P0300,0302,0303,0305, and P0455??????

[NEWTOJEEPZ]

Just bought an '02 Grand Cherokee. OBDII is giving these codes. I understand the 030's are multiple misfires and the 0455 is an evap leak. Already replaced gas cap to get rid of small leak code. I guess the big question is will the gross evap leak cause the multiple misfires? Thanks in advance for any help.

 

[JPNinPA]

It can. It could act like a vac leak if it leans out the gas air ratio. P0455 is a large leak. Vac line, low vac, purge valve, canister, rubber hose connector.
Does it sound like it is misfiring?

Have you done anything to it lately that would result in misfires?

You might be able to pull the evap vacuum line and temp plug the vac port to see if the misfire goes away,

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