3.4L V6 DIS with a "spark cut" feature?

[Fallen2603]

I'm planning on turbocharging a 3.4L V6 to dump into my '90 Camaro RS, and I would like to have a "spark cut" feature to help prevent detonation. I'm planning on running a MegaSquirt EMS and possibly a MSD Ignition Controller.

Now, I've been told that there is no way to run a "spark cut" feature with the 3.4L V6 DIS, even if I use the MegaSquirt and MSD Ignition Controller. My source isn't 100% sure about this, though.

I'm just wondering if someone on here could tell me 100% whether or not a "spark cut" feature can be run with the 3.4L V6 DIS.

THANKS!
~ Jeremy

[robertisaar]

here's why you can't cut spark entirely(though you could reduce it greatly to be sure detonation doesn't happen).

the ICM has a certain amount of advance built into it. because of this, you can NEVER get timing to go below this, only above.(or at least that's the way i remember it being explained)

also: guess what happens with true spark cut systems that don't cut fuel at the same time? when the spark is allowed to happen, all of the raw fuel that didn't get ignited in the combustion chamber like it was supposed to? it's in a BIG stream all the way from the exhaust ports to the tip of your muffler. that flame happens and there's a good chance something is going to either blow up or permanant damage will happen to your exhaust components.

[Superdave]

hook the shift light output up to a relay that controls power to the ICM.. then set the shift light to turn on at a certain RPM.


Wait, can't you un-plug the ECM feedback/tach (big) plug from an ICM and the engine will stay running just at the 9 degrees base advance? Maybe one could break that connection at a certain RPM.

[Azrael]

I remember seeing a discussion on this at megasquirt's forum. I think it ended with the fuel-cut option being safest even under boosted applications.

[robertisaar]

hook the shift light output up to a relay that controls power to the ICM.. then set the shift light to turn on at a certain RPM.

you know.....

[Fallen2603]

robertisaar
Okay, so a TRUE "spark cut" feature would be bad, right? I just want to make sure that if I were to over-rev the engine, and it hits the fuel cut-off, that I don't suffer detonation. It sounds like the Ignition Control Module is the way to go. As long as I won't have enough spark in an ultra-lean setting, such as what I described above, and I'll still be kept out of the catastrophic explosion scenario, I'll be happy.

Superdave
What do you mean by "shift light output"? I'll admit, I don't know much about what all is included with an engine management system...

Azrael
So, this has been brought up regarding MegaSquirt systems before? Sorry, kinda new to this site. Mostly on thirdgen.org...

Anyways, sounds like the Ignition Control Module will be able to keep most of the bad things from happening. Guess I don't need a true "spark cut" feature...

[issues]

I remember seeing a discussion on this at megasquirt's forum. I think it ended with the fuel-cut option being safest even under boosted applications.

If you run the ms extra code you can get both fuel cut and spark cut.

[Fallen2603]

Sooo...if I used the MegaSquirt with the "extra code", I wouldn't actually need the MSD Ignition Control Module? Or would I?

I'm more used to carb's than dealing with, let alone MODIFYING, EFI systems...LOL!

[Azrael]

Found the thread I was talking about earlier. It's a long read but lots of food for thought.

http://www.msefi.com/viewtopic.php?f=31&t=32875

[issues]

No you don't have to use the MSD unless you want to run it.

[Fallen2603]

What advantages would there be to running the MSD ICM in tandem with the MegaSquirt EMS? Any?

[Fallen2603]

Okay, as of now, after reading the thread that Azrael sent me, I'm thinking that I'll go with BOTH the MSD ICM and the MegaSquirt EMS. That way, if I'm right, I'll be able to control BOTH fuel and spark and retard, or cut, them simultaneously to avoid most of the bad/DISASTEROUS situations.

DISCLAIMER: If I'm wrong, please, tell me. I won't be the guy tuning the MegaSquirt or MSD ICM on this engine, obviously, as I have no experience doing so. I'm just trying to plan out how to best make this set-up as "Idiot-Proof" as possible.

Oh, and thanks for all your help!

[Fallen2603]

BUMP

Any other input on this?