2 ms·

Cars tend to fail more disastrously now, but less often. If my coil back goes I am SOL. There's a reason they tell you to keep one in the trunk. The difference

Cars tend to fail more disastrously now, but less often. If my coil back goes I am SOL. There's a reason they tell you to keep one in the trunk. The difference to that and a cap+rotor is, a cap and rotor is about 12 bucks and can be done on the side of the road without tools, and that cap and rotor fits about 50 million 4 cylinders manufactured in the last 50 years, and tends to degrade more gracefully. On the flip side, cars now tend to run more efficiently till they break fully and go into limp mode or won't run - a lot less tuneups and tweaking, no adjusting the valves and carb as the car ages

bayindirh 5y ago
I've lost coil twice. Once was during driving. I lost a single cylinder, check engine light turned on. I was able to drive up to 70Km/h without my check engine light start blinking (means "you can melt your catalytic convertor, exhaust is too fuel rich, reduce throttle!"). Went to my service guy, he put down his tea on my engine, replaced it and his tea was half (~10 minutes). Also put in a new set of plug wires since my set was ~18 years old and gone hard at that point. I went to office, lost 30-40 minutes at most. The second one happened when the car was at park, at night. Started it in the morning, it was running off, so went to service. Same story. 70Km/h speed, 10 minute change, sans the cables this time. Newer cars tend to use one per plug. It's just a disconnect, pop-off, push in, plug, go. 2-3 minutes at most.
- calvinmorrison 5y ago
  yeah, this is actually something we are looking at for the Saab T5 engine series. It uses an integrated coil pack for all the cylinders, which in turn means, a failure of one is a failure of all. I know some of the tuners have switched to using more normal coil pack setups, but unfortunately the T5 system is pretty unique so its not a thing that can be easily hot swapped. One interesting tidbit is the coil packs run a bit of current over the plug when it's not sparking to measure ionization to determine engine conditions (i think mostly knock)
  - bayindirh 5y ago
    > It uses an integrated coil pack for all the cylinders, which in turn means, a failure of one is a failure of all. That’s interesting. My coil pack is also integrated, but it’s designed to fail independently. Maybe it’s the design of the coil, but not an inherent shortcoming of the system itself. > One interesting tidbit is the coil packs run a bit of current over the plug when it's not sparking to measure ionization to determine engine conditions (i think mostly knock) Didn’t know that. I knew that engine knock was measured with vibration sensors, crank position relative to other things and engine output measurements via load sensors (irregularity), but ionization measurement is new to me. Have any sources, so I can read more?
    - calvinmorrison 5y ago
      I think it was basically since Saab was fairly early to the coil pack game, these "Direct Ignition Cassettes" was in production in 88... Yeah... no standard knock sensor, which is the normal way to do things, but it's much improved because a regular knock sensor on a 900 can't really tell, what cylinder is knocking (and no cylinder behaves the same, regardless of what you do), so on a distributed 900 with the Bosch systems, it'll hold boost back or (with ezk) retard knocking for a few full cycles. With ionization it can determine -which- cylinder is knocking and adjust timing and fuel on that one specifically Here's a good article https://eeuroparts.com/blog/tech-corner-saab-trionic-and-ionization-sensing/ https://eeuroparts.com/blog/tech-corner-saab-trionic-and-ion...
      - bayindirh 5y ago
        That was an awesome read, thank you!

bayindirh 5y ago

I've lost coil twice. Once was during driving. I lost a single cylinder, check engine light turned on. I was able to drive up to 70Km/h without my check engine light start blinking (means "you can melt your catalytic convertor, exhaust is too fuel rich, reduce throttle!"). Went to my service guy, he put down his tea on my engine, replaced it and his tea was half (~10 minutes). Also put in a new set of plug wires since my set was ~18 years old and gone hard at that point. I went to office, lost 30-40 minutes at most. The second one happened when the car was at park, at night. Started it in the morning, it was running off, so went to service. Same story. 70Km/h speed, 10 minute change, sans the cables this time. Newer cars tend to use one per plug. It's just a disconnect, pop-off, push in, plug, go. 2-3 minutes at most.

calvinmorrison 5y ago
yeah, this is actually something we are looking at for the Saab T5 engine series. It uses an integrated coil pack for all the cylinders, which in turn means, a failure of one is a failure of all. I know some of the tuners have switched to using more normal coil pack setups, but unfortunately the T5 system is pretty unique so its not a thing that can be easily hot swapped. One interesting tidbit is the coil packs run a bit of current over the plug when it's not sparking to measure ionization to determine engine conditions (i think mostly knock)
- bayindirh 5y ago
  > It uses an integrated coil pack for all the cylinders, which in turn means, a failure of one is a failure of all. That’s interesting. My coil pack is also integrated, but it’s designed to fail independently. Maybe it’s the design of the coil, but not an inherent shortcoming of the system itself. > One interesting tidbit is the coil packs run a bit of current over the plug when it's not sparking to measure ionization to determine engine conditions (i think mostly knock) Didn’t know that. I knew that engine knock was measured with vibration sensors, crank position relative to other things and engine output measurements via load sensors (irregularity), but ionization measurement is new to me. Have any sources, so I can read more?
  - calvinmorrison 5y ago
    I think it was basically since Saab was fairly early to the coil pack game, these "Direct Ignition Cassettes" was in production in 88... Yeah... no standard knock sensor, which is the normal way to do things, but it's much improved because a regular knock sensor on a 900 can't really tell, what cylinder is knocking (and no cylinder behaves the same, regardless of what you do), so on a distributed 900 with the Bosch systems, it'll hold boost back or (with ezk) retard knocking for a few full cycles. With ionization it can determine -which- cylinder is knocking and adjust timing and fuel on that one specifically Here's a good article https://eeuroparts.com/blog/tech-corner-saab-trionic-and-ionization-sensing/ https://eeuroparts.com/blog/tech-corner-saab-trionic-and-ion...
    - bayindirh 5y ago
      That was an awesome read, thank you!