IEX Dwell change

Includes MoTeC CDIs, Ignition Expanders

IEX Dwell change

Postby ddahlgren on Sat May 12, 2012 3:12 am

Is there any fix for the IEX Denso verion dwell stretch from what is in the dwell table? Why can't I get what I ask for? Specifically a D585 AC Delco coil that will self discharge if dwelled wrong.
Dave :?
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Re: IEX Dwell change

Postby stevieturbo on Sat May 12, 2012 6:40 am

ddahlgren wrote:Is there any fix for the IEX Denso verion dwell stretch from what is in the dwell table? Why can't I get what I ask for? Specifically a D585 AC Delco coil that will self discharge if dwelled wrong.
Dave :?


Can you explain that in English ?

What exactly is the problem ?
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Re: IEX Dwell change

Postby ddahlgren on Sat May 12, 2012 9:49 pm

I have been told by Motec USA that the IEX adds dwell time beyond what is in the dwell table at engine speeds below 400 rpm. Some ignitions will self discharge if the dwell is too long to prevent them from burning up, the AC Delco D585 happens to be one of them though a very good in all other respects a very good inexpensive coil. I really don't want to run wasted spark and fire 2 coils at a time and eliminate the expander. I have an M800 but only 6 ignition outputs. That leaves me the choice of firing 2 coils at a time or use the IEX. I am not comfortable firing 2 coils at a time to be candid. It is a very expensive engine car combination with very few spare parts available if at all, Aston Martin 6 liter twin cam V8 in a vintage GTP car. I have not put a scope on the coil output of the IEX at cranking but will do this weekend. Since the change from distributor to coil near plug the car is very hard to start as it is kicking back on the starter from the coils self discharging. I am looking for a solution to theis 'feature'.
Dave
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Re: IEX Dwell change

Postby Scott@FP on Sun May 13, 2012 6:57 am

Set up the dwell table voltage x RPM? Its a 20x11 capable table. RPM breakpoints 0, 400, 401, etc. 400 RPM and below adjust to compensate. Always remember the v3 axis channels are only limited by your imagination, you could even set up the run RPM to 401, and use Run Time as an axis in the dwell table, Run Times above zero can revert to a normal voltage comp, run times equal to zero can have a different value.
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Re: IEX Dwell change

Postby stevieturbo on Sun May 13, 2012 8:32 pm

ddahlgren wrote:I have been told by Motec USA that the IEX adds dwell time beyond what is in the dwell table at engine speeds below 400 rpm. Some ignitions will self discharge if the dwell is too long to prevent them from burning up, the AC Delco D585 happens to be one of them though a very good in all other respects a very good inexpensive coil. I really don't want to run wasted spark and fire 2 coils at a time and eliminate the expander. I have an M800 but only 6 ignition outputs. That leaves me the choice of firing 2 coils at a time or use the IEX. I am not comfortable firing 2 coils at a time to be candid. It is a very expensive engine car combination with very few spare parts available if at all, Aston Martin 6 liter twin cam V8 in a vintage GTP car. I have not put a scope on the coil output of the IEX at cranking but will do this weekend. Since the change from distributor to coil near plug the car is very hard to start as it is kicking back on the starter from the coils self discharging. I am looking for a solution to theis 'feature'.
Dave


What sort of rpm's do you intend to use ? I run a non Motec supercharged LS2 using the factory LS1 coils. I fire mine as wasted spark and have no issues. Highest rpm I'd see is 7300rpm
Been using them for a few years now. I usually run my dwell at 4.5ms, although even at 3ms it seems to work just fine.
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Re: IEX Dwell change

Postby SprinterTRD on Mon May 14, 2012 1:27 pm

Dwell extension is done by the ECU as well.

The length of the dwell ectension is to some extent dependant on the REF/SYNC mode.

The IEX can be modified to only give a 7.5ms dwell time however the timing is delayed during cranking so CRIP can only be done after the engine has started.

If you need the IEX modified you will need to return the IEX through a MoTeC dealer listed on the website.
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Re: IEX Dwell change

Postby ddahlgren on Mon May 14, 2012 8:34 pm

SprinterTRD wrote:Dwell extension is done by the ECU as well.

The length of the dwell ectension is to some extent dependant on the REF/SYNC mode.

The IEX can be modified to only give a 7.5ms dwell time however the timing is delayed during cranking so CRIP can only be done after the engine has started.

If you need the IEX modified you will need to return the IEX through a MoTeC dealer listed on the website.


Problem is a D585 will self discharge at 5.8 or so ms, 7.5 is a non player. I have the Denso modified one and am a dealer in USA quite familiar with the mod. Problem is I sold about 50 of the coils before this feature showed up. Previously used LS1 D580 coils that have much less power. So a return on 3000 dollars worth of coils and then buy 3000 more in coils to replace them is a real financial bind.

It is running dual edge mode as it is near impossible to change trigger positions they are built into the damper and are where they are sort of thing. I am at a loss to understand the whole loss of dwell control below 400 rpm.

Is the dwell extension a function of the initial programed dwell so the suggested dwell vs rpm vs battery volts table could work or does it just default to 7.5 ms with the IEX? If that is the case then playing with it on the bech with a scope is a bit pointless.

Dave
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