Hybrid_From_Hell Posted June 24, 2006 Share Posted June 24, 2006 Got the axle back together (still need to do brakes and Oils) etc So, I thought I'd tackle the mysterious misfire. It happened straight after a HUGE Misfire when it was cold over fueeling and "Kicked Back", splitting the plenum to AFM Hose wide open Anyway............. started it .............ran it out on the drive. Fuel Pressure - OK Air Leaks - NONE OK (Hose Replaced) and then worked my way through a load of things - No difference. Hmmmm Replaced the original Ign system with rotor arm cap and V8 Leads - er NO So, its not the EDIS MegaJolt then B) WTF is it I checked the entire system with the diagnostic manual, changed AFM Resistor pack, Checked Therootle Pot, gap on buterfly, fuel level ( ok) NOTHING Sat an thought and pondered. In desperation I changed the NGK BP7RES (1 month new) for the old ones Ran sweet as a nut So, happy but puzzled. Why can / would a misfire destroy a new plug ?? Nige Quote Link to comment Share on other sites More sharing options...
western Posted June 24, 2006 Share Posted June 24, 2006 This NGK sparkplug info & plug part number decoder might help Quote Link to comment Share on other sites More sharing options...
Hybrid_From_Hell Posted June 24, 2006 Author Share Posted June 24, 2006 This NGK sparkplug info & plug part number decoder might help Cheers Ralph Went had a look (that link should be IMHO in the tech archive !) and found this DETONATION : The spark plug's worst enemy! (Besides fouling) Can break insulators or break off ground electrodes Pre-ignition most often leads to detonation Plug tip temperatures can spike to over 3000°F during the combustion process (in a racing engine) Most frequently caused by hot spots in the combustion chamber. Hot spots will allow the air/fuel mixture to pre-ignite. As the piston is being forced upward by mechanical action of the connecting rod, the pre-ignited explosion will try to force the piston downward. If the piston can't go up (because of the force of the premature explosion) and it can't go down (because of the upward mo-tion of the connecting rod), the piston will rattle from side to side. The resulting shock wave causes an audible pinging sound. This is detonation. Most of the damage than an engine sustains when "detonating" is from excessive heat The spark plug is damaged by both the elevated temperatures and the accompanying shock wave, or concussion Hmmmmmmmmmmmmmmm Nige Quote Link to comment Share on other sites More sharing options...
western Posted June 24, 2006 Share Posted June 24, 2006 Wasn't sure if those links would help, but you seem to have found a reason for your duff plugs, I'll copy the links into the Tekkie Archive. hth Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted June 24, 2006 Share Posted June 24, 2006 It's amazing the difference plugs can make to the V8, I guess insulation damage is a Bad Thing when you've got a spark as big as Nige's setup. Quote Link to comment Share on other sites More sharing options...
Hybrid_From_Hell Posted June 24, 2006 Author Share Posted June 24, 2006 Oh yeah Tell me about it I had a "Fiddle" ( ) a while back, basically played with the plug leads on the MegaJolted V8 whilst it was on tickover, done this loads of times when it was on the original plugs and ign system - just pull a plug lead off and "Brace" yerself for the small jolt etc, to check for a misfire,. Did this on the MegaJolted V8 a while back, the 1st plug lead I pulled off gave me a "Belt" strong enough to make me go and sit on me stool in the workshop for 10 mins, didn't even switch the engine off I felt so bad, mate did it for me (between hysterics - GIT) Me hand up to me wrist was 101% numb .....and I felt like I was going to 'Bark' big timey Have greater respect for the syetem since Nige Quote Link to comment Share on other sites More sharing options...
LR90 Posted June 24, 2006 Share Posted June 24, 2006 Ooh, that made me cry laughing Nige Quote Link to comment Share on other sites More sharing options...
Hybrid_From_Hell Posted June 24, 2006 Author Share Posted June 24, 2006 Yippe Doooo Made me almost cry too, but for very different reasons I will NEVER do that again,................. it is also I found slighty later on ........... a fair cure for Constipation Nige Quote Link to comment Share on other sites More sharing options...
LR90 Posted June 24, 2006 Share Posted June 24, 2006 I learnt at an early age that when presented with a broken plug, broken in a way thay exposes three wonderfuly shiney and interresting looking brass heads of the resp pins, that the careful arrangement of your fingers to enable you to simultaneously make contact with all three at the same time is not recommended either. Very exciting but not in the way I'd anticpiated Quote Link to comment Share on other sites More sharing options...
western Posted June 24, 2006 Share Posted June 24, 2006 (edited) Hey Nige, God !! your bloomin' lucky ever thought why you nick named it 'MEGAJOLT' cos you do now Edited June 24, 2006 by western Quote Link to comment Share on other sites More sharing options...
honitonhobbit Posted June 24, 2006 Share Posted June 24, 2006 My Dad introduced me to magnetos when I was about 5. "here you go son, just hold onto this wire whilst I wind this little armature!" Needless to say, I have passed this lesson on over the years - I have a nice ickel Ducelier Magneto from a petrol Fergie stashed away for those special times Quote Link to comment Share on other sites More sharing options...
Hybrid_From_Hell Posted June 24, 2006 Author Share Posted June 24, 2006 here you go son, just hold onto this wire whilst I wind this little armature Nige Quote Link to comment Share on other sites More sharing options...
bill van snorkle Posted June 24, 2006 Share Posted June 24, 2006 one evening a couple of years ago an annebriated Kombi van driver ran into a power pole outside my house. I rushed outside to find the driver slumped unconcious over the steering wheel ,obscuring the ignition key, and foot jambed hard on the throttle. There was petrol everywhere, the engine was screaming at full revs and the only thing I could think of was to open the engine hatch and reef the distributor cap off. Well in the couple of seconds it took to do that I must have received a few hundred high voltage belts that still makes me wince when I think about it. Quote Link to comment Share on other sites More sharing options...
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