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2006-2009 Range Rover MkIII / L322
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Discussion Starter · #1 ·
2006 Range Rover Supercharged 4.2 with 64,000 miles. I just purchased the vehicle and during the test drive I noticed a slight hunting at idle. I had the 60,000 mile service performed by Land Rover and also had them perform a diagnostic check and all was clear. In driving since this (less than 400 miles) the hunting continues and have twice received the Check Engine Light driven consistently by P0302 (Cylinder #2 Misfire) and P0316 (Engine Misfire on 1st 1000 Revisions). Following clearing of the CEL I have been dumping codes following each drive and will occoasionally pick up a P0302/P0316 but no CEL.

Have looked through a lot of the information on the forum and am still struggling to identify a root cause. To date have performed the following:
- Repalced the coil on #2 cylinder (no issue noted on disassembly)
- Replaced #2 Spark Plug (no staining or water intrusion noted)
- Just put in a dose of the RR recommended Fuel Injector Cleaner (BGK 44) and have run about a quarter tank through the vehicle.


The issue is not consistent and will occur randomly both Hot or Cold but is mainly present when Cold. The Freeze Frame data I have collected indicates the issue driving the CEL is occurring always when cold. Freeze Frame data information captured is as follows:

Fuel Sys 1 CL
Fuel Sys 2 CL
Calc Load (%) 31.37
ECT (F) 95
STFT B1(%) 3.13
LTFT B1(%) 11.72
STFT B2(%) 0.0
LTFT B2(%) 11.72
Fuel Pressure (psi) 34.37
MAP (inHG) 11.22
Eng RPM 705
Veh Speed 0
Spark Adv Degrees 30
IAT Temperature 46
MAF (ib/min) .97
TPS 16.08


Any insight would be greatly appreciated.
 

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Misfires that stay on one particular cylinder on this are usually ignition, but since that's been replaced, lets start with the idle and go from there.

Give this a read, for an interim fix for the idle hunt, follow the instructions about spray cleaner into the intake while running, the rest can be handled once that is fixed, and ruled out as a possible cause for the misfire.

http://www.rangerovers.net/forum/9-...-can-someone-help-throttle-body-location.html

Also, is the MIL flashing, or does it just turn on and then you find the 302 fault?

And always good to have the freeze frame, however, it really doesn't mean much on this engine, as everything is variable. Even the >10% long term trims might only be at idle, which would be completely different then if they are that way under a load.
 

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2006-2009 Range Rover MkIII / L322
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Discussion Starter · #3 ·
Appreciate the response - the MIL does not flash. Also the idle hunting is sporadic and does not always trigger a code even when it does occur.
 

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2006-2009 Range Rover MkIII / L322
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Have you replaced your thermostat? I have same year and engine and my tstat was getting hung up and causing engine to run on cool side. Replaced it and now works perfect. Just wondering if you are getting a misfire when cold due to low operating temp.
 

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2006-2009 Range Rover MkIII / L322
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Discussion Starter · #5 ·
Good point - the only question I would have is it is showing that the codes are in 1st 1000 revolutions which implies it is at ambient. If thermostat failed open I would assume the code would come up after the first 1000 revolutions. When I get a chance I am going to try the Throttle Body spray option referenced but appreciate the thermostat option.
 

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Discussion Starter · #6 ·
Update - I have completed a throttle body cleaning, fuel injector flush, and thermostat replacement. I also had a smoke test done and a small leak was found on a fitting on the inteake manifold which required a gasket to be replaced. As of right now the idle hunting is nearly gone but there is still a very slight fluctuation. Reset all of the codes an after a couple of days am still throwing a CEL on P0302/P0316. Any insight as to where to look next would be greatly appreciated.
 

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2006-2009 Range Rover MkIII / L322
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Discussion Starter · #7 ·
Appreciate some help - have done all I can think of to include a cylunder pressure test. #2 registered ~150 and 2 others I tested came in at 175 - could the 25 lb difference be triggering the P0302/P0316?? The FF data for every occurrence is still showing it immediately after starting. Idle hunt has been repaired and the vehicle runs great. Could it be a faulty fuel injector??
 

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Have you wet tested No 2 cylinder ? IE squirt some engine oil in that cylinder and then re-check check the compression ? If it shows normal after doing the above you have a piston ring or bore issue, if it doesn't change it's a valve or head gasket problem. All easily fixed but problematic.

Chris.
 

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Discussion Starter · #9 ·
Squirted oil in - no pressure change - so a valve or head gasket. If head gasket would I not see something in oil or loss of coolant.
 

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Discussion Starter · #10 ·
Been one week - no CEL - running well. In a nutshell - seems a combination of things finally did the trick - injector flush, fix pinhole leak on boot to SC, coil, and plug. So far - So good
 
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