Hey guys I have 2004 TL with 123xxx miles. It has been running well. Recently the CEL light has come on with misfiring codes for all cylinders plus a random misfire. I went ahead and changed spark plugs and found a bad coil pack. The 105k job has also been done at 98k and car has been perfectly fine. I am still getting the codes. I also notice the car only misfires at idle and operating temperature. Any idea what it could be?

 

1) Get the codes read for free at an auto parts store or by someone with a OBD II code reader and report the code to us.
If the code readings aren't obvious, you can then do a search for the codes here on AZ or on the web generally to get an idea which part(s) may be involved.

2) My guess, without any code, is that it may be the EGR valve. Let me know if I'm right or wrong.

G/L.

 

You can check for a vacuum leak with brake clean, spray around intake. If you hear the engine review up,it got some brake clean into the cylinder. All cylinders misfire, think about what could cause all cylinders to misfire. Won't be six plugs or six coils.

Rev up. Stupid autocorrect

 

I had the codes read but I just don't remember exact numbers. But they are codes for what I mentioned above

I will try that. Thanks

 

O-I-C.
If the codes were for misfires due to a bad coil pack, then try putting the TL through the "Idle Relearn Procedure" if that was not already done: https://acurazine.com/forums/3g-tl-problems-fixes-114/rough-idle-786866/.

 

Ignition problems are usually worse when hot. Compression problems show up at idle. A stuck open EGR will be worse at idle. If you only have a misfire at idle, check compression first. The only way all 6 cylinders are going to have low compression is if you have a 6mt and overreved it.