MichiganCherokee

I have an 01 with 165k. Has had a misfire since I've purchased it.
Items I have replaced:
Mopar crank sensor
Camshaft position sensor
TPS
All new injectors
All new champion plugs
New coil rail
New battery
New Clearwater head
New map sensor

I haven't done
O2 sensors
IAC sensor

Made sure the harness is away from the motor and compression checked out at 160-165psi on all 6. Fuel pressure was within spec.
I get an intermittent issue when driving, it will run like carp and idle real rough then I'll shut it down and restart immediately and it will be fine.
Dealership says it only misfires at idle rpms one rpms are raised the misfire is absent.
Any suggestions?
With all this I'm still getting 14mpg with stock tires and stock gearing. With a nearly empty passenger compartment.

MichiganCherokee

Hooked up my obd2 when I got home today.
Codes p0300,p0301,p0306,p0455 and p1494.
Multiple misfire
Large vacuum leak
Can't remember what 1494 is for

Radi

1494 is a failed leak detection pump. 0455 is evap emissions large leak, but that's iffy if the LDP isn't working right.
99-00-01 seem to be really twitchy about setting misfire codes. There was an issue with valve springs and another with exhaust valve deposits when they don't rotate (too much low rpm driving), but that'd all continue or worsen off-idle and you have a new head anyway. How did the dealership determine it was an idle only misfire?
Where did you read the 'large vacuum leak'? Having one would certainly cause trouble. Was that the Large Evap leak you are referring to?

MichiganCherokee

Not sure how the dealership determined the miss was only at idle... :/
I have an obd2 scanner that is where I obtained the codes. I will be picking up a new gas cap today, the one I have clicks and clicks but doesn't feel like its very tight. I will also be picking up some new vacuum lines as the three on the side of the intake are dry rotted.
I don't think an IAC or 02 sensor would cause a miss correct? Thinking its more of an electrical flaw as 1&6 are missing and they fire together. I'd hate to have to open the harness and check wires but I might have to

MichiganCherokee

I have an old coil rail I can throw on this weekend see if that works..

Gee oh Dee

Have you tested any of the sensors you replaced?

Its not unheard of to get bad parts out of the box. Even from stealerships.

Just tossing thoughts out.

Or maybe there is a vacuum leak. See if you can get your hands on a smoke machine.

Muaddib420

Six and one cylinder misfire points to coil rail.

MichiganCherokee

I'll check the sensors, installed a new gas cap. Seems to have smoothed it out a little and fits a lot better.
Got pricing on new vacuum lines. I'll try my other rail tomorrow and report back.