Mounting the MSD Ignition System

[RSWiser]

My problem is definately a Rev Limiter.

When I hit exactly 3500 rpm wham it cuts out.

When I get back next week I will put the 6000 rpm limiter in and see what we have then.

Thanks for all the advice and help.

I do have to say that I did a great wiring job. The only wire you can see is a small black ground wire. Everything else is hidden. When I get it all cleaned up next week I will post some photos.

Thanks again.

[RSWiser]

Okay, I mounted the MSD Unit, New Vibration Coil and Tach adapter.

Could not get over 3500 RPM. Realized that I did not have any of the Rev Limit chips. Called Summit, they were shipped right out. Installed the 6000 RPM chip.

Go for a drive, cuts out at 3500 RPM. Installed 7000 RPM Chip, Cuts out at 3500 RPM.

Took car to local Porsche shop and they messed with it for a week and could not get it to work any better.

Removed the MSD system and re installed the CD. Car runs fine. Drove home all is good. Sending unit back to Summit.

No I just need to get it adjusted to meet emissions.

[RoninLB]

so far it sounds like a bad MSD box

if so it's the first new-ng one I've heard about.

And I don't trust any mfg CD box. I always carry a spare.

[RSWiser]

I think you might be right about a bad MSD box. When I got the box it was missing the rubber dampers for installation. Then I realized it was missing all of the Rev Limit chips.

So I am wondering if it was a return and they mistakenly re-sold it.

Oh well it is going back.

Rob

[Formerly Steve Wilkinson]

I'm not sure I understand why you think "a rev limiter" is the problem. (I have two MSD 6ALs, twin ignition, and my rev limiters are set at 7,300 and 7,500 rpm, for what it's worth--big-bore short-stroke engine.)

Anyway, I don't think the MSD boxes _require_ a rev limiter of any sort to work--it's an add-on. If you don't add the rev limiters, the thing will just let you rev to infinity...well, probably somewhat sooner. Doubtless you have a bad box, but I don't think whether or not it has a rev-limiter chip is the problem.

[campbellcj]

Originally Posted by Formerly Steve Wilkinson

I'm not sure I understand why you think "a rev limiter" is the problem. (I have two MSD 6ALs, twin ignition, and my rev limiters are set at 7,300 and 7,500 rpm, for what it's worth--big-bore short-stroke engine.)

Anyway, I don't think the MSD boxes _require_ a rev limiter of any sort to work--it's an add-on. If you don't add the rev limiters, the thing will just let you rev to infinity...well, probably somewhat sooner. Doubtless you have a bad box, but I don't think whether or not it has a rev-limiter chip is the problem.

Steve,

I am the new owner of a twin-plug setup with dual 6AL's as well, and I was curious about the rationale and results from the two different rev limiters versus setting both the same?

Cheers,

[Formerly Steve Wilkinson]

It's what Steve Weiner advised me to do, and I believe his thinking is that it'll give a "soft" limit with one bank of plugs dying at 7,300 and the rest cutting out just 200 rpm later, rather than a "bang" shutoff all at once.

Counter-thinking, for what it's worth, is that you don't want the engine running single-plug momentarily, especially under high rpm and load. But then I've never hit the rev limiter anyway; Rick Deman took it up to 7,000 several times when he dynoed the car, but that's the most it's ever done.

[JP911]

RSWiser-
Possible that the green and purple wires were swapped? The car will run with them like this, but it will have far too much advance. This could cause symptoms similar to what you describe.

[youfamissim]

I want the dude that cleaned up the green ride to do mine. Nice work. The Grand Canyon, Rachel Welch, your firstborn child, but few other things in life are as attractive as a cleaned up engine compartment.

[chamilun]

Originally Posted by JP911

RSWiser-
Possible that the green and purple wires were swapped? The car will run with them like this, but it will have far too much advance. This could cause symptoms similar to what you describe.

A nugget to add here:

Having just replaced my MSD box, and wiring it backwards, here are the symptoms I had with reversed purple/grn wires: very high idle (around 2k), runs with a huge miss, like the timing is way off (sort of is). (Removing the oil cap will still cause the car to run worse, and removing the O2 relay causes the car to die.)

[ninesixfour]

Originally Posted by RSWiser

I think you might be right about a bad MSD box. When I got the box it was missing the rubber dampers for installation. Then I realized it was missing all of the Rev Limit chips.

So I am wondering if it was a return and they mistakenly re-sold it.

Oh well it is going back.

Rob

Did you ever resolve this?