AuthorTopic: V8i misfire  (Read 741 times)

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Offline Friskydisco

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V8i misfire
« on: January 22, 2008, 12:15:25 »
Hi, new on here and not so good with the V8 engine.
I have changed the following (or recently changed) - plugs/leads/coil/dizzy cap/battery, my disco starts ok but does seem to have a missfire, is there any other areas to check, i think cam ok head gasket ok, could it be an injector or maybe a faulty plug/lead.
My plans are to remove 1 lead at a time and use this to locate a problem cylinder and also make sure that all the leads etc are doing what they should and be where they should, i take it the no1 cylinder is rh front and firing order is 1,8,4,3,6,5,7,2.
Exhaust to downpipe gasket nearside bank blowing but should not affect it like this, was told it could be the dizzy itself, what you think? :-k.

Cheers.

Offline Evilgoat

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Re: V8i misfire
« Reply #1 on: January 22, 2008, 15:07:38 »
Couple of people seem to have had coil problems of late and seems there may be some dodgey rotor arms about from a certain national automotive chain too.

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Offline Krull

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Re: V8i misfire
« Reply #2 on: January 22, 2008, 15:16:58 »
i have herd that the b**tpart rotor arms sometimes fail. i also heard that the colour of the cap can make a difference. land rover do black and some replacements are blue or mite be the other way round. i will ask my son.
« Last Edit: January 22, 2008, 15:19:07 by Krull »
If it broke, I wasn't there.

Offline Evilgoat

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Re: V8i misfire
« Reply #3 on: January 22, 2008, 15:38:00 »
Wrong chain. Had a duff one on the vit (burnt out) Audi had one break up wrecking the hall sender and cap. Mates V6 Paj had one let go too.

I must confess the the activities of the UK governments for the past couple of years have been watched with frank admiration and amazement by Lord Vetinari. Outright theft as a policy had never occured to him.

-- (Terry Pratchett, alt.fan.pratchett)

EX HK Police Mitsubishi Pajero 2.8TD
Audi S2 Avant 360bhp
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Offline burgerman

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Re: V8i misfire
« Reply #4 on: January 22, 2008, 15:45:51 »
replacement caps are generally blue, I did runa blue cap for sometime with no problems, but changed it as matter of course and the "new "one packed up quite soon afterwards, Also the routing of the ht leads is important, did you have a misfire before you changed the parts ?? You could put everything back as std (old bits) and then change 1 item at a time, also swap the plugs around in the holes and see if that changes where the misfire is, and the same goes for the leads where possible,
I did have the inners of a dizzy pack up, but that didnot run at all, I think pulling of i ht lead at a time to locate the cylinder at fault, would be a good base move, ( use proper plastic pliers for this) and go from there, keep us updated

  P.S have also had  a blocked injector ( twice) this causes a misfire also,
TD5 with a few Tweaks ;o)
a bit more fuel friendly than the V8

Offline Friskydisco

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Re: V8i misfire
« Reply #5 on: January 22, 2008, 16:46:21 »
Thanks for that, the dizzy cap, leads and plugs were done just before i got it, know the bloke well and no reason to suspect issues but i will check everything on sunday, cheers.

Offline Range Rover Blues

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Re: V8i misfire
« Reply #6 on: January 23, 2008, 14:19:04 »
Rotor arms, if it's got a rivet in the middle of it then it's probably s***, even if it came from Halrfrauds like mine did.

Dizzy cap, take it off and look at the terminals inside.  They should be starting to burn slightly (they are white metal) but if you see one that is less burned then that one missfires. That's what my LSE was doing, and trust me, with a V8 you won't notice 1 cylinder going down unless it's under load.

If you intend to try and find out which cylinder is missing with the engine at idle, try unplugging the injectors, but you need to do 2 before you really notice the revs drop.

Another test is to check the temp of the exhaust stub next to the head, to see if one is cold.

Plugs want to be BP6ES or equivelent in a 9.35:1 CR engine.

Check the leads don't light up, indicating internal damage or cross arcing, check also the lead routing, it's critical.

Do a compression test.

Does your exhaust 'chugg' or is it a smooth tone?

Are you loosing any coolant?
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Offline Friskydisco

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Re: V8i misfire
« Reply #7 on: January 27, 2008, 16:01:34 »
Not had chance to have a look yet but plenty to go on there, cheers.

Offline gtomo2

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Re: V8i misfire
« Reply #8 on: January 27, 2008, 16:22:31 »
Just sorted a misfire out on mine. It was the tourqe head screw thet holds the vacum housing on the dissy was loose. just tighten it up and all is well. so have a look at that  and see if the vacum housing moves . As that will cause a misfire
Mr Graeme Thomas (tomo)
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