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Tim Mohr
Tim Mohr, ASE MASTER TECH
Category: Ford
Satisfied Customers: 12818
Experience:  30 YRS EXPERIENCE, FOREIGN AND DOMESTIC, GAS AND DEISEL
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what is codes p0304, p0305, p0308 mean

Customer Question

what is codes p0304, p0305, p0308 mean
Submitted: 2 years ago.
Category: Ford
Expert:  Tim Mohr replied 2 years ago.
Hi, my name is XXXXX XXXXX codes are for a missfire on cylinders #4, #5 and #8, how many miles do you have on this?
Customer: replied 2 years ago.
114000 but at first, about 2 months ago, it was just the 4th. then, we saw that the piece the spark plug connects to the coil pack was loose. well, supposedly that was fixed, but then another friend looked at car and unplugged each plug one at a time, and everyone except the 3rd one showed signs of being unplugged. but then car started acting like it was running out of gas, so we plugged the code reader/scanner in, and it popped up with those codes
Expert:  Tim Mohr replied 2 years ago.
has the spark pkugs ever been replaced?
Customer: replied 2 years ago.
actually, I guess in 2008, but then the car sat from then until about 2 months ago
Customer: replied 2 years ago.
oh, we just replaced the coil pack and spark plug on #4
Expert:  Tim Mohr replied 2 years ago.
if it were a fuel problem, it would most likely set a P0300, which is for a misc missfire, since it has the 304,305 and 308, these are hard code for the idividual cylinders, and is either going to be igniton problem or compression, have you checked the compression on each of these cylinders yet?
Customer: replied 2 years ago.
I believe so, about a month or 2 ago, and #4 had lower compression
Expert:  Tim Mohr replied 2 years ago.
Do you remember what the reading was?
Customer: replied 2 years ago.
no, I dont. I didnt see, I was just told about it.
Expert:  Tim Mohr replied 2 years ago.
then this is most likely the problem, you need to check the compression again, if its low on the 4,5 and 8 cylinder, then this will cause these codes, and it will be a mechanical problem in the engine,Tim
Customer: replied 2 years ago.
so, if thats what it is, what do I need to do to,fix it?
Expert:  Tim Mohr replied 2 years ago.
if it has low compression, you need to determine if its a bad valve or a bad piston ring, to do this, squirt about a tespoon of oil in the low cylinder and rerun the compression check, if the compression comes up, then its bad piston rings, if it doesnt, then you have a problem in the valves, and the heads will have to come off, and a valve job done,Tim
Tim Mohr, ASE MASTER TECH
Category: Ford
Satisfied Customers: 12818
Experience: 30 YRS EXPERIENCE, FOREIGN AND DOMESTIC, GAS AND DEISEL
Tim Mohr and 9 other Ford Specialists are ready to help you
Expert:  Tim Mohr replied 2 years ago.
Do you need any further help?
Customer: replied 2 years ago.
do u know about how much piston rings and valves cost? I have someone to do the job, just need parts. and do I do all 3?
Expert:  Tim Mohr replied 2 years ago.
if you are replacing the three, you need to do all 8, with the piston rings, you will ned the rings which are about 200 for the set, and a complete gasket set for about 130 dollars, as for the valves, a complete valve grind set is about 300 dollars, this will incluse the valve seals and all gaskets to do the job,Tim

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