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2006-2009 Range Rover Sport
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Discussion Starter #1
I have a 2006 Range Rover Sport Supercharged with 80k miles. It has a newer battery and alternator. Wife was driving it when it quit on her. I took it for diagnosis at a shop that specializes in land rover and was told that bad coil(s) caused the fuses (F4 and/or F6) to blow and create a no start symptom. When the fuse was replaced it would start up and run on the old OE coils for about 20 minutes or until it was put under load, at which point it would idle rough and blow the fuse(s). I replaced all the coils with the cheap coils from local parts store. Those cheapo coils actually started burning up and catching fire so I pulled those all out and put the stock coils back in. Never got the new cheap coils running long enough to where it would blow the fuse again though. Any ideas? I am not getting a miss on any specific cylinder during the warm up - it will just all the sudden start missing and blow the fuse(s). Could it possibly be one coil acting up and causing the entire issue? Would quality OEM coils be my solution?

Any help is much appreciated!! Thank you!
 

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2006-2009 Range Rover Sport
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Discussion Starter #2
Still at this - checked battery voltage and it's @ 12.5V with engine off and peaks around 14V when its running. Any other ideas to diagnose this before buying oem coils? And also, anyone have a recommendation for quality coils? Thanks.
 

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I hope your problem is a bad ground and not as I've experienced.

I had very similar symptoms to yours, the car would cough and splutter under load and often (But not always) die, usually at the worst possible time like pulling away from a junction in fast flowing traffic. I replaced the coils and it cured the issue for about 4 weeks before it got even worse. I reverted back to the original coils and it improved over the replacement set so I knew it was the coils again. Fitted another set which lasted another 6 months before the problem returned. This time I was advised that if I replaced the coils, I should replace the plugs too. I did this and it ran fine for another 6 months before it coughed yet again. I did a lot of research before finding a company online who explained what the actual issue was. It turned out to be the ECU which caused the coils to burn out and then damage the plugs. They also explained that the ECU problem could have been down to me running the original damaged coils for to long before replacing them and after that, there was no alternative but to replace the ECU, Coils and plugs. V expensive! So it was my fault for running the car for about 4 weeks with the original blown coils. I was kicking myself for a long time over this.
 

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2006-2009 Range Rover Sport
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Discussion Starter #5
Arby - thanks for sharing. I will have to investigate grounds. Need to find an accurate diagram of where the earth points are on the RRS. Does anyone have a source? That would be convenient if it was just cleaning those points up.

m3bobby - sounds like a nightmare. If my scenario is like yours, I should go ahead and replace the coils with quality oem coils and quality plugs and hope the ecu isn't damaged.

Does anyone have a recommendation for coils and plugs for RRSS? Thank you all.
 

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2006-2009 Range Rover Sport
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I find it very hard to believe that it is bad coils or plugs. Coils don't all of a sudden go bad in a bunch. Sounds like a problem that is common to all the coils like grounding . maybe capacitor.
 

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I can only assume it only takes 1 or 2 bad coils to drag down the ECU which in turn destroys the other coils. All I can say is that a replacement ECU, coils and plugs fixed my problem for good.

Would a temp jump lead between engine and chasis help eliminate a bad ground? Could be worth a shot.
 

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2006-2009 Range Rover Sport
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Discussion Starter #8
Thanks m3bobby - I tried your suggestion of a temp jump lead from engine to the negative terminal on battery and did not get any change in voltage at the battery - this leads me to believe there isnt much voltage drop in the earth points?

After checking around I found the tsb on the auxiliary cooling pump: http://www.rrsport.co.uk/gallery/albums/userpics/14362/coolant pumpLTB00041NAS2 (1).pdf

When replaced the auxiliary cooling pump fuse (F4, 25A) it blows immediately when the engine is fired up. The coil fuse (F6, 15A) will not blow until the engine is warmed up and under load. At this point it will misfire briefly, throw misfire codes for every cylinder, and the coil fuse (F6) blows. If the cooling pump is disconnected at the electrical connector the cooling pump fuse (F4) does not blow with engine running. This leads me to believe the cooling pump is bad, based on TSB and age of the vehicle. I checked the wiring at the connector and mine appears to be correct - black wire on the left, brown/purple wire on the right when looking up at it from below.
Could the fact that the auxiliary cooling pump is not operating (due to blown fuse) cause my misfire symptom and then blow the coil fuse or are these completely separate issues?
Thank you all for your help.
 

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2006-2009 Range Rover Sport
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Discussion Starter #9
I did look closer and the aux cooling pump was wired backwards - fixed the wiring but didn't replace the pump - the aux cooling pump fuse does not blow now. Went for a drive and I am still getting hesitation and what feels like misfire after warm up when the engine is put under load, mainly when accelerating from a stop. If I give it WOT it will smooth out the hesitation once I get to higher RPM but will hesitate and feel like a misfire as soon as I slow to a stop and accelerate again. It will idle and rev pretty smoothly in park or neutral. I am back to believing it is an ignition coil issue, only because I am not getting a reduced engine power warning on the dash. Thoughts? Anyone? Thanks.
 

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2006-2009 Range Rover Sport
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Discussion Starter #10
Anyone have suggestions for coils - My factory coils are Denso 099700-0711. I called Land Rover and they gave me part number 4744015. I have found many aftermarket coils with this part number. Who makes the OEM coil? Any help is much appreciate! Thanks.
 
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