Missfires 300 + 305
Thread Starter
JK Newbie
Joined: Oct 2014
Posts: 9
Likes: 0
From: Connecticut
Missfires 300 + 305
Hey, I recently picked up my new JK.
Its an 07. After a 2 hour ride home, I stopped by pep boys and used their obd reader.
Got 3 codes..
300
305
305
Ive done lots of googling and I havent been able to find anyone with 2 "305" codes. I have to complete Connecticut emissions within the next 9 days.
I was wondering if anyone has an idea on what I could do.. I would like to get it fixed but more importantly pass emissions.
I don't want to start replacing parts left and right just guessing, I know it can be lots of things. I used 93 and I read that can cause a problem sometimes. I may be wrong.
If anyone could please help me out I would much appreciate it.
Thanks!
Its an 07. After a 2 hour ride home, I stopped by pep boys and used their obd reader.
Got 3 codes..
300
305
305
Ive done lots of googling and I havent been able to find anyone with 2 "305" codes. I have to complete Connecticut emissions within the next 9 days.
I was wondering if anyone has an idea on what I could do.. I would like to get it fixed but more importantly pass emissions.
I don't want to start replacing parts left and right just guessing, I know it can be lots of things. I used 93 and I read that can cause a problem sometimes. I may be wrong.
If anyone could please help me out I would much appreciate it.
Thanks!
JK Junkie
Joined: Dec 2008
Posts: 2,191
Likes: 6
From: Boston, MA
Hey, I recently picked up my new JK. Its an 07. After a 2 hour ride home, I stopped by pep boys and used their obd reader. Got 3 codes.. 300 305 305 Ive done lots of googling and I havent been able to find anyone with 2 "305" codes. I have to complete Connecticut emissions within the next 9 days. I was wondering if anyone has an idea on what I could do.. I would like to get it fixed but more importantly pass emissions. I don't want to start replacing parts left and right just guessing, I know it can be lots of things. I used 93 and I read that can cause a problem sometimes. I may be wrong. If anyone could please help me out I would much appreciate it. Thanks!
The stock tune is for 87 octane. No real benefit in using higher unless you trying to stop a knocking problem. Even then, the JK has a knock sensor that should alert the PCM to deal with it, within reason.
Thread Starter
JK Newbie
Joined: Oct 2014
Posts: 9
Likes: 0
From: Connecticut
Start with pulling the spark plugs. If they look ok, it could be an injector or the fuel/air ratio.
The stock tune is for 87 octane. No real benefit in using higher unless you trying to stop a knocking problem. Even then, the JK has a knock sensor that should alert the PCM to deal with it, within reason.
The stock tune is for 87 octane. No real benefit in using higher unless you trying to stop a knocking problem. Even then, the JK has a knock sensor that should alert the PCM to deal with it, within reason.
Thanks guys, i'll update whether this worked or not.
JK Junkie
Joined: Dec 2008
Posts: 2,191
Likes: 6
From: Boston, MA
JK Junkie
Joined: Dec 2008
Posts: 2,191
Likes: 6
From: Boston, MA
From my 2008 manual:
EMISSIONS INSPECTION AND MAINTENANCE PROGRAMS
In some localities, it may be a legal requirement to pass an inspection of your vehicle’s emissions control system. Failure to pass could prevent vehicle registration.
For states that require an Inspection and Mainte- nance (I/M), this check verifies the Malfunction Indicator Light (MIL) is functioning and is not on
when the engine is running, and that the OBD II system is ready for testing.
Normally, the OBD II system will be ready. The OBD II system may not be ready if your vehicle was recently serviced, recently had a dead battery, or a battery replace- ment. If the OBD II system should be determined not ready for the I/M test, your vehicle may fail the test.
Your vehicle has a simple ignition key-actuated test, which you can use prior to going to the test station. To check if your vehicle’s OBD II system is ready, you must do the following:
1. Insert your ignition key into the ignition switch.
2. Turn the ignition to the ON position, but do not crank or start the engine.
3. If you crank or start the engine, you will have to start this test over.
4. As soon as you turn your key to the ON position, you will see the MIL symbol come on as part of a normal bulb check.
5. Approximately 15 seconds later, one of two things will happen:
a. The MIL will flash for about 10 seconds and then return to being fully illuminated until you turn OFF
the ignition key or start the engine. This means that your vehicle’s OBD II system is not ready and you should not proceed to the I/M station.
b. The MIL will not flash at all and will remain fully illuminated until you turn OFF the ignition key or start the engine. This means that your vehicle’s OBD II system is ready , and you can proceed to the I/M station.
If your OBD II system is not ready, you should see your authorized dealer or repair facility. If your vehicle was recently serviced or had a battery failure or replacement, you may need to do nothing more than drive your vehicle as you normally would in order for your OBD II system to update. A recheck with the above test routine may then indicate that the system is now ready.
Regardless of whether your vehicle’s OBD II system is ready or not ready, if the MIL is illuminated during normal vehicle operation, you should have your vehicle serviced before going to the I/M station. The I/M station can fail your vehicle because the MIL is on with the engine running.
EMISSIONS INSPECTION AND MAINTENANCE PROGRAMS
In some localities, it may be a legal requirement to pass an inspection of your vehicle’s emissions control system. Failure to pass could prevent vehicle registration.
For states that require an Inspection and Mainte- nance (I/M), this check verifies the Malfunction Indicator Light (MIL) is functioning and is not on
when the engine is running, and that the OBD II system is ready for testing.
Normally, the OBD II system will be ready. The OBD II system may not be ready if your vehicle was recently serviced, recently had a dead battery, or a battery replace- ment. If the OBD II system should be determined not ready for the I/M test, your vehicle may fail the test.
Your vehicle has a simple ignition key-actuated test, which you can use prior to going to the test station. To check if your vehicle’s OBD II system is ready, you must do the following:
1. Insert your ignition key into the ignition switch.
2. Turn the ignition to the ON position, but do not crank or start the engine.
3. If you crank or start the engine, you will have to start this test over.
4. As soon as you turn your key to the ON position, you will see the MIL symbol come on as part of a normal bulb check.
5. Approximately 15 seconds later, one of two things will happen:
a. The MIL will flash for about 10 seconds and then return to being fully illuminated until you turn OFF
the ignition key or start the engine. This means that your vehicle’s OBD II system is not ready and you should not proceed to the I/M station.
b. The MIL will not flash at all and will remain fully illuminated until you turn OFF the ignition key or start the engine. This means that your vehicle’s OBD II system is ready , and you can proceed to the I/M station.
If your OBD II system is not ready, you should see your authorized dealer or repair facility. If your vehicle was recently serviced or had a battery failure or replacement, you may need to do nothing more than drive your vehicle as you normally would in order for your OBD II system to update. A recheck with the above test routine may then indicate that the system is now ready.
Regardless of whether your vehicle’s OBD II system is ready or not ready, if the MIL is illuminated during normal vehicle operation, you should have your vehicle serviced before going to the I/M station. The I/M station can fail your vehicle because the MIL is on with the engine running.
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Thread Starter
JK Newbie
Joined: Oct 2014
Posts: 9
Likes: 0
From: Connecticut
From my 2008 manual:
EMISSIONS INSPECTION AND MAINTENANCE PROGRAMS
In some localities, it may be a legal requirement to pass an inspection of your vehicle’s emissions control system. Failure to pass could prevent vehicle registration.
For states that require an Inspection and Mainte- nance (I/M), this check verifies the Malfunction Indicator Light (MIL) is functioning and is not on
when the engine is running, and that the OBD II system is ready for testing.
Normally, the OBD II system will be ready. The OBD II system may not be ready if your vehicle was recently serviced, recently had a dead battery, or a battery replace- ment. If the OBD II system should be determined not ready for the I/M test, your vehicle may fail the test.
Your vehicle has a simple ignition key-actuated test, which you can use prior to going to the test station. To check if your vehicle’s OBD II system is ready, you must do the following:
1. Insert your ignition key into the ignition switch.
2. Turn the ignition to the ON position, but do not crank or start the engine.
3. If you crank or start the engine, you will have to start this test over.
4. As soon as you turn your key to the ON position, you will see the MIL symbol come on as part of a normal bulb check.
5. Approximately 15 seconds later, one of two things will happen:
a. The MIL will flash for about 10 seconds and then return to being fully illuminated until you turn OFF
the ignition key or start the engine. This means that your vehicle’s OBD II system is not ready and you should not proceed to the I/M station.
b. The MIL will not flash at all and will remain fully illuminated until you turn OFF the ignition key or start the engine. This means that your vehicle’s OBD II system is ready , and you can proceed to the I/M station.
If your OBD II system is not ready, you should see your authorized dealer or repair facility. If your vehicle was recently serviced or had a battery failure or replacement, you may need to do nothing more than drive your vehicle as you normally would in order for your OBD II system to update. A recheck with the above test routine may then indicate that the system is now ready.
Regardless of whether your vehicle’s OBD II system is ready or not ready, if the MIL is illuminated during normal vehicle operation, you should have your vehicle serviced before going to the I/M station. The I/M station can fail your vehicle because the MIL is on with the engine running.
EMISSIONS INSPECTION AND MAINTENANCE PROGRAMS
In some localities, it may be a legal requirement to pass an inspection of your vehicle’s emissions control system. Failure to pass could prevent vehicle registration.
For states that require an Inspection and Mainte- nance (I/M), this check verifies the Malfunction Indicator Light (MIL) is functioning and is not on
when the engine is running, and that the OBD II system is ready for testing.
Normally, the OBD II system will be ready. The OBD II system may not be ready if your vehicle was recently serviced, recently had a dead battery, or a battery replace- ment. If the OBD II system should be determined not ready for the I/M test, your vehicle may fail the test.
Your vehicle has a simple ignition key-actuated test, which you can use prior to going to the test station. To check if your vehicle’s OBD II system is ready, you must do the following:
1. Insert your ignition key into the ignition switch.
2. Turn the ignition to the ON position, but do not crank or start the engine.
3. If you crank or start the engine, you will have to start this test over.
4. As soon as you turn your key to the ON position, you will see the MIL symbol come on as part of a normal bulb check.
5. Approximately 15 seconds later, one of two things will happen:
a. The MIL will flash for about 10 seconds and then return to being fully illuminated until you turn OFF
the ignition key or start the engine. This means that your vehicle’s OBD II system is not ready and you should not proceed to the I/M station.
b. The MIL will not flash at all and will remain fully illuminated until you turn OFF the ignition key or start the engine. This means that your vehicle’s OBD II system is ready , and you can proceed to the I/M station.
If your OBD II system is not ready, you should see your authorized dealer or repair facility. If your vehicle was recently serviced or had a battery failure or replacement, you may need to do nothing more than drive your vehicle as you normally would in order for your OBD II system to update. A recheck with the above test routine may then indicate that the system is now ready.
Regardless of whether your vehicle’s OBD II system is ready or not ready, if the MIL is illuminated during normal vehicle operation, you should have your vehicle serviced before going to the I/M station. The I/M station can fail your vehicle because the MIL is on with the engine running.