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1995-2002 Range Rover P38A
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99 Posts
Discussion Starter #1
Hi

Recently changed the spark leads as one was broken and i didn't know how old they were. Also changed the plugs as they also looked old, again no idea on service history in that respect.

Plugs one and four were all black and nasty, the others were fine. I've got good compression on all 8, so I'm assuming the related coil pack is on its way out, is that a correct assumption or could it be anything else?

I'm getting a p1319 code, but i think that's a red herring and related to lpg switchover. No other codes to suggest a misfire or injector problems

Thanks
 

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On a Thor, you have two coil packs, each containing two coils. One drives cylinders 1 & 6 while the other drives 4 & 7 so it seems unlikely to be coils. Black plugs would suggest a rich mixture so it's possible that you have dribbling injectors on those two so they are dual fuelling when running on LPG. If running on LPG you need to be changing plugs every 10-15,000 miles anyway.
 

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1995-2002 Range Rover P38A
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99 Posts
Discussion Starter #3
Ah yes, you're right. I must have miss read the order somewhere.

In still edging on the electrical side at the moment as when i connect a timing light I'm not getting regular sparks and it seems to run the same on gas and petrol.

Unless the injectors are leaking enough to stop the spark? The plus don't seem to be that wet though, just black.
 

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1995-2002 Range Rover P38A
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359 Posts
When running on LPG the engine runs a lot better when you make the gap on the spark plug 0.5mm.
 

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Registered
1995-2002 Range Rover P38A
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359 Posts
Ah yes, you're right. I must have miss read the order somewhere.

In still edging on the electrical side at the moment as when i connect a timing light I'm not getting regular sparks and it seems to run the same on gas and petrol.

Unless the injectors are leaking enough to stop the spark? The plus don't seem to be that wet though, just black.
When there leaks enough petrol in the combustion chamber while running on LPG, it just runs like crap while idling, say like running on 6 cylinders, and at about 1800rpm it runs fine again.

I owned a car with a 5.0 V8 running on LPG from what 2 injectors weren't closed off when it ran on LPG.
 

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1995-2002 Range Rover P38A
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99 Posts
Discussion Starter #6
Cheers guys. I gapped the new plugs to .7mm but happy to try .5mm.

the symptoms i get are regular pops on anything other than gentle acceleration. It runs exactly the same on petrol and lpg and didn't get any better further through the rev range.

I'm not entirely sure if the pops are down the exhaust or back through the intake. It does seem to idle fine though. I'm assuming it's not a MAF issue as that would present on all cylinders?

My guess is unburnt fuel being ignited in the exhaust.

I'm not driving it in this state other than test runs when i change something as i don't want to do any damage anything.

Thanks
 

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1995-2002 Range Rover P38A
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99 Posts
Discussion Starter #7
Having thought a bit longer about it and assuming it's not a coil issue then i suppose it has to be leaking injectors that are shorting the plug.

Is it possible to test myself? Or is that something for someone with special equipment?
 

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1995-2002 Range Rover Classic
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1,413 Posts
do a cylinder leak test and or remove your rocker covers and watch the rockers for full open and close function, this tests the cam for worn out lobes, the other option is to remove the intake manifold and top gasket and physically look at the cam lobes for wear.

while covers are removed check for broken valve springs, your worn cam and or broken valve springs may be causing combustion leak and at idle which may cause little to no rough idle, but off idle as pressure increases it sound like a misfire or the "pop" you mentioned above.
 

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1995-2002 Range Rover P38A
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99 Posts
Discussion Starter #9
I recently replaced the head gaskets so i got to see the cams and valve gear, both of which seem ok. It was running fine before i took the heads off and all plugs were clear.

I've just done a compression test and all 8 seemed good and even.

The only other outstanding engine issue i have is the temp doesn't get above above 62c even though I've taken the thermostat out and tested it. I've poured water into the housing and there's no leaks when it's closed, also put it in a pan of water and it's opening at the right time. Also pressure treated the coolant system and all seems fine there so far
 

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1995-2002 Range Rover P38A
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Discussion Starter #10
Just to add, the temp sensor does appear to be working properly
 
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