Ls430 misfire problem P0300 P0301 P0303 P0305 P0306
12-10-22, 02:24 PM
#1
1st Gear
Thread Starter
Ls430 misfire problem P0300 P0301 P0303 P0305 P0306
Hello ,
Ls430 DTC P0300 P0301 P0303 P0305 P0306.
Changed spark plugs , ignition coils - problem coming back (old spark plugs and coils looks bad). Also changed sealing for top covers and plugs.
it could be problem with O2 sensor or camshaft sensor?
Ls430 DTC P0300 P0301 P0303 P0305 P0306.
Changed spark plugs , ignition coils - problem coming back (old spark plugs and coils looks bad). Also changed sealing for top covers and plugs.
it could be problem with O2 sensor or camshaft sensor?
Last edited by dbrz; 12-10-22 at 02:27 PM.
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Shebeer (02-12-23)
12-10-22, 04:45 PM
#2
Pole Position
Hello,
What coils did you use? The ones marketed as OEM on eBay and Amazon are likely counterfeit and of dubious origins, I would suggest looking for low mileage, used OEM options, those coils were pretty common, so it shouldn't be a problem.
Start by using this tool to check the spark strength, and while at it, run the engine for a little bit and then take the spark plug out in one of the misfiring cylinders to see if it will have fuel on it, which will indicate that the injector is working. You can also try swapping the coils around to see if the code will shift to another cylinder, indicating a problem with the coil itself.
If there is no spark, and swapping the coils doesn't change anything, try checking the wiring. From Left to Right - Pin 1 is Constant 12V supply, Pin 2 is a Return Signal that the spark was fired, Pin 3 is a Signal from the ECU and Pin 4 is Constant Ground. Pins 1 and 4 can be checked with a simple Test Light, while to check the ECU signal you will need an LED bulb, the signals are too short for the regular incandescent one.
Hope this helps and best of luck!
What coils did you use? The ones marketed as OEM on eBay and Amazon are likely counterfeit and of dubious origins, I would suggest looking for low mileage, used OEM options, those coils were pretty common, so it shouldn't be a problem.
Start by using this tool to check the spark strength, and while at it, run the engine for a little bit and then take the spark plug out in one of the misfiring cylinders to see if it will have fuel on it, which will indicate that the injector is working. You can also try swapping the coils around to see if the code will shift to another cylinder, indicating a problem with the coil itself.
If there is no spark, and swapping the coils doesn't change anything, try checking the wiring. From Left to Right - Pin 1 is Constant 12V supply, Pin 2 is a Return Signal that the spark was fired, Pin 3 is a Signal from the ECU and Pin 4 is Constant Ground. Pins 1 and 4 can be checked with a simple Test Light, while to check the ECU signal you will need an LED bulb, the signals are too short for the regular incandescent one.
Hope this helps and best of luck!
02-11-23, 11:19 AM
#3
One potential cause is the carbon buildup on the cylinder intake ports. If your LS430 fuel system is only direct injection, then there will be carbon buildup; which affects the operation of those ports. If your LS has a dual injection system (port & direct injection), you can rule out this problem.
My 2006 GS with 120K miles has a direct-injection-only fuel system. And I would get a P0306 (cyl 6 misfire) during startup after about two weeks of sitting idle in the cold weather. The misfire would go away after 30 seconds of running. It's nerve-wracking for sure. And I don't know why the misfire is only with cylinder 6. A new spark plug and a new coil didn't solve the problem.
Besides the potential misfire problem, the carbon deposit also reduces horsepower and fuel economy. One solution is to get rid of the carbon deposit on those ports, a $1000 value proposition! It's too expensive so my solution is to not idle the car for more than a couple of days.
My 2006 GS with 120K miles has a direct-injection-only fuel system. And I would get a P0306 (cyl 6 misfire) during startup after about two weeks of sitting idle in the cold weather. The misfire would go away after 30 seconds of running. It's nerve-wracking for sure. And I don't know why the misfire is only with cylinder 6. A new spark plug and a new coil didn't solve the problem.
Besides the potential misfire problem, the carbon deposit also reduces horsepower and fuel economy. One solution is to get rid of the carbon deposit on those ports, a $1000 value proposition! It's too expensive so my solution is to not idle the car for more than a couple of days.
02-12-23, 12:25 AM
#4
Try to change purge valve
02-16-23, 05:30 PM
#5
One potential cause is the carbon buildup on the cylinder intake ports. If your LS430 fuel system is only direct injection, then there will be carbon buildup; which affects the operation of those ports. If your LS has a dual injection system (port & direct injection), you can rule out this problem.
My 2006 GS with 120K miles has a direct-injection-only fuel system. And I would get a P0306 (cyl 6 misfire) during startup after about two weeks of sitting idle in the cold weather. The misfire would go away after 30 seconds of running. It's nerve-wracking for sure. And I don't know why the misfire is only with cylinder 6. A new spark plug and a new coil didn't solve the problem.
Besides the potential misfire problem, the carbon deposit also reduces horsepower and fuel economy. One solution is to get rid of the carbon deposit on those ports, a $1000 value proposition! It's too expensive so my solution is to not idle the car for more than a couple of days.
My 2006 GS with 120K miles has a direct-injection-only fuel system. And I would get a P0306 (cyl 6 misfire) during startup after about two weeks of sitting idle in the cold weather. The misfire would go away after 30 seconds of running. It's nerve-wracking for sure. And I don't know why the misfire is only with cylinder 6. A new spark plug and a new coil didn't solve the problem.
Besides the potential misfire problem, the carbon deposit also reduces horsepower and fuel economy. One solution is to get rid of the carbon deposit on those ports, a $1000 value proposition! It's too expensive so my solution is to not idle the car for more than a couple of days.
03-02-24, 04:39 PM
#7
Moderator
DTC P0300 other than P30X often means that the fire timing is OFF. I'd simply check the timing belt removing the cover.
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