Any ideas? It hesitates and backfires through the airbox. Damn thought I fixed it.

This weekend I'm fixing cracked manifolds [installing headers]. I'm in need of a little help.

 

The misfire problem could be from the cracked manifold, although if it was because of the exhaust manifold you'd likely be getting backfire through the exhaust not the air box. There are two plastic lines that run right next to the air box that will rub and develop a leak when the tube gets a pin hole on the underside and its hard to notice even when you're looking for it. Double check the two plastic lines right near your air box/battery, its dark outside here now so I'll shoot ya a pic in the am if you can't find it

 

Thank you. I'll check it tomorrow.

 

Pic of said component would help us less experienced folks out...

 

Backfire through air box could mean timing or ignition problems

 

what i did was run a bottle of seafoam through the brake booster vacuum line and you will see every spot where there is a leak. Mine was leaking bad at the manifold and when i removed the heat shield there were two large cracks. Simple fix...used a product called thermosteel on the cracks and 8 months later it is still holding strong...nice and quiet now with no hesitation or rough idle.

 

Thanks everyone. If manifold cracks are severe enough will it cause a misfire? I've had a cracked manifold on a TJ and YJ and they ran fine. I'm installing headers this weekend, and I will check all vacuum lines this weekend while I'm at it.

 

The p2172 code is for a vacuum leak and this can cause your misfire code you are getting too. Definitely look over all your vacuum lines while your doing the headers, I'm trying to attach the pics of the plastic lines that can leak and my phone isn't attaching them. I'll send them from the computer in a little bit. One comes off the intake manifold right near the throttle body (i can't remember where the other one comes from) both meet right in front of your battery and are pre bent hard plastic. Look them over real good for thin spots especially on the bottom where you can't visually check

 

I was getting these codes awhile back and it was the PCV valve. They are only about $15 at the dealer, I'd try changing that.