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post #1 of 3 (permalink) Old 12-11-08, 07:29 PM Thread Starter
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code P0304 misfire stumped

How do I fix a diagnostic code P0304 a misfire in 4 on a 1996 Taurus with 3.0L??? Compression good, 120 psi. Changed plugs, wires, egr backpressure sensor, vacuum solenoid, vehicle speed sensor, coil pack, injector, switched injector wires cleared codes, got same code only P0304 comes up, what else?

120 PSI ALL ADJACENT CYLINDERS ON BANK ONE, I HAVE NOT TRIED THE OIL TRICK YET AS ALL WERE RIGHT WITH IN EQUAL PRESSURE.

Yes, I am working on the first cylinder, front of car, passenger side closest to the alt. Another question I've taken the injector plug wires and switched them number four with number five and I still get a reading of P0304, which means number four cylinder. Question I have is are the injector wires married to or assigned to a specific cylinder? Or could I put ANY injector wire to ANY injector? If so in theory wouldn't number fours wire become number five or would number four even though hooked to 5 injector think it was number 4 still? Have I confused you yet??????? What I'm trying to say is if I move four to five does it (PCM) still think it is connected to four when in reality it is connected to five?? Or does it sense it is connected to five and not four where it use to be connected.. and still give me the code P0304, or since I switched injector wires being hooked up to five IF it was in the wiring it would read P0305?? and if in the cylinder it would still read P0304. hope this made sense???? If you or any body would like to call me let me know your eMail and I will send it to you so I can try to explain what I have written above??

Thanks for your time.
Robert
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post #2 of 3 (permalink) Old 12-12-08, 10:44 PM
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Exclamation Re: code P0304 misfire stumped

Quote:
Originally Posted by pintobobster View Post
How do I fix a diagnostic code P0304 a misfire in 4 on a 1996 Taurus with 3.0L??? Compression good, 120 psi. Changed plugs, wires, egr backpressure sensor, vacuum solenoid, vehicle speed sensor, coil pack, injector, switched injector wires cleared codes, got same code only P0304 comes up, what else?

120 PSI ALL ADJACENT CYLINDERS ON BANK ONE, I HAVE NOT TRIED THE OIL TRICK YET AS ALL WERE RIGHT WITH IN EQUAL PRESSURE.

Yes, I am working on the first cylinder, front of car, passenger side closest to the alt. Another question I've taken the injector plug wires and switched them number four with number five and I still get a reading of P0304, which means number four cylinder. Question I have is are the injector wires married to or assigned to a specific cylinder? Or could I put ANY injector wire to ANY injector? If so in theory wouldn't number fours wire become number five or would number four even though hooked to 5 injector think it was number 4 still? Have I confused you yet??????? What I'm trying to say is if I move four to five does it (PCM) still think it is connected to four when in reality it is connected to five?? Or does it sense it is connected to five and not four where it use to be connected.. and still give me the code P0304, or since I switched injector wires being hooked up to five IF it was in the wiring it would read P0305?? and if in the cylinder it would still read P0304. hope this made sense???? If you or any body would like to call me let me know your eMail and I will send it to you so I can try to explain what I have written above??

Thanks for your time.
Robert
Moved to correct section. You can't switch injector connectors between cylinders. You can swap the injectors themselves in the rail. Even with good compressin you could have a leaking valve, rings or a head gasket issue. You need to do a cylinder leakdown test.

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post #3 of 3 (permalink) Old 12-14-08, 01:40 PM
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Re: code P0304 misfire stumped

This is a typical " throw parts at it until i run out of money " . Your engine is sequential
firing. You can not switch injector wires as TBIRD says. You will never fix this until you have the proper code scan done. Unless you have a scanner that does " real time " you should send it out. A scanner like that is about $3000.00 if you know how to read it. Have you called the dealer to see if there is a T.S.B. on this car that spits out false codes ? G.M. is famous for that. some Fords too. Have you done a balance test ? I'd say
you replaced every part that car doesn't need. Well at least you now know everything is new.
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