Hi All,

Any advice on fine tuning my 4ltr V8. Just replaced all the spark plug leads and installed 8 brand new platium plugs due to a stuffed lead. Noticed that the platium plugs were also stuffed at 60,000. I thought they were good for 100,000km She runs on BP ultimate since I have had her. Any advice appreciated.

A 4.0 in WHAT car? ....a Disco or RR....What year?........I'm surprised you need Ultimate!!! (98 RON) .....They say, I think, UP TO 100,000 kms.....and unfortunately once you foul hem you can't successfully clean them!....Well, NOT supposed to, anyway, I think.

Sorry Byron,

I have a 2003 Disco. I always run BP Ultimate in all my cars as work is paying for it in some way. Whats an extra 10cents these days when I am paying $1.38 for unleaded. I think I also get a little extra milage with the ultimate (noticed it alot with sedans).I have only had her for 6 months so its all a learning curve.

Divemaster,
Could be coil pack, O2 sensor, theres no tuning these as there a closed loop circuit. Did u replace 1 lead or all 8? Make sure the leads arent touching anything..just some thoughts..

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Ex 89 RR Classic V8i, Ex 93 D1 200Tdi, Ex 97 D1 300Tdi, Ex 98 D1 V8i LS, Ex 01 D2 Td5
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Pete.

Hi sniegy,

Replaced all 8 leads and all 8 plugs. She isnt idling perfect like before. Its only just noticable. I am getting some ideas to look where to start. Thought the best time to fine tune would be with a new set of leads and plugs.

The 2003 Disco has a Thor engine with Motronic ECU( same as a BMW) and I think will be 9.35:1 so premium is required.( check next to the engine number)
According to the BMW blurb, you are only supposed to use the OE plug and leads, as the ECU reads the resistance on each firing and knows if the cylinder has missed, and if it has sends another spark. I do not know how important this is but the specialist who services my son's BMW uses the BMW plugs.

Perhaps you should open the wallet and take it to a specialist with a Rovercomor similar to see if any errors are logged in the ECU.
Poor idling could be a lot of things including plugs, leads, dirty injectors, dirty/sticking exhaust valves. Some will show up eg plugs/leads but mechanical problems such as valves will not.
These days its bloody hard to DIY.
Regards Philip A