Johnny_Cracker

iTrader: (1)

I’m learning about the inductive ignition system used on our cars and understand it all fairly well except when it comes to ignitors/igniton modules.

When learning online about inductive ignitions the examples I saw all used breaker points. From these examples I assumed that we too used breaker points to interrupt the circuit and collapse the primary’s field inducing the secondary’s high voltage and trigger spark. This caused confusion when considering the role of the ignitors in our ignitions, as I saw no reason for them to be there.

So my question is do we use traditional points? Reading the FSM suggests that it’s a magnetic pickup of some kind and not a traditional breaker point system. Like a hybrid points/electronic ignition... I can see the role of the ignitors if that’s the case, as something needs to interpret the magnetic pickup sensor data and convert it into timing for the coil. In this case I assume that’s what the ignitor does.

A straight up explanation of what’s really happening in there (esp regarding the ignitors) would really clear things up for me, and maybe answer why J-109s cost so much. Explain it like you would a 5yr old, I don’t care just make it concise. I’ll get my highchair and bib in the meantime.

My only experience with distributors has been when I replaced the cap and rotor when I got the car. I’m more comfortable working on it now and am tempted to pull it using FSM guidance so I can stare at it’s guts for a while. My goal is to go DLIDFIS or 2GCDFIS at some point but want to fully understand what I’m doing, not just follow a tut…

t_g_farrell

iTrader: (1)

So you've basically got it about right. The 79 SAs used a tradition breaker point ignition but
from 80 on its an inductive mag pickup similar to what GM used in the 80s up thru the early
90s.

The only reason the Mazda ignitors are expensive is that they are one off designs for the
rotary engine and so do not enjoy the benefits of scale, say a GM 4 prong ignitor does in the
parts market. In fact theres very few manufacturers of the Mazda ignitors so they tend to
cost a lot! Its all supply and demand as they say.

The ignition on rotaries, even with the RX8, has always been the weak point for these cars. Not
sure why but I expect it has to do with costs of development and manufacturing.

Theres lots of ways to rework the ignition to use more readily available domestic parts that
also provide better spark. In my sig is a link to my version of a DFIS ignition using GM ignitors
and Ford TFI coils. Since you've mention DFIDFIS I assume you been reading about those as
well.

The 2GCDFIS is very easy to do and is better than stock but the coil can burn out ignitors
eventually even with the right ballast resistance. The traditional DFIDFIS as pioneered on the
boards by Jeff20B is an excellent system too.

j9fd3s

iTrader: (3)

yes instead of a mechanical switch, like the points, they switched to a magnetic pickup and transistor.

like T-G says, the J-109's are expensive, just because they were only used on the 81-85 Rx7's, GM probably makes more pickups in a month than Mazda made Rx7's between 81-85.

TheOdditie

iTrader: (1)

I switched over to T-G's ignition setup on my 7 for cheap. Its hard to find the GM modules you need, at least around here it is, because all of the yards are picked clean, but even going to the parts store and buying new ones, they are cheap. The Ford coils are pretty easy to get at a salvage yard, look for old Lincoln Town Cars, they are the easiest to grab.

Cookboy

iTrader: (10)

I'm a relative oaf when it comes to these things, but last week did the 2GCDFIS on my 85 s model. It is a noticeable and only took me 15 minutes improvement. I used the kentetsu easy wire method. And just bought 2 Chinese j-109's for the glovebox.
Mitsubishi OE# J007X00471

Johnny_Cracker

iTrader: (1)

Awesome guys, thanks for clarifying that for me... I've been reading the TT thread and between your info and the TT thread I'm a lot more confident.

t_g thanks for the link and clarifying why j-109s are crazy money. I'm hoping to hit the local wrecker today and snag a 2G coil. If they have any FBs I'll be sure to scrounge for j-109s. They aren't sure what they're inventory is but assured me they have "a few" 7s.

Thanks again!

Jeff20B

iTrader: (13)

If you really want to try 2GCDFIS, get a GM HEI ignitor. It'lls burn out a J-109 in a month.

If you choose DLIDFIS, which I would personally, J-109 ignitors work great but GM HEI ignitors are easier and cheaper to find.

Johnny_Cracker

iTrader: (1)

Thanks Jeff.. I know you're the man regarding this so I'll take your advice and go DLIDFIS instead.

It'll save me burning up J-109s and manipulating my schedule around the local wrecker's banker's hours

Any preference on coils??

Jeff20B

iTrader: (13)

Stock Diamond coils cork fine. They are what came with the car and were designed to work with the J-109s and vice-versa. But these coils also work with GM HEIs.

If you decide to get more into it, get stronger aftermarket coils for the GM HEIs. They can handle more amps than J-109s.

J-109 can handle 3 amps each before going into current-limit mode.
GM HEI can handle 5 to 6 amps each.

Johnny_Cracker

iTrader: (1)

Awesome thanks for the info!!!