Mechanics

I CANT FIGURE OUT MY RANDOM CYLINDER MISFIRE IN ALL 6 CYLINDERS.

1996 Chrysler Sebring • 166,000 miles

My vehicles check engine light flashes quite often at random times, and random speed. It gives me random cylinder misfire codes from P0300 to P0306. I have changed the EGR valve, distributer cap, rotor, plugs, and wires and would like to know where to go from here.
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Kodyclarence
October 7, 2012.




Try swapping the # 6 injector with another cylinder and if problem migrates, the injector is bad.
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KHLow2008
Oct 12, 2012.
Its a random cylinder misfire in all 6 cylinders.

Tiny
Kodyclarence
Oct 12, 2012.
Random misfires are usually fuel related. Vacuum leaks can contribute to this. Check out the following to see if you can find anything. If you want more information on any procedures refered to, let me know.

TEST TC-106A - MULTIPLE CYLINDER MISFIRE

1. Repair any other Diagnostic Trouble Codes (DTCs) before proceeding with this test. This DTC will only set if condition occurs during 2 driving cycles. Using scan tool, erase trouble codes.

2. Start engine. Drive vehicle until normal operating temperature is reached. Ensure engine speed goes more than 1200 RPM. Drive vehicle at a steady rate at various MAP and RPM ranges. DO NOT perform any sharp maneuvers with vehicle, these actions will disable misfire detection. During road test, pull vehicle to side and turn ignition off, then restart engine and continue driving vehicle. Go to next
step.

3. Using scan tool, read trouble codes. If MULTIPLE CYLINDER MISFIRE DTC returned, go to step 8). If MULTIPLE CYLINDER MISFIRE DTC did not return, go to next step.

4. If CYLINDER NO. 1-6 MISFIRE DTC returned, go to TEST TC-107A. If
CYLINDER NO. 1-6 MISFIRE DTC did not return, connect an engine analyzer to vehicle. Start engine. Using equipment manufacturer's instructions, analyze secondary ignition pattern. If secondary ignition pattern is okay, go to next step. If secondary ignition pattern is not okay, repair secondary ignition system as
necessary. Perform TEST VER-2A.

5. Using a spray bottle with water, spray secondary ignition cables. DO NOT spray inductive pickup of test equipment. If ignition pattern did not change, go to next step. If ignition pattern changed, repair secondary ignition system as necessary. Perform TEST VER-2A.

6. Condition to set trouble code is not present at this time. MULTIPLE CYLINDER MISFIRE DTC sets when a more than 1-3 percent misfire rate is measured during 2 trips or with a 3-14 percent misfire rate during one trip and at least 2 cylinders are misfiring. Possible causes are: ignition coil circuit failure, failed spark plug or wire, malfunctioning fuel pump or restricted fuel filter,
mechanical engine failure, EGR malfunction, injector malfunction, restricted exhaust, low vehicle fuel level, intake restriction, poor Powertrain Control Module (PCM) power grounds, malfunctioning EVAP system or failed PCM. Go to next step.

7. Inspect all related wiring and connectors and repair as necessary. If no problems were found with wiring and connectors, see
INACTIVE TROUBLE CODE CONDITION. Test is complete. Perform TEST VER-2A. If related wiring and connectors were repaired, perform TEST VER-2A.

8. Turn ignition off. Connect an engine analyzer to vehicle. Start engine and let it idle. If engine will not idle, maintain a constant engine RPM. Inspect ignition cables for proper location. If ignition cables are properly routed, go to next step. If ignition cables are not properly routed, repair as necessary. Perform TEST VER-2A.

9. Using scan tool, monitor Idle Air Control (IAC) motor. Disconnect one injector at a time, then reconnect. If IAC motor stepped up idle for each injector, go to next step. If IAC motor did not step up idle for each injector, before replacing injector(s), ensure no mechanical problems are present with cylinder. Replace injector(s) as necessary. Perform TEST VER-2A.

10. Connect an engine analyzer to vehicle. Start engine. Using equipment manufacturer's instructions, analyze secondary ignition pattern. If secondary ignition pattern is okay, go to next step. If secondary ignition pattern is not okay, repair secondary ignition system as necessary. Perform TEST VER-2A.

11. Using a spray bottle with water, spray secondary ignition cables. DO NOT spray inductive pick-up of test equipment. If ignition pattern did not change, go to next step. If ignition pattern changed, repair secondary ignition system as necessary.
Perform TEST VER-2A.

12. Turn engine off. Connect a vacuum gauge to engine intake. Start engine and run until normal operating temperature is reached. Apply parking brake. Put transmission in Neutral. Observe vacuum
gauge. If vacuum gauge reads at least 13 in. Hg, to next step. If vacuum gauge does not read at least 13 in. Hg, repair restricted exhaust system. Perform TEST VER-2A.

13. Turn ignition off. Release fuel pressure. Connect a fuel pressure gauge to fuel rail service port. Turn ignition on. Using
scan tool, activate fuel system test. Allow time for fuel pressure gauge to stabilize. Using scan tool, stop fuel system test. Monitor fuel pressure gauge for one minute. If fuel pressure is 10 psi or less, go to next step. If fuel pressure is less than 10 psi, go to TEST NTC-3A.

14. Inspect air cleaner filter and inlet ducts for restrictions. If no restrictions were present, go to next step. If restrictions are present, clean restriction as necessary. Perform TEST VER-2A.

15. Verify all wiring and connectors are okay. Perform following tests in order until problem is found: Secondary ignition patterns. Perform TEST NTC-2A.
Fuel pressure. Perform TEST NTC-3A.
PCM grounds and power circuits. Perform TEST NTC-11A.
EGR system. Perform TEST NTC-13A.
No trouble code mechanical. Perform TEST NTC-18A.

KHLow2008
Oct 13, 2012.

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