I turn off the key but the engine keeps running.
This is a new problem after adding the MSD.

Key turns off the power, I know, because I can hear the fuel pump turn off.

It eventually shuts off after turning the key off/on/off/on or revving the motor with the key off.

What should I do?
Performance is spectacular, except gremlins are tenants.

KT

t dog


i know the answer....i have the hyfire thing right here....

brb with an answer.... i think you need the diode.... lemme check

Sounds like power is getting somewhere later than expected. Have you used any old wire, from say... the late 1800s?

Sorry, best I can do.


M

yep.... you need the diode! inline....

install diode/resistor in line with SWITCHED positve lead from msd box to igniton switch!

What diode?
Where me find?...grunt

KT

QUOTE (trekkor @ Feb 26 2005, 11:41 PM)

What diode? Where me find?...grunt KT

hmmm... you need a diode (lets current only flow one way)....

my cdi came with it.... hyfires are better

When all else fails, read instructions.

And, MSD includes the diode in their parts bag.

KT

If anyone has done this *fix*, please guide me through it.

MSD is kinda muscle car and not Porsche specific.( surprised? )

KT

My Hyfire did this last night. Only it was ANDY induced. I needed a switched power. So I figured I could use Andy's version of providing power from fuel pump. So I hooked up the jumper wire from the 4 prong FI to ground bingo 12V. However the dang thing wouldn't shut off.
So I moved the 12v source to share the black purple that used to go to the coil positive with the Compufire unit. Works great. Dark and rainy here today so I will clean up the engine compartment wiring and

oh yea my tach don't either. So I need one of them adapters. Wife is going to take the plastic pretty soon so I better get it quick.

I'm having the same problem,,,,,looks as if the diode goes on the D+ line that goes to the bulb in the charging circuit.....at least that's my answer....everything works AND shuts down when I pull THAT wire. Just no charging....

Mike,

I'm not too experience with the electrical stuff,

Can you please explain with a diagram?

Thanks

An internally regulated alternator has three wires....one to engine or chasis ground, one BIG RED one that goes to battery, then the D+ wire.....this is also known as the exciter, I think .....it has to go thru a powered bulb in the dash.

He, heh, big red one,,,,,exciter....heh, heh....sounds like a cheap porn movie dialogue....

This is one of TWO idjut lights....the other being the oil pressure light. When the ignition is turned on, lights are one.....when engine runs, the lights go out....

NOW, since the fuel pump and a few other items are on the +15 side of the ignition switch....there is a power feed back from the alternator that keeps the ignition switch open....it looks like the D+ line needs a little resistor to stop the feedback.

Mike,

Thanks for the reponse.
I was concern that my Electromotive would still be running
when I tried to kill the motor.
I have installed a toggle / kill switch - hot from the battery to the coil packs.
I should not experience any concerns right?
Have not started it yet, that's the reason for the last question.


Thank you

An on/off kill switch will work....but the diode will also work w/o having to do an extra step to switch anything off....

Mike,

Thank you

When your in LA , let me know, I owe you a COLD one

QUOTE (0396 @ Feb 27 2005, 07:24 AM)

Mike, Thank you When your in LA , let me know, I owe you a COLD one

Let's hope it works....kind of funny how more than a few of us have the same problem to deal with on the same weekend.....

I had some input from Captain Krusty and some others on the little winky board.....just gotta find a place that has a diode on a Sunday......or else wait.....

Another comment from the 911 board....Rich Herzog...he posts here too...

a diode...

the alternator charging current is powering the ignition, IIRC you
need a diode in the "switched +12" line. i don't recall which
direction it needs to point, but one way will work, and the other
won't...

a standard 1W epoxy rectifier diode from Radio Snack should do the
trick (this is not a critical application.

a diode is a check valve for electricity - flows only one way.

this is covered in MSD's instruction sheets, which are available
online in PDF form. i'll go dig up my 911 ignition folder if i need
to, but IIRC it's pretty easy to find the section where they talk
about the diode and how it's installed

The easiest place to put it is spliced into the alt. idiot light wire. or the red wire on the three plug connector from the altenator to the relay board.
Radio shack has them.

Since most of the Radio Crap guys are computer geeks w/o auto experience....what diode and what rating?

Trekkor has one but hasn't answered my email yet....prolly still in the rack after a hearty party last night....

Joe, the purple/black wire is the tach wire. It now needs to come off the MSD box and go to the tach directly.

The tach wire in the dash is a better looking prurple/black due to it's being protected from the elements for so long.

For my fuel pump key on power I'm using a wire off the stock relay board with no ground jumper. I use the front/right terminal on the F.I. socket. ( front right being closest to driver and engine ).

Mike, this is a bit odd. Same weekend.
So, which wire gets the diode? The D+ into the relay board or the keyed 12+ power to the MSD which is shown to be the original coil+ wire?

From the diagram on pg 8 of MSD manual it looks like the exciter wire needs to be diode protected so the small amont of voltage will will no longer activate the MSD which has it's own 12v constant power source.

KT

Yeah the D+ wire needs it...."I" need from YOU....the rating and/or a pic of it so I can get one from Radio Crap.....it also should be directional.....which way does it say to mount it in the stoopid book?

Pic coming...

Take this.

KT

pic.

MSD calls it a "100V/1A diode".

KT

Thanks....

So can just place the diode in-line before the charge light in the dash behind the guage?

KT

i believe you want the diode inline with the switched hot to the box (form your IGN switch) thats what my bok says anyway

Gee or read the manual they actually tell you that you may need to use an early Chrysler ballast resistor as part of the install. Had to do this on the 944.

Mike D.

the MSD paperwork ( above ) reads differently.

KT

Just did the install....it works...

Where did you put the diode, Mike, I want to do this tomorrow?

KT

QUOTE (trekkor @ Feb 27 2005, 03:45 PM)

Where did you put the diode, Mike, I want to do this tomorrow? KT

put a set of male and female terminals on the diod and do it right at the indicator is my guess (no cutting or splicing necessary if you solder termianls onto the diode

Put it on the D+ lead to the bulb.....had a 50/50 chance of fucking it up...did it right the first time...it's directional....

50/50 HUH? Not so good odds.

I NEED the real story!

I want the electricity to go one way, to the bulb, right?

KT

Got it!

Crimped on a terminal to each end with heat shrink between 'em. Works great. No more run on.

KT

Still need to open up the plug gaps

So how come this never went to the classic threads?