Big Willy
Jeeper
My idea of a symphony? Six pistons playing a tune my right foot tells it.
Posts: 1,510
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OBDII
May 14, 2010 9:22:18 GMT -4
Post by Big Willy on May 14, 2010 9:22:18 GMT -4
I bought one of those OBDII readers from Can Tire when they were on sale earlier this week. Today I hook it up and I get the code P0304 which states "Cylinder 4 Misfire Detected". Does anyone know what might cause this? The following is the "Freeze Frame" info if that helps:
Freeze Frame Information
Parameter Description==================Value
DTC for which Freeze Frame was Stored======= P0304 Fuel System 1 Status==================== Closed Loop Fuel System 2 Status==================== Not Supported Calculated LOAD Value=================== 53.73 % Engine Coolant Temp==================== 203.00 °F Short Term Fuel Trim - Bank 1=============== -0.78 % Long Term Fuel Trim - Bank 1=============== -17.19 % Intake Manifold Absolute Pressure=========== 0.00 inHg Engine RPM=========================== 0.00 rpm Vehicle Speed Sensor==================== 61.52 mph
Its a 97 ZJ with the 4.0L. Any help with me understanding this or a web site that has repair solutions would be great. Thanks in advance. ;D
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OBDII
May 14, 2010 9:33:30 GMT -4
Post by mrfixit on May 14, 2010 9:33:30 GMT -4
Check engine light on?
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Big Willy
Jeeper
My idea of a symphony? Six pistons playing a tune my right foot tells it.
Posts: 1,510
|
OBDII
May 14, 2010 10:12:28 GMT -4
Post by Big Willy on May 14, 2010 10:12:28 GMT -4
Yep. Main reason I bought the reader... well that and it was on sale half price.
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Enos
Hardcore
Founding Member
Posts: 8,513
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OBDII
May 14, 2010 10:42:18 GMT -4
Post by Enos on May 14, 2010 10:42:18 GMT -4
I had the same code on my car, dealer steps were:
Replace the plugs (which I didn't let them do as that was the first thing I did, so they were 2 days old and they charge $6/plug for Champions)
Replace the plug wires
Replace the injector - problem fixed
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OBDII
May 14, 2010 11:31:35 GMT -4
Post by mrfixit on May 14, 2010 11:31:35 GMT -4
My XJ threw the same codes over the winter. A few days later she quit on me in the woods. It ended up being water/dirt in the fuel, might want to check for that first before throwing new parts/money at it. With my cheap scottish blood, I always check the free stuff first.
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Bubba
Jeeper
No more Bacon :(
Posts: 1,402
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OBDII
May 14, 2010 17:42:46 GMT -4
Post by Bubba on May 14, 2010 17:42:46 GMT -4
In my experience, a P0304 simply means that the ECU detected a missfire or the crankshaft speed slowed when cyl #4 was supposed to keep it going. Generally you'll find that it is usually a spark issue, ie plugs, wire or coil. By the looks of your freeze frame data I'd say it's not an injector issue ( longterm fuel trim is -17%) so infact the ECU is leaning the cyl out. If you have no other issues other than the miss ie no black smoke, I'd say try some new plugs. If you really want to be sure swap your cyl #4 and #1 plugs if it's drivable, drive it thought the missfire monitor (check the web for the proper procedure on this) this should bring the MIL on again and if the plug is the problem you'll get a P0301.....you can try swapping injectors too....wow I'm long winded ;D hope this helps.......
Rick
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OBDII
May 14, 2010 18:46:12 GMT -4
Post by 76jeep on May 14, 2010 18:46:12 GMT -4
change the spark plug . i had a ford pick up did the same thing with new plugs in it . i had 14km on then .
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Enos
Hardcore
Founding Member
Posts: 8,513
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OBDII
May 14, 2010 19:11:24 GMT -4
Post by Enos on May 14, 2010 19:11:24 GMT -4
.....you can try swapping injectors too I should have mentioned that, they swapped injectors on my car and the code followed it. Those were the steps in the service manual for them to follow.
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Big Willy
Jeeper
My idea of a symphony? Six pistons playing a tune my right foot tells it.
Posts: 1,510
|
OBDII
May 16, 2010 13:25:34 GMT -4
Post by Big Willy on May 16, 2010 13:25:34 GMT -4
What I ended up doing was erase the check engine light to see if it would come back on. Its been about 2 days and nothing. The light came on when I tromped it getting onto the #103. So maybe that was the cause in the first place. When it came on I noticed it flutter then came straight on when I floored it.
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