rxAustin

The spark will always find the easiest path to ground. If the "easiest path" involves jumping through the coil body and across a substantial air gap to the strut tower, it sounds like the spark plug wires are bad (or not connected at the plug end). Also there may be flaws in the body of the coil, in which case the coils should be replaced. If you want to upgrade the coils, look into the DIS blaster coils that MSD designed for use with the DIS box. They are small but very powerful (just make sure they are properly grounded to the engine according to the instructions).

As for who I am - Jim from Rapid Transit in Wilmington, DE. I don't actually work there - I am sort of his tech guru.

Judge Ito

Jim I appreciate your time and help. I'll install the 8912 tomorrow and I'll reply with results. Thanks again.

Mx-7

Judge,
Did you finally get the trailing coil to work with 8912?

Judge Ito

Yes I did.. I noticed and felt a respectable hp increase with trailing working of the DIS 2. Faster acceleration and more responsive on low rpms. We are going to dyno soon. This is a 6 port streetport FC.

rxAustin

Judge,
Are you using the factory trailing coils?

Judge Ito

Jim I had to change over to the MSD digital coils.

RXTASY1

I am running a pair of Nology Powercores on my stock trailing coils with no problem.

rxAustin

Anything that doesn't require disconnecting the coils from the factory ignitor module should be fine (Powercore, HKS Twinpower, MSD Stacker, etc). All others will need the MSD 8912 adaptor.

Makes me wonder how many FC's are out there with 3 MSD's stuffed under the hood and only one of them actually firing???

rotarygod

iTrader: (1)

I was actually going to suggest that you change them. I found that the 2nd gen trailing coils didn't work when I tried to hook them up to my MSD on my direct fire conversion for my 1st gen as leading coils. I had to use the 2nd gen leading coils instead. They were easier to hook up anyways. Something about the reistance being wrong for the MSD to fire. Not quite sure. Just know it didn't work.

Judge Ito

Thats the first thing that came to mind. How many FC's running 3 MSDs with out the 8912 tach adapter for the trailing coils. Thanks again Jim.

Maxthe7man

Considering how many FC's have bad or misadjusted TPs's there are probably alot of bone stock fc's driving aroung without trailing ignition as well...
So Judge, are you using the stock coils on the leading still or did you change over the whole setup...Max

Mx-7

Judge,
I see...you swapped out the fc trailing coils for the msd digital coil, but did you use the tach adapter? Sorry for the ignorance...can ask you what the part number is for the msd digital coils???

Judge Ito

MSD DIS coil PN 8230 with the 8912 tach adapter and the msd DIS 2 ignition box. for trailing 1 and trailing 2. One box 2 coils and 1 tach adapter

Judge Ito

Max still using the stock coils for leading.

AJC13B

Why bother?

I only ever used T2 coils on my car and had no problems up to 28psi

Do you need different coils for n/a applications?

Judge Ito

Steve this was a consistent problem with second gen. Rx7 using the stock ecu.
If you go haltech or any other ems you will not find this problem.

rxAustin

The general consensus often is that trailing makes little difference powerwise, but maybe this is because the trailing ignition is inadequate. The plugs are tucked away behind the ~4mm "shoot holes", and the plugs have to fire through whatever leftover gasses didn't get cleared out from last time around. Trailing probably has higher demands for ignition that leading.
A killer ignition on the trailing might be worth something.

tcb100

Speakin' a coils, why are the T2 coils favored over the 3rd gen coils? I was under the impression that the 3rd gen ignition was pretty good.

rotarygod

iTrader: (1)

The trailing plugs actually make quite a bit of difference. Just by adjusting the leading/trailing split you can get some nice extra power. The trailing timing has a big effect on detonation. The closer the split the more likely the chance of detonation. The farther the split the less. This is why it is so nice to have seperate adjustments on an aftermarket ecu. They may not be in the greatest spot but they do something.

Xcessive

Just curius has anybody thought of the trailing coils with msds having 20-30deg spark duration having an effect. The reason I say this is, I run no split with 2 HVCs on lead and tried a msd box on trail and the motor at low speeds didnt like it. I know this is a diff setup than what you are talking about but when I went to factory coil on trail it ran good down low rpms. Just a question I guess on duration? Good or bad?

rxAustin

Actually on the trail you wind up with 40 degrees because each trail coil is like a 2 cylinder, so the MSD gets confused about how much time there is per revolution (ie how many firings per rev). It's possible, if you are using an 8 cyl box, to get 80 degrees out of it on the trail.
Also I will point out that the spark generated by an MSD doesn't actually last 20 degrees - there is a "window" of 20 degrees during which it will fire every millisecond. A little over 3000 RPM is where 20 degrees is less than a millisecond, so that where the multisparking stops. At this point you don't get 20 degrees worth - more like 6 depending on the coil. Also true of Crane, etc.

Xcessive - what was the symptom? (also what's you're setup? Distributor?)