Irregular misfiring on 97 v8

[stuee]

Hi all,

As the title states I'm getting some irregular misfiring on the v8. I've checked the plugs and leads and they were in fairly good nick. The distributor cap and button were replaced not even 5000km ago too.

I say its irregular because its been coming and going but today it was happening all the way home from work. Giving it a hard rev under load appears to fix the problem then about 30 seconds later its back again. I'm wondering if there's some sort of common electrical fault that could cause this (maybe maf??).

Due to the misfiring it had real difficulty moving off the line from the traffic lights and left me thinking the thing was gonna die. Idle speed is dropping to about 500rpm and the misfiring is occurring all through the rev range. It makes me wonder if perhaps it isn't even a misfire problem but a fuel issue problem. Could also be something killing all spark but I'm just not sure.

I just want to have a shot at fixing the issue at home before I take it in to a workshop as I've got access to a spare car atm. So does anyone have any ideas on some simple diagnostic tests or what may be causing the problem.

If it helps when I was sorting out my stereo cabling I noticed that one of the factory relays was looking a bit suspect (cracked cover etc) but I didnt think much of it. I'm wondering if that maybe some electrical feed to the coil could be effected and causing an issue.

Cheers,

[disco@stu]

Just went through this same problem till the point it would not start, after much checking found out some info that it was the new rotor button that i had fitted (after market autobarn job) put in the proper Lucas unit and no more problems. No missing starts first bang

[stuee]

Just went through this same problem till the point it would not start, after much checking found out some info that it was the new rotor button that i had fitted (after market autobarn job) put in the proper Lucas unit and no more problems. No missing starts first bang

Well I guess I cant discount my nearly brand new rotor button then. Cheers mate that's something to add to the check list.

Did it show any signs of ware or was it just after replacement that it worked fine again?

[justinc]

I second the rotor button issue. I've had a 100% failure rate with non lucas rotor buttons. They may be exxy, but I have seen 20 yo 400K ones still in perfect working order.

JC

[stuee]

I second the rotor button issue. I've had a 100% failure rate with non lucas rotor buttons. They may be exxy, but I have seen 20 yo 400K ones still in perfect working order.

JC

Damn that's not cool. I only replaced the last one as it was listed in the service items in my manual :(

Is this a well known fact because I bought mine from a reputable parts supplier. Was cheap but didn't realize it wouldn't be cheerful.

What about the rotor housing? Is a non Lucas item usually naff too? Maybe I can upgrade to a high performance distributor :D Nice to dream :(

[justinc]

manual

Damn that's not cool. I only replaced the last one as it was listed in the service items in my manual :(

Is this a well known fact because I bought mine from a reputable parts supplier. Was cheap but didn't realize it wouldn't be cheerful.

What about the rotor housing? Is a non Lucas item usually naff too? Maybe I can upgrade to a high performance distributor :D Nice to dream :(

A Lucas rotor should set you back about $70 :eek: but believe me the tow truck will come to more than that:mad:
The Lucas caps are also way better quality, but over $100 retail IIRC :(

Have you still got the old one? or did you have to break it up to remove it?

JC

[rovercare]

A Lucas rotor should set you back about $70 :eek: but believe me the tow truck will come to more than that:mad:
The Lucas caps are also way better quality, but over $100 retail IIRC :(

Have you still got the old one? or did you have to break it up to remove it?

JC

Yep, the ONLY ****ing vehicle on earth, that must use genuine ignition components or else it all turns to poo:(

[camel_landy]

It's also worth noting that the V8 is also quite fussy about the condition of HT leads. Although a visual inspection show them to be OK, I have had problems like this which have been cured by new HT leads.

HTH

M

[stuee]

A Lucas rotor should set you back about $70 :eek: but believe me the tow truck will come to more than that:mad:
The Lucas caps are also way better quality, but over $100 retail IIRC :(

Have you still got the old one? or did you have to break it up to remove it?

JC

I have the old cap but only to show people the badly corroded points on it :(

The new cap looks pretty cheap too so it might be worthwhile upgrading that as well but jeeze that's an expensive exercise. I wonder what a high performance distributor is worth.

I wasn't that impressed with the leads either. I'll replace the cap and button first and see if that fixes it, if not then the leads.

Cheers people.

[MacMan]

+100 on the rotor issue.

I have NO IDEA why some of the parts suppliers persist in selling them. Total false economy to use them. It's also worth keeping your old genuine one in the back of the car as a spare.

[stuee]

+100 on the rotor issue.

I have NO IDEA why some of the parts suppliers persist in selling them. Total false economy to use them. It's also worth keeping your old genuine one in the back of the car as a spare.

If the rotor button is the cause I'll be asking the same thing when i go back to get a new one. Its a very well know parts supplier and the dude basically said this does the same job, but its a lot cheaper. Nothing about the fact that I'd have to replace it in under 6 months. Didn't think I'd have to research a rotor button replacement...

[stuee]

Well the new rotor arm was put in today and its as good as new!!

I swear it even runs even better than before the misfiring even raised its head.

For anyone interested here is the 6 month old after market rotor (not even 5000km's) and the new genuine Lucas product. $30 difference.

https://www.aulro.com/afvb/images/imported/2009/05/1124.jpg

[chazza]

Ironic isn't it? Years of Lucas products being bagged by just about everyone and now the only one that works is Lucas. ;)

My Disco has done 210 000km on the same Lucas rotor arm and I read about the dodgy ones on aulro :D

Cheers Charlie

[stuee]

Ironic isn't it? Years of Lucas products being bagged by just about everyone and now the only one that works is Lucas. ;)

My Disco has done 210 000km on the same Lucas rotor arm and I read about the dodgy ones on aulro :D

Cheers Charlie

I'm cut I threw my old one out. It only got replaced because it was a service item for that particular service. Otherwise it did 10 years of trouble free service.

[Boxer]

Yup, I'm with the other guys with the rotor button. Factory one is a must. Good leads and plugs help too (I've always found NGK to be good and Champion to be crap). Also helps to make sure all of your plugs (ALL) are getting good contact. I give mine a WD40 once over every now and then.

[Pierre]

AND.....

Check the operation of the vacuum advance mechanism by removing the line from the plenum and giving it a suck, observing the holding of vacuum and the movement of the reluctor plate assembly.

Why? I've serviced 2 cars in the last week, and both have failed vac adv units.

Source of reco ones? Performance Ignitions, Nunawading, Vic.

HTH

Pete

[V8Landy]

Had the same problem but i went through 2 sets before finding out to use genuine:(. No problems sense:D