1996 Ford Taurus misfire code P0304

Tiny
PINTOBOBSTER
  • MEMBER
  • 1996 FORD TAURUS
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 12,300 MILES
How do I fix a diagnosis code P0304 a misfire in 4 in a 1996 Taurus with 3.0L compression good 120 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 ALL ADJACENT CYLINDERS ON BANK ONE, I HAVE NOT TRIED THE OIL TRICK YET AS ALL WERE RITE WITH IN EQUAL PRESSURE.


hi,
yes I am working on the first cylinder front of car passenger side closest to the alt, another question ive taken the injector plug wires and switched them number four 4 with number five 5 and I still get a reading of P0304, which means number four 4 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 wouldnt number fours 4 wire become number five or would number four 4 even tho hooked to 5 injector think it was number 4 still? Have I confused you yet? What im 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 hoofed 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?
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Thursday, December 11th, 2008 AT 8:10 PM

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Tiny
DAVE H
  • EXPERT
Fuel Injectors
The PCM controls fuel injector ON time to meter fuel quantity into intake ports. The PCM receives inputs from engine sensors to compute fuel flow necessary to maintain correct air/fuel ratio throughout entire engine operating range. Injector ON time pulse width is the only controlled variable in fuel delivery system.
Each cylinder has a solenoid-operated injector that sprays fuel toward the back of each intake valve. Fuel injector nozzles are solenoid-operated valves, which meter and atomize fuel delivered to engine. Each injector receives battery voltage through an ignition switch circuit. The PCM-controlled ground circuit is used to complete the circuit and energize the injector.
Injector bodies consist of solenoid-actuated pintle and needle valve assembly. Injector flow orifice is fixed and fuel pressure at injector tip is constant. Fuel flow to engine is regulated according to length of time solenoid is energized. This period is known as pulse width. Atomized spray pattern is obtained by shape of pintle.
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Thursday, December 11th, 2008 AT 9:10 PM
Tiny
PINTOBOBSTER
  • MEMBER
Thank you,
so with all the schooling of the reason and how and why the injectors work in a 3.0L pcm controlled engine with all the data that I have gave, where and what would you suggest I look that at next that would stop the timing of the fuel and the shut off to the injector number 4 of my engine?

I have read the books and found that the problem is number 4 injector stops working ONLY, thus I hav changed all in my previous text and it still has not fix?In your opinion since I changed the things I have were would you search next? Suggesting you did not have $700.00 for shop repair fees. I can do most r/r myself and what I learn I wont forget hands on operations, I can pretty much read the same in my auto repair book, would you check the PCM? The exhaust? I have checked for vacuum/pressure leaks!

Thank you for your fast and knowledgeable reply.
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Friday, December 12th, 2008 AT 2:04 AM
Tiny
DAVE H
  • EXPERT
The PCM pulses each injector at a set time. So if you take #4 pulse wire and swap it with #5 you should get a misfire on 4 & 5. You cannot just swap the pulse feeds over. They will be pulsing at incorrect times? Just the same as if you swap #4 plug wire with #5 you will get a misfire. Have you checked/cleaned the CKP (crankshaft position sensor)?

Misfire Detection Monitor
The misfire monitor is an on-board strategy designed to monitor engine misfire and identify the specific cylinder in which the misfire has occurred. Misfire is defined as lack of combustion in a cylinder due to absence of spark, poor fuel metering, poor compression, or any other cause. The misfire monitor will be enabled only when certain base engine conditions are first satisfied. Input from the ECT, MAF, and CKP sensors is required to enable the monitor. The misfire monitor is also performed during on demand self-test. The PCM synchronized ignition spark based on information received from the CKP sensor. The PIP signal generated is also the main input used in determining cylinder misfire. The input signal generated by the CKP sensor is derived by sensing the passage of teeth from a 36 minus 1 tooth crankshaft position wheel mounted on the end of the crankshaft.
The input signal to the PCM is then used to calculate the time between PIP edges and also crankshaft rotational velocity and acceleration. By comparing the accelerations of each cylinder event, the power loss of each cylinder is determined. When the power loss of a particular cylinder is sufficiently less than a calibrated value and other criteria is met, then the suspect cylinder is determined to have misfired. The following examples are probable conditions:
Misfire Type A

Upon detection of a Misfire type A: (200 revolutions) which would cause catalyst damage, the MIL will blink once per second during the actual misfire, and a DTC will be stored.
Misfire Type B

Upon detection of a Misfire type B: (1000 revolutions) which will exceed the emissions threshold or cause a vehicle to fail an inspection and maintenance tailpipe emissions test, the MIL will illuminate and a DTC will be stored.
The DTC associated with multiple cylinder misfire for a Type A or Type B misfire is DTC P0300, and DTCs associated with an individual cylinder misfire for a Type A or Type B misfire are DTCs P0301, P0302, P0303, 0304, 0305, P0306, P0307, and P0308.
CIRCUIT TEST HD - MISFIRE MONITOR
Diagnostic Aids
Perform this test when instructed during QUICK TEST or if directed by other test procedures. Only use this test to diagnose:
Ignition system.
Fuel pressure.
Fuel injectors.
Engine vacuum system.
Evaporative system.
Canister purge solenoid.
Internal engine wear.
Fig. 48: Identifying CKP Sensor & Crankshaft Wheel
MISFIRE TROUBLE CODES
Service DTCApplication
P0301Cylinder No. 1 (Test Pin No. 75)
P0302Cylinder No. 2 (Test Pin No. 101)
P0303Cylinder No. 3 (Test Pin No. 74)
P0304Cylinder No. 4 (Test Pin No. 100)
P0305Cylinder No. 5 (Test Pin No. 73)
P0306Cylinder No. 6 (Test Pin No. 99)
P0307Cylinder No. 7 (Test Pin No. 72)
P0308Cylinder No. 8 (Test Pin No. 98)
P0300Multiple Cylinder Misfire Or Defective CKP Sensor

Step 1) Check Possible Cause Of Misfire If vehicle runs out of fuel, a trouble code may be stored in PCM memory. If vehicle has recently run out of fuel, clear PCM memory. If vehicle has not recently run out of fuel, go to next step.
Step 2) Check For Continuous DTCs If continuous codes are present, service as necessary. Disregard misfire codes at this time. If no other misfire codes are present, go to next step.
Step 3) Check For KOEO DTCs If any KOEO DTCs are present, service as necessary. Disregard misfire codes at this time. If no KOEO DTCs are present, check spark plugs and spark plug wires. If spark plugs and spark plug wires are okay, go to next step.
Step 4) Check For KOER DTCs If any KOER DTCs except P1131 or P1151 are present, service as necessary. Disregard misfire codes at this time. If KOER DTCs P1131 or P1151 are present, go to step 8). If no KOER DTCs are present, check spark plugs and spark plug wires. If spark plugs and spark plug wires are okay, go to next step.
Step 5) Check/Compare PID Values Turn ignition and all accessories off. Connect scan tester to DLC. Ensure engine is warmed to operating temperature. Turn ignition on. Using scan tester, access and record DPFEGR PID. Start engine and allow to idle. Record DPFEGR PID. If both DPFEGR PID voltage values are within 0.15 volts of each other, go to step 8). If DPFEGR PID voltage is not as specified, go to CIRCUIT TEST HE, step 100).
NOTE:A break in step numbering sequence occurs at this point. Procedure skips from step 5) to step 8). No test procedures have been omitted.

Step 8) Check Fuel Injector & Circuit Resistance Turn ignition off. Disconnect PCM 104-pin connector. Inspect pins for damage and repair if necessary. Install EEC-V Breakout Box (014-00959), leaving PCM disconnected. Measure and record resistance between suspected fuel injector test pin and test pin No. 71 and 97 at breakout box. If resistance is 11-18 ohms, go to step 9). If resistance is not 11-18 ohms, go to step 47) under CIRCUIT TEST H.
Step 9) Check Fuel Injector Drive Signal With ignition off, connect PCM to breakout box. Connect a non-powered 12-volt test light between test pin No. 71 or 97 and suspect fuel injector test pin at breakout box. Crank or start engine. If test light glows dimly, system is operating correctly. Clean fuel injectors and repeat QUICK TEST. If test light does not glow dimly (no light/bright light), replace PCM and repeat QUICK TEST.
Step 10) Check Fuel Pressure Turn ignition off. Release fuel pressure. Install fuel pressure gauge. Start engine and allow to idle. Note fuel pressure gauge reading. Increase engine speed to 2500 RPM and maintain for one minute. For fuel pressure specifications, see FUEL PRESSURE SPECIFICATIONS article. If fuel pressure is within specification, go to next step. If fuel pressure is not within specification, go to step 2) under CIRCUIT TEST HC.
Step 11) Check System Ability To Hold Fuel Pressure Start engine and allow to idle. Note fuel pressure gauge reading. Increase engine speed to 2500 RPM and maintain for one minute. Check for fuel leaking from around fuel injectors, fuel pressure regulator and fuel hoses. Repair if necessary. Turn ignition off. Turn ignition on and note fuel pressure gauge reading. If fuel pressure remains at specification for one minute, go to next step. If fuel pressure does not remain at specification for one minute, go to step 3) under CIRCUIT TEST HC.
Step 12) Check Fuel Injector Flow & Leakage Turn ignition off. Use Rotunda Injector Tester (113-00001) to flow test fuel injectors. If flow rate for each fuel injector is okay, go to step 20). If flow rate for any fuel injector is not okay, replace defective fuel injector and repeat QUICK TEST.
NOTE:A break in step numbering sequence occurs at this point. Procedure skips from step 12) to step 20). No test procedures have been omitted.

Step 20) Check Vacuum System Inspect all vacuum hoses for kinks or damage. Ensure all vacuum connections are clean and tight. Repair or replace as necessary. If vacuum system is okay, go to next step.
NOTE:The misfire monitor can be affected by the evaporative emission system.

Step 21) Check Evaporative Emission System Inspect carbon canister. Replace carbon canister if it contains liquid fuel. If carbon canister is okay, go to next step.
Step 22) Pressure Test Evaporative System Remove vapor line from canister and install vacuum tee. Connect a pressure gauge to one side of tee and low pressure air pump to other side of tee. Apply 0.75 psi (5.2 kPa). If evaporative emission system holds pressure, reconnect vapor line and go to next step. If system does not hold pressure, isolate fault and repair as necessary.
Step 23) Check Vacuum In Evaporative System Inspect vacuum hoses between engine and carbon canister for restrictions or damage. Ensure all vacuum connections are clean and tight. Repair or replace as necessary. If system is okay, go to next step for vehicles with EVAP canister purge solenoid, or step 26) for vehicles equipped with Vapor Management Valve (VMV).
Step 24) Check Canister Purge Solenoid (CANP) Turn ignition off. Disconnect CANP solenoid wiring harness connector. Inspect connector for damaged pins and repair as necessary. Using jumper wire, apply 12 volts to VPWR (Red wire) terminal of CANP wiring harness connector. Connect CANP (Gray/Yellow wire) terminal to ground. Connect vacuum pump to manifold side of CANP solenoid and apply 16 in. Hg. When 12 volts is applied, solenoid should open and pass air freely. Replace solenoid if it does not function correctly. If solenoid does function correctly, go to next step.
Step 25) Check Engine Condition Inspect engine for obvious faults. Ensure compression is even and within specification. Check PCV system for restrictions or leaks. Repair or replace as necessary. If no faults can be found, misfire trouble code is intermittent. Go to CIRCUIT TEST Z.
Step 26) Check Vapor Management Valve (VMV) Housing Turn ignition off. Ensure vehicle is at room temperature. Connect vacuum pump to fuel vapor port of VMV and apply 16 in. Hg. If vacuum is held, go to next step. If vacuum is not held, replace VMV and repeat QUICK TEST.
Step 27) Leave ignition off. Disconnect hose from vacuum input port of VMV. Connect vacuum pump to VMV vacuum input port and apply 10-15 in. Hg. If little or no vacuum is lost, service VMV filter. If filter is okay, replace VMV. Repeat QUICK TEST. If vacuum is not as specified, go to step 25).
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Friday, December 12th, 2008 AT 3:02 PM

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