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[Webby the Bear]

Hi guys, been playing about with my new multi-meter  it's so cute, its only a little bit bigger than my Nationwide card reader!!!!

Aaaaaaaanyhoo.....

Got some spare leads and I did resistance checks on them. These are the readings PER 300mm (30cm)............

lead:
1 - 5970 ohms
2 - 4808 ohms
3 - 5390 ohms
4 - 3916 ohms
5 - 5116 ohms
6 - 4007 ohms

Do these look ok? I'm thinking leads 4 and 6 are a bit low 

With these resistance checks I can hear MarksDTM telling me I shouldn't rely on resistance readings. and as he told me to think a bit more (something I sometimes have difficulty with  ) I also checked that the only other check you can do is to see how pliable the wire is and whether theres any obvious breaks in the insulation. now it just so happens that lead 4 isn't pliable at all and looks definitely bent from where it was clearly moulded in to shape by the vx dealer. so from a diagnostic point of view i'd say that was bad, coupled with the low resistance reading (think theyre meant to be around 5000 ohms per 30cm roughly  )

Anyway, thanks for listening and any advice you can give me would be great so I can pick the best leads and get my car running again

[Kevin Wood]

It's true. Resistance readings aren't that conclusive, really.. and I wouldn't worry about any of those. You're talking about putting at least 40000 Volts across the leads plus the plugs. a few K ohms of resistance is pretty insignificant. It's the insulation that matters, and you can't easily measure that.

[Webby the Bear]

It's true. Resistance readings aren't that conclusive, really.. and I wouldn't worry about any of those. You're talking about putting at least 40000 Volts across the leads plus the plugs. a few K ohms of resistance is pretty insignificant. It's the insulation that matters, and you can't easily measure that.

Thanks Kev,

Well thinking more about it, I had a hard time actually getting a reading on some. I wiggle the lead about and on some of the leads the resistance stays the same. on some it drops and I struggle to get a reading. so i'm presuming that I should take this in to consiederation when assessing whether theyre good leads.

they look fine. no insulation breaks, scarring etc. but but ones from europarts are bendy and flexible. the ones on their are stiff and not very  malleable. this I trust should be taken in to consideration?

sorry for long winded reply but im just trying to get my head around it 

[zirk]

Just forget testing testing HT leads for good or bad with the Ohm's range on a DVM, its a non starter, as Kevin says they act totally different when trying to pass high voltage to the spark plugs.

[the alarming man]

the one's for my disco have actualy got a 5 ohm impedance built in to them for some reason....??

[Webby the Bear]

Went out to try and sort the car today but only managed to replace breather o rings cos the weather is just rubbish. sorted that but there a.) still sounds like theirs a vac leak somewhere and b.) still a bad misfire 

anyway.... in my pursuit for omega happiness i'm swapping out the leads for known good ones and replacing the disspac if needed (I have a spare). however, i'm just wondering if in my effort to relocate the disspac I've over stretched the connecting wire (did look kinda stretched) and that's causing the misfire.

what test can I perform with my multi meter to make sure the current going to the disspac is correct . if you could also tell me in baby terms how to hook my multi meter up to the connector to test this that would be sweet.

 

thanjs

[martin42]

if you want to sort it out 2moro want me to pop over and have a look 

[Webby the Bear]

if you want to sort it out 2moro want me to pop over and have a look 

mate that would be wonderful. ill send a pm 

[dbdb]

Sometimes if you have a hammer every problem can look like a nail!  I thought your 2nd video showed an air leak, what with the spray speeding up the engine yet being nowhere near the air intake?

Defo can't test the HT leads much with a multimeter, you would need a megger tester AKA loop tester AKA insulation tester, that puts 500V down the circuit and tests for leaks.  But anyway that's for 220V circuits not the 12,000V to 45,000V on an HT lead. Some will do more though, seen a nice 5,000V Chinese one for £120.  Or 10,000V for £3,000 Mine only does 500V