Decaying spark - any pointers?
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Decaying spark - any pointers?
I have been running the ignition upgrade as outlined here for quite a while now without any problems, but i now have a headscratching problem.....
I have a good fat spark on start up and tickover and for normal pottering, but the harder the engine revs, the weaker the spark gets until it breaks down and the engine starts to miss. It will keep going but is just not happy and having had a spark tester on it while revving you can see the spark get weaker and weaker as the revs rise higher and higher.... anyone got any ideas what could be causing this breakdown? So far i have changed the ignition amp for a known good one and fiddled about swapping components, but nothing i have swapped has made a significant difference. It seems that the breakdown is in the HT side, as the injection seems to keep working fine and this is taking its signal off the LT side, but any thoughts from you guys are welcome.
I have a good fat spark on start up and tickover and for normal pottering, but the harder the engine revs, the weaker the spark gets until it breaks down and the engine starts to miss. It will keep going but is just not happy and having had a spark tester on it while revving you can see the spark get weaker and weaker as the revs rise higher and higher.... anyone got any ideas what could be causing this breakdown? So far i have changed the ignition amp for a known good one and fiddled about swapping components, but nothing i have swapped has made a significant difference. It seems that the breakdown is in the HT side, as the injection seems to keep working fine and this is taking its signal off the LT side, but any thoughts from you guys are welcome.
you tried another coil???
Regards Tony C (COOPS)
MS2 V3.57 Ecu mapable efi and wasted spark ignition.
Procharger D1SC supercharger and Cossie RS500 Intercooler @ 14psi of Boost. 416 RWHP, (boost leak)
Forged 4.8 V8 kitted out with the dogs Cajones of parts.
Sponsored by: www.v8performanceparts.co.uk, www.interpart.biz, www.caprisport.com & www.baileyperformance.co.uk
MS2 V3.57 Ecu mapable efi and wasted spark ignition.
Procharger D1SC supercharger and Cossie RS500 Intercooler @ 14psi of Boost. 416 RWHP, (boost leak)
Forged 4.8 V8 kitted out with the dogs Cajones of parts.
Sponsored by: www.v8performanceparts.co.uk, www.interpart.biz, www.caprisport.com & www.baileyperformance.co.uk
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i would check the cap and rotor arm also,
i had a similar thing on my capri 4yrs ago,
i changed the cap and rotor arm and it was fine,
i had a similar thing on my capri 4yrs ago,
i changed the cap and rotor arm and it was fine,
Regards Tony C (COOPS)
MS2 V3.57 Ecu mapable efi and wasted spark ignition.
Procharger D1SC supercharger and Cossie RS500 Intercooler @ 14psi of Boost. 416 RWHP, (boost leak)
Forged 4.8 V8 kitted out with the dogs Cajones of parts.
Sponsored by: www.v8performanceparts.co.uk, www.interpart.biz, www.caprisport.com & www.baileyperformance.co.uk
MS2 V3.57 Ecu mapable efi and wasted spark ignition.
Procharger D1SC supercharger and Cossie RS500 Intercooler @ 14psi of Boost. 416 RWHP, (boost leak)
Forged 4.8 V8 kitted out with the dogs Cajones of parts.
Sponsored by: www.v8performanceparts.co.uk, www.interpart.biz, www.caprisport.com & www.baileyperformance.co.uk
might help if you listed what you had fiddled with and swapped around otherwise you could get a whole load of suggestions for what you have already done. The injection doesn't pick up on the HT side by the way so the fact your injection still works only means the coil is getting a trigger pulse not that its working properly.
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I did have similar problems last year, where the engine would rev to a certain speed and then miss until the engine would splutter,, if you tried driving it the problem only got worse,
If you have changed the Rotor arm and cap, and the engine was runnung fine, go back to the original pieces and see if that makes any diference, some of the rotor arms seem to be of an indiscrinate quality and can cause no end of problems, and this is also compounded by there being 2 different size rotor arms
If you have changed the Rotor arm and cap, and the engine was runnung fine, go back to the original pieces and see if that makes any diference, some of the rotor arms seem to be of an indiscrinate quality and can cause no end of problems, and this is also compounded by there being 2 different size rotor arms
THE SMOKING GNU
12.604 with an old boiler of a RV8 and no gas
WHY are there so many IANS on this site???????
12.604 with an old boiler of a RV8 and no gas
WHY are there so many IANS on this site???????
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I have tried rotor arms and caps, both genuine used Lucas items- same problem with the substitutes. Also tried swapping king lead and swapping a couple of individual spark plug leads (with spares) and it didnt seem to make any difference. I had always assumed this type of dizzy trigger was pretty reliable - from what i can see it is a microswitch tapped by the chopper on the dizzy shaft - is that right? Either way i wondered if there was anything any of you guys have had that has given similar problems before i start buying new stuff and eliminating by virtue of new components. I still think i am on the right lines with an HT failure of some form, it is just a matter of narrowing it down as i havent had a failure like this on any of motors before.
That is exactly it Ian, it will rev to say 4000rpm , then go no further no matter what throttle you use, wide, trailed, feathered etc. it just coughs and spits and wont go any higher.I did have similar problems last year, where the engine would rev to a certain speed and then miss until the engine would splutter,, if you tried driving it the problem only got worse,
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OK, i can't really see the pick up as the dizzy has the factory cover on so had guessed it was some sort of microswitch - what you say above makes more sense. I will check that there is an air gap.Hi,
If it's a 35DM8 or DLM8 the rotor shouldn't touch the pick up head. There should be an air gap.
Jim