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2002-2005 Range Rover MkIII / L322
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170 Posts
Discussion Starter #1
Hi all my car is now pretty much tip top - lean rich reading on both banks are within +-5 drives lovely with no particular issues. Starts nice etc

only problem I have is a misfire from lots of cylinders at idle - always has it but it’s barely noticeable it doesn’t log a fault and I only know it’s missing because of the misfirecounter on my scanner. Maf, o2 etc all brand new. I have an lpg conversionit does it on petrol and lpg so that rules out the fuel system, it has new plugs so all I could think was coils, but is this the behaviour of failing coils on the 4.2?

cheers
 

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2006-2009 Range Rover MkIII / L322
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117 Posts
I've had 2 coils fail so far and both times they set a code for misfires and went into limited power mode.. The misfire from lots of cylinders you describe is not setting any code?
 

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Registered
2006-2009 Range Rover MkIII / L322
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610 Posts
Hi all my car is now pretty much tip top - lean rich reading on both banks are within +-5 drives lovely with no particular issues. Starts nice etc

only problem I have is a misfire from lots of cylinders at idle - always has it but it’s barely noticeable it doesn’t log a fault and I only know it’s missing because of the misfirecounter on my scanner. Maf, o2 etc all brand new. I have an lpg conversionit does it on petrol and lpg so that rules out the fuel system, it has new plugs so all I could think was coils, but is this the behaviour of failing coils on the 4.2?

cheers
Hi dan.
If your problem cylinder related you have to feel misfires. Swap the coils first. A bad coil can cause + fuel trims like 8-10.
Plugs are new it can be injectors.
But first step to deadline starts always with cold misfires. On our engine mostly ends with low compression on 7th or 8th cylinders.
Check compression if everything is fine look at the injectors.
Injector cleaner not solve my problem I replaced injector on 5th cylinder.
Not working injector cause misfires and effects fuel trims. Mine was +20-22
 

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2002-2005 Range Rover MkIII / L322
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170 Posts
Discussion Starter #4
Compression is a bit low but still over 130 all cylinders - I am just getting misfires occasionally at idle on all cylinders. It’s running a bit rich at idle now. I have lpg as well and it does the same so I can rule out anything in the fuel system... coils or something else?
 

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Registered
2006-2009 Range Rover MkIII / L322
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610 Posts
Compression is a bit low but still over 130 all cylinders - I am just getting misfires occasionally at idle on all cylinders. It’s running a bit rich at idle now. I have lpg as well and it does the same so I can rule out anything in the fuel system... coils or something else?
Maybe valves?
Exhaust valves mostly.
If you have rough idle on cold start but everything is fine after warm up or on warm start it shows a mechanical issue in my opinion.
Bad coils mostly shows a blinking check engine light under load.
 

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2002-2005 Range Rover MkIII / L322
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170 Posts
Discussion Starter #6
No I have a good start always hot cold whatever the marginally rough idle is Oren there when warm too
 
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