Dwell time - how much to raise?

[tcode]

Hi,

after fixing some leaks on turbo to IC piping and adjusting the spring on a wastegate, finally having desired boost at higher revs. However, the engine starts to missfire badly @1,7bar of boost on more than 5,5k rpm. According to logs, fueling should be fine, so I'm thinking about raising of a dwell time. I'm running COP's (from a picture) and having absolutely no idea how much they can take. Currently, dwell time is set to 4ms, planning to add 1ms in steps of a 0,5ms. How much will be too much?

[rob@vems.co.uk]

Too much dwell will cause the coil temperature to rise - if it gets too hot it will burn out.
Try increasing your dwell 0.5ms but keep an eye on the coil temperature.  Do these coils have a driver built-in or are they straight coils driven by IGBTs?  If they are IGBT driven you could use an oscilloscope with current clamp to get some idea of the coil charge characteristics.

Saying this though I suspect that there might be an more of an issue with the coils themselves - they might just not be upto the job on a highly boosted engine, do you know of any other V40 engines that are running that much boost on stock coils?

Rob

[tcode]

Saying this though I suspect that there might be an more of an issue with the coils themselves - they might just not be upto the job on a highly boosted engine, do you know of any other V40 engines that are running that much boost on stock coils?

Rob

Hmm, those coils aren't stock on S/V40 engines, because stock ECU works with wasted spark. New coils are from Volvo 960 and I choose them only because they are bolt on and I saw them on one S40 running with stand alone (don't remember which one).

Oh well, I'll try increasing dwell time a bit and see what will happen .

[Andy P]

I was planning on running COPs too however I had access to 2 additional coils.

Standard Ignition system-




I was going to block off the HT lead connections with a rubber plug of some sort to prevent them from arcing onto the head.

A couple of people in the UK are still running the standard ignition (with remapped ECU's) running upto 1.9 bar and 400+bhp so I should hope I won't have any issues.

Andy P

[MWfire]

Andy P i think you must connect HT lead connections to head if you want to use 4 bobines.

http://www.aqtda.org/journal/vol2no1/img/DIS.gif

[Andy P]

Andy P i think you must connect HT lead connections to head if you want to use 4 bobines.

http://www.aqtda.org/journal/vol2no1/img/DIS.gif

So you think they should be grounded... I'll have to investigate when I get round to setting up my ignition.

Thanks for the heads up

Andy P

[rob@vems.co.uk]

That looks like the Evo4 coilpack on Beezy's Corrolla, they work nice with a short dwell time (2.5ms) on the Toyota 4A-GE engines, Team Dandism is using the Evo3 packs on his turboed one with no problems.

I'd stick with wasted spark myself...

[gunni]

Too much dwell will cause the coil temperature to rise - if it gets too hot it will burn out.
Try increasing your dwell 0.5ms but keep an eye on the coil temperature.  Do these coils have a driver built-in or are they straight coils driven by IGBTs?  If they are IGBT driven you could use an oscilloscope with current clamp to get some idea of the coil charge characteristics.

Saying this though I suspect that there might be an more of an issue with the coils themselves - they might just not be upto the job on a highly boosted engine, do you know of any other V40 engines that are running that much boost on stock coils?

Rob

Does anybody have a picture of this voltage clamp to reveal coil charge character.