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Link ignitors/HED715 coils and dwell times

Stu Jones

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Hi guys, 

Hopefully have answered my own question/found the issue but after a second opinion please.

Im running a 4age turbo setup with a G4+ storm with direct ignition via 2x 3 channel Link ignitors (1x spare channel each) and 4x HEC715 coils.  This is a new setup and im still running the car in (~70kms so far) but have a nice safe tune to 6psi and 8000rpm.  Pretty conservative timing in the positive pressure areas so plenty more to go.

From the outset the car has felt a little 'soft' from 6000rpm and above which I just put down to not alot of timing but after a recent trip to Meremere to make sure everything was working ok I've noticed that there is actually really soft miss from 6000rpm.  I've started simple with fault finding and replaced the leads and plugs (BKR7E) with a new spare set without change which in my mind points the finger at either the coils/ignitors or something in the config.

My question is does anyone know what are the dwell/voltage capabilities of the Link ignitors and the HEC715 coils?

I've checked the logs from the road tune/Meremere and the system voltage is pretty much spot on and varies very little away from 14.15volts.  The coils are fed from a 40amp relay so I don't think its a feed issue.  I've read the coils do have a known issue of spark jump across the terminals but only for much higher load scenarios (can be solved with terminal boots anyway). In my case I'm fairly certain the dwell times are the cause but I'm yet to adjust these up until I've done a bit more research.  My hunch is that the current dwell time for operating voltage is too low and that's causing the issue - its currently set at 2.2ms from 6000rpm and reduces to 2.0ms at 8000rpm. Im thinking somewhere around 3 - 3.5ms is probably better.

Unfortunately I don't have any data sheets for the ignitors or coils as to their capabilities.  I've found some info online for the coils and it looks like they'll handle quite a bit of dwell time. Is there anyone who has run these coils before that would have a dwell table I could have a look at?  Or if anyone has any other ideas.  I'd assume the link ignitors can handle pretty much anything thrown at them?

Thanks in advance


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That sounds like a very interesting setup you've got there, unfortunately, I don't have any practical or working experience with the components of the inductive discharge ignition system you are using to give direct feedback as you requested. However, I am a little curious as to how the engine is breathing in the noted engine speed range. Can you give any feedback with respect to this?

I find inductive discharge ignition systems quite interesting, they're extremely effective is matched correctly both from a hardware and software perspective. Capacitive discharge ignition systems are pretty straight forward as far as available spark energy goes, but the inductive takes a little bit more to have it spot on.

Thanks for sharing with the online Link ECU community, cheers!

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Went for another log session yesterday.  Changed the dwell up a bit and its has seemed to smooth things out alittle bit but hasn't solved the issue.  I got thinking about the triggering and then in the new log from yesterday I've noticed im getting a few trig1 errors which seem to occur in sync with the miss.  I currently have trig1 filtering at level 1 so will increase this to 2 and also see if I can keep the HT leads further away from the CAS. Fingers crossed this will help.

Will update again once I've tried it.

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