P0303 p0420

autojoe

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#1
Make
Jeep
Model
Liberty
Year
2006
Miles
100000
Engine
3.7
Starts runs fine until you shut it off then with engine hot starts fine but under load misfiring mil flashing. If you don't shut off engine hot will not act up until you shut off restart and under load will misfire. If let set a couple hours will not act up. Any ideas? Thanks Joe
 

grcauto

Hero Member
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May 29, 2014
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#2
Get the codes.....Possible bad coil.
 

autojoe

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#3
All plugs and coils were replaced by garage. Won't misfire until shut off when engine hot no problem restart just will misfire under load but only after it has been shut off and restarted. Can drive for ever if you don't shut off. If you let sit for hours it is okay.
 
Joined
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#4
Perhaps a harness problem during the conditions you described. Circuit to #3 coil or injector affected. "Short" during torque load after hot shutdown superheat.
 

autojoe

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#5
Can drive continously without any problem just don't shut down. Starts up no problem then problem only under load condition.
 
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#6
So...some car part works "good enough" from cold to hot that misfire under load does not occur, but if the engine stops running, that part heats up to superhot and it no longer works good enough to operate without misfire under load occurring. That part only returns to "good enough" after it cools completely. What could that car part be?