I have a 2007 Charger 3.5 for some reason it idles really rough, when I am driving it, it runs fine. If I'm stopped at a red light it is really rough. I have replaced all the spark plugs thinking that it was misfiring but that did not seem to help. The check engine light will come on every once in a while but not all the time. I thought maybe the fuel injectors needed to be cleaned, so did that, and did not help. What could it be?

 

Could be one of a millions things. Hard to tell.

What I would suggest is to have your car scanned for codes. If your CEL is coming on once in a while, there are stored codes. Most likely, those codes will tell you what is going on.

This is the only good thing about Dodge having EVERYTHING connected to the computer. You should be able to pin point a location of the problem. Get your codes, come back here and there is a thread at the top of the section with all the DTC codes.

 

OK At the shop now... Code 1 says random multiple misfire, code 2 says cylinder 1 misfire detected. What does this mean exactly? Shop guy said he thinks it's the oxygen sensor... What do y'all think?

 

P0300 & p0301 were the codes that came up by the way

 

I'm not sure on that one. Have to wait for someone a little more technical than me on this problem.

 

Usually when an O2 is bad you will get a code along with it. Especially if it is bad enough to cause misfires. The PCM monitors them heavily these days including the heater operation. Unless this guy at your shop sees something on the data stream that would indicate an O2 problem, I have no idea why he would mention it or even be going there. I bet you have a broken valve spring or a bad seat in #1 cylinder. Keep us updated.

 

So it only Mis-fire at Idle? I would think you might have a Vacuum leak somewhere.

O2 sensor wise, I doubt it. You have 2 O2 sensor monitoring each bank, 2 of them go bad at once?

Maybe you could have Engine Mechanical problems as TNtech stated. I've seen Coil or Fuel Injector goes bad once in a while, but all 3 of the problem above are quite uncommon for the 3.5l

 

New discovery on the car... when I cut the A/C on and the compressor kicks on it idles fine, once the compressoe kicks off it idles rough again.

 

Well that's bass ackwards. Most cars do it the other way around... LOL

 

I'm with you...but not entirely backwards. Assuming his statement is correct though. There is a zener diode inline on the compressor clutch that is supposed to prevent induction backfeeding after the coil collapses. Well, they used to be inline years ago. I think they are integral to the coil now. If it is not working the PCM can get spiked.