I am getting multiple misfire codes, but the car runs perfect. P0300,301,302, 303 and 306. Its the 4.2. No misfire, no cold start issues, no hot issues, nothing. I just replaced the intake gaskets hoping that solved the problem but it did not. Whats weird is the car runs fine, and i can clear the codes and it takes about 200 miles for them to come back. It need to get it smogged but i cant till the codes are gone.
Any ideas?????

Thanks from a new member
Gregg

 

Might want to go and list the year and anything else about the car in your signature. When you cnaged the gaskets did you change anything else while you had it open?

 

+1 to Amadauss - additionally, check the condition of your battery (outside shot) - I would also check to ensure the fuel injector electrical connectors on all 8 injectors are tight and snug - finally, misfire codes could be so intermittient that you are not "feeling" them (cause they are "balancing"' themselves out) but causing the CEL to light up - get a COP (coil on plug) tester and test each coil at idle.

Just my $0.02

 

Mine throws these when it gets close to maintenance time, my jag tech said he believes they're just " historic" codes.

 

Welcome to the Forum, Gregg.
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They're not historic if it throws them. No way. (They will be remembered i.e. put into history but that's an irrelevant detail.)

The car's more sensitive at detecting misfires & sooner than a driver...

 

Its an 05 with 200k on it, i just got it as part of a trade. I replaced the lower intake gaskets and both water pumps. I removed the plugs and they looked okay, but i know that does not mean much. I understand the historic codes, but the smog ***** in california don't. The computer must been clean and have run all self tests to pass.