Misfire on cold start

smyth22

New Member
Joined
Dec 5, 2022
Messages
2
Location
Ontario
2004 Jeep Wrangler 4.0
Hello guys, first time ever posting in a forum so I'll jump right into the issue.

In the past week it's been below 0° in the mornings, when I start my jeep on the cold mornings I get a misfire out of cylinder 2 and 3, once the engine warms up it seems to run fine, maybe a bit of power lost but once it's warm the engine runs good, no misfires or anything.
What could it be?
I'm throwing evap codes as well as misfire codes.

Screenshot_20221204_080339.jpg
 
Do you smell fuel vapors around the gas tank or the engine area? Possible broken vapor line or fitting and verify the vacuum lines to the purge valve and solenoid are intact.
The cylinder misfires in cold weather could be caused by dirty spark plugs, leaking or sticking rings (low cylinder pressure) until the engine warms up and rings seal better.
 
2004 Jeep Wrangler 4.0
Hello guys, first time ever posting in a forum so I'll jump right into the issue.

In the past week it's been below 0° in the mornings, when I start my jeep on the cold mornings I get a misfire out of cylinder 2 and 3, once the engine warms up it seems to run fine, maybe a bit of power lost but once it's warm the engine runs good, no misfires or anything.
What could it be?
I'm throwing evap codes as well as misfire codes.

View attachment 382022

Pull the plugs and compare all comparing 2 & 3 to the others. Look for signs of coolant on them or being very clean. Could have a head gasket starting to leak. Evap leak check gas cap seal and the filler neck.
 
Do you smell fuel vapors around the gas tank or the engine area? Possible broken vapor line or fitting and verify the vacuum lines to the purge valve and solenoid are intact.
The cylinder misfires in cold weather could be caused by dirty spark plugs, leaking or sticking rings (low cylinder pressure) until the engine warms up and rings seal better.

No fuel vapors but yesterday I did start to hear something from the back of the jeep when accelerating, kinda sounded like the fuel pump was sucking super hard and was struggling to get fuel but I just had the fuel pump replaced a couple months ago.