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help me please 4.0 V8 hunting


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Hello, my 2003 year discovery 2 has 4.0 V8 engine. The car has hunting. At high RPM the receipt of engine check is flashing and is loosing power. I have changed spark plugs, spark plug wires,ignition coils, injectors, fipl,detonation sensor but it is not fixed.when I plug in OBD it writes sometimes about second barrel and sometimes about seventh barrel. It shows problem of differrent barrel every time.Sparks are getting black. Plese let me know if anyone can give an advice. In my country noone could find out the reason

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By barrels do you mean cylinders? basically the container the pistons go up and down in?

If the spark plugs plugs are getting black that would imply and over fueling issue and as it is a 2003 it will be fuel injected. perhaps a kind moderator would move this thread to the international board as this is a V8 issue more of the guys will see it. 

Unfortunately I don't know how the fuel mixture is determined but the first thing I would look at is the air filter, is it clean or the air flow metre is it working properly and is the air flow clear?

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Just now, BogMonster said:

Moved as suggested - there aren't that many V8 Discoverys in the UK membership so it's more likely to get an answer in International

Thanks BM my thinking was that it covers all V8's not just Discos and there are many on here that are doing mods using injected V8's

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Sounds like too much fuel, and RV8's don't run well with fouled spark plugs either.

I would check/change the coolant temperature sensor (the 2-pin one NOT the one for the gauge) near the thermostat housing, if that fails it could be a few other things which are less easy / more expensive - the AFM, or a stuck fuel pressure regulator.

There is an EFI troubleshooting manual in the technical archive - it's for the earlier EFI system but most of the checks are the same process/idea if not exactly the same hardware.


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