Re: Exasperated by stuttering SP250... all suggestions welcome!
Posted: Tue Jun 04, 2019 12:50 pm
Well, I'm back.... grubby and weary... but triumphant!
Much further tinkering and elimination of components left the finger of blame pointing squarely at the electronic ignition unit, as I had begun to suspect..... Consequently I went through the faff of reverting to an original points and condenser set up - not an easy swap as it required another distributor base plate, it's original having been modified to take an optical electronic ignition set up in the past....
Anyway, with points back in, the advance weights checked and the distributor back together it fired right up and sounded.... fabulous! A road test along the exact same route as all previous tests resulted in NO ill-running and it runs like a dream.... at long last... yay!!
When I think of the years it has taken to finally eliminate this.... and good old points were the solution all along....
You may well wonder why on earth it has taken so long and why the finger of blame didn't immediately point to the electronic ignition from the outset? Because it wasn't changed directly from points. If it had been, I think the problem would have been immediately obvious. The electronic ignition was fitted to replace a different electronic ignition system that was itself failing.... We knew the first Lumenition system had failed and it presented with very similar symptoms but cooked coils as well. The chances of replacing a failing electronic ignition system with a brand new, but faulty, different brand electronic ignition system that produced very similar symptoms must be in the millions to one. As a result, the true source of the running issues was well disguised and we began to suspect that there was something else amiss beyond the original failing Lumenition system. Being unreliable and untrustworthy, the Dart wasn't used very much so it never made it to the top of the job list to undertake a thorough end-to-end investigation..... Knowing that points couldn't simply be refitted without sourcing another top plate for the distributor and the fact that the latest failed electronic ignition presented no symptoms when cold and continued to fire a big fat spark all along hasn't helped.
Still, it's been an interesting journey and I am most appreciative of all the input every one of the contributors to this thread has taken the trouble to provide - it has been enormously helpful and many lessons have been learned, not least in failure analysis and the importance or revisiting the last component touched FIRST....!
Much further tinkering and elimination of components left the finger of blame pointing squarely at the electronic ignition unit, as I had begun to suspect..... Consequently I went through the faff of reverting to an original points and condenser set up - not an easy swap as it required another distributor base plate, it's original having been modified to take an optical electronic ignition set up in the past....
Anyway, with points back in, the advance weights checked and the distributor back together it fired right up and sounded.... fabulous! A road test along the exact same route as all previous tests resulted in NO ill-running and it runs like a dream.... at long last... yay!!
When I think of the years it has taken to finally eliminate this.... and good old points were the solution all along....
You may well wonder why on earth it has taken so long and why the finger of blame didn't immediately point to the electronic ignition from the outset? Because it wasn't changed directly from points. If it had been, I think the problem would have been immediately obvious. The electronic ignition was fitted to replace a different electronic ignition system that was itself failing.... We knew the first Lumenition system had failed and it presented with very similar symptoms but cooked coils as well. The chances of replacing a failing electronic ignition system with a brand new, but faulty, different brand electronic ignition system that produced very similar symptoms must be in the millions to one. As a result, the true source of the running issues was well disguised and we began to suspect that there was something else amiss beyond the original failing Lumenition system. Being unreliable and untrustworthy, the Dart wasn't used very much so it never made it to the top of the job list to undertake a thorough end-to-end investigation..... Knowing that points couldn't simply be refitted without sourcing another top plate for the distributor and the fact that the latest failed electronic ignition presented no symptoms when cold and continued to fire a big fat spark all along hasn't helped.
Still, it's been an interesting journey and I am most appreciative of all the input every one of the contributors to this thread has taken the trouble to provide - it has been enormously helpful and many lessons have been learned, not least in failure analysis and the importance or revisiting the last component touched FIRST....!