MSD Digital 6+ confusion, think my box may be fried?

[Guest 73Turbo240z]

Alright, i'm writing this from the passenger seat of my Z as i sit in the driveway.

 

as you all know, i had been having a problem w/ the car cutting up above 5krpm's, last night we did some more poking around with the ampermeter, and still came up with no solid conclusions, we started the car multiple times that night, this was less than 24 hours ago. It never gave me any trouble.

 

Fast forward to now... heres things that have changed...

1. installed an MSD blaster 2 coil that thumper had to see if the HVC coil i had was bad. since the car won't start, i swapped back to the HVC assuming that perhaps the blaster 2 was incompatible with the DI6+ box, however niether the blaster 2 or the HVC is sparking.

2. tried out my new battery charger (i think this may be my cause) i used it on the 2a slow charge for about 5 minutes, the 10amp fast charge for about 20 seconds, and the 50amp starting assist for about 5 seconds. I did all this so i could see what kind of voltages the battery would see when i did this, i went at my highest to about 16.4 volts when in that 50amp mode.

 

Now, i've gone through and re-read the MSD installation instructions... according to what i've read, the MSD works of switching the ground to the coil to cause the coil to collapse/fire.

 

According to MSD the red small wire leading to the coil should have 12v when the car is in the on position. And the ground should be a ground.

 

According to MSD the DI6+ box is compatible with all oem coils, blaster style coils, and the HVC coil, so that rules out my incompatibility theory.

 

The car started with my HVC last night, and thumpers blaster 2 was driving his car around prior to us pulling it out to put in mine 48 hours ago, so the odd's of both coils failing are nearly impossible, so i assume there good.

 

Heres where it gets wierd though.

 

With my ampremeter hooked up, negative to negative coil wire, positive to positive coil wire... i get nothing, crank the engine, i get nothing, however the MSD boxes LED fires, so does the MSnS's, so at a very basic level, they indicate they are functioning.

 

Now, take the ampremeters ground, go to the battery ground, and test the coil leads positive with the positive ampremeter probe, now i'm seeing .5v with the car COMPLETELY off.

 

Now take the ampremeters positive probe and stick it on the coils ground wire that comes from the MSD box... it too, shows .5v..

 

This is where i began to think my box might have fried internally when i had the charger plugged in. However, MSD's install states the box can handle short periods of up to 27 volts, and extended periods of 16 volts, so per MSD's instructions, i still haven't gone over there designed parameters.

 

Then i flip over to Ohm's, check the positive and negative coil wires coming out of the MSD box, i make a small slice in the wire shielding closest to the box so i can get a probe on it, and take my other measurement at the o-ring terminals that go to the coil...

 

both the positive and negative wires from the MSD box read 7.6 ohms which if i recall right means they are not bad.

 

So thats where i sit, freezing my *** off in my driveway @ 10pm at night trying to figure this out.

 

So far the big indicators that somthing is fubared internally box wise is the .5v on both lines to the coil, the unlikely chance that 2 coils failed completely at the same time, and the fact i can't get it to spark from the coil manually.

 

That being said i'm now out of "swappable" parts, i can't ask thumper or on3go to unwire there MSD boxes to test that with, thats too much of a PITA. so i'm turning to you guys for ideas, i'm no electrical expert, so i figured i'd ask you guys since some of ya'll are WAY more electrical savvy than myself.

[Guest 73Turbo240z]

Alright, inside now, got a couple beers in me, so my logic may be a little fuzzy given my intake rate at the moment... but is this diagnosing idea plausible.

 

If the MSD supplies the coil 12v as the MSD manual says, and it triggers that coil to discharge by interupting the ground, then in order to see if it's just one side of the "channel" circut that controls the coil is damaged, could i not hook up a wire straight from the 12v of the battery to the 12v of the coil? and then run another seperate wire from the ground terminal to the ground on the battery, and thus trigger the coil myself to ensure that it is good? or at least functioning?

 

and then beyond that, hook the MSD coil ground back up to the coil, and leave the 12v off the battery hooked up, cause if the MSD is still switching that ground (which i haven't been able to figure out how i could verify that) then giving it 12v off the battery should allow the car to run no?

[getZ]

That's funny you mentioned fuzzy logic. That's a real electronics word, but okay enough with my geeky sense of humor.

 

I've never used a digital msd, but have used a 6AL and crane HI-6TR. Essentialy they do the same thing and are made need to be intergrated with the stock electronics. They are still an interface between the stock control and the coil.

 

First, that 16 volts should not have hurt the system. Most manufacturers will build in at least a 20% tolerance range. Remember most cars will go to at least 14volts so that extra 2 volts should still be okay. I don't think that should hurt it.

 

Voltage across the coil is difficult to measure with a voltmeter. Why? You are trying to measure a series of pulses and meters don't react fast enough. Even if it did react quick enough it would look like it's just jumping back and forth. I'll see if I can attach a picture of the signal. I still have it on my computer somewhere.

 

If the coil seems be completely dead I would go back and check how you have it wired.

 

Did you use the ignitor? If you are using the stock computer, you have to use the ignitor or equivalent. The computer output is a very low current output and cannot drive most devices. That is why an ignitor (or transistor) is used. The MSD goes between the ignitor and the coil. Most of the timing control comes from the computer, although I think the digital msd can do some other timing adjustments as well as rev limit. My crane unit had the ability to retard the timing based on a boost sensor.

[getZ]

I couldn't find a picture, but I found my old post. The picture is kind of small, but you can get an idea of what the series of pulses looks like.

 

http://forums.hybridz.org/showthread.php?t=103361&highlight=ignitor

[Guest 73Turbo240z]

alright, i'll see if i can answer this a little more orderly:

 

1. i figured 16v wouldn't hurt the system, per the MSD manual it speaks of having a built in polarity protection circut for backwards hookups, and that it has an overcurrent cut off circut. It states that it will begin working again once the surge or polarity is corrected.

 

then theres this, quoted directly from the MSD manual "the MSD can be used with 16 volt batteries and can withstand a momentary 24 volts in case of jump starts, the ignition will deliver full voltage with a supply of 9-18 volts and will operate with a supply voltage as low as six volts"

 

that being said, my battery once taken off that charger and for the duration of my messing with it last night, was operating at 13.1-12.2v last night, and the charger never peaked 16v, so now i'm questioning the box being "fried".

 

if the battery charger put out that 50a setup for starting the car, and that was going directly into the battery terminals, of which the MSD takes its power as well, and niether the + or the - is fused since the MSD install never called for it, could the charger in 50a mode have maybe pushed the MSD over it's limit? I've not been able to find what the max amperage capacity is for the box.

 

This MSD box has a built in retard function, a starting retard, 2 rev limiters, and a pleathora of other options, however, i've only wired it up for the basic function of driving the car, so all retard/limiter functions are unwired/inoperable. Additionally this car is running on MSnS + the MSD D6+ box, so there are no stock components for it to interact with other than the 83' ZXT dizzy.

 

The MSD gets it's signal fromt he MSnS box, the MSnS box takes it's reading from the 83ZXT dizzy and it's internal CAS. I'm not familiar w/ this ignitor that your reffering too, this is where my electrical savvy falls short.

 

As far as i can tell my wiring is right, the car drove for weeks with it wired this way and the miss above 5krpm, it only stopped working after i did the things listed in my 1st post. This is where having a spare entire MSD box to swap in would be a life saver, i get frustrated w/ electrical too easily.

[Guest 73Turbo240z]

 

theres the basic wiring diagram from the MSD manual...

 

red gets it's signal from a relay output per the MSnS instructions, and the signal (white) gets it's signal input from the signal output of the MSnS box.

 

the fact i'm seeing .5v on both sides of the coil wiring is whats really pushing me to think somthing fried in the box, there shouldn't be any voltage in the ground line from what i understand.

[fastzcars]

You could remove the spark plug wire from from distibutor cap lead comes from the coil and set it about 1/2inch from a grounding point, like a bolt on the shock tower. unplug the gren and violet signal wireplug if your using it , then ground and unground the white signal wire coming out of the MSD unit. Every time you unground the white wire you should see a spark jump from the coil wire lead. If you don't see a spark, double check and MAKE SURE you have a good ground at the MSD large Black wire. I think the instructions are at page 10. I just went through this procedure last week , so it's still fresh in my mind. See if that helps.

[Guest ON3GO]

did you fix the rich spike yet? thats the problem.. like 240hoke said.

 

mike

[Guest 73Turbo240z]

swapped in a MSD 6AL this morning along w/ a blaster 2 coil, car runs, and my 5krpm issue is gone...

 

i suspect the DI6+ box was to blame all along.

[Guest ON3GO]

did you just swap out coils 1st to see if it was the problem??

 

mike

[Thumper]

Yeah he swapped out my known to be good coil and it still didn't work. So we swapped the msd box out and all is good no more top-end miss.

[Guest ON3GO]

i cant see how the box would be a problem..

did you try the fualty box on teds car to see if its the same problem?

 

mike

[Guest 73Turbo240z]

nope, wayyyy to much wiring to change over, if you want we can bench test it on yours since your box is in the engine bay, and not under the dash.

[getZ]

That's too bad the msd went out. They are kind of pricey.

 

Just an FYI, an ignitor (transistor) is used to drive the timing signal because most computers do not output a strong enough signal. In general, most computers are designed to be small and fast, not handling large current. Like trying to use your flashlight battery to start a car.

 

Relays can be used as well, but mechanical devices always have some sort of bounce when they contact.

 

I didn't realize you were running a Megasquirt. Does it hook directly up to the msd white wire?

[Thumper]

I didn't realize you were running a Megasquirt. Does it hook directly up to the msd white wire?

 

Yes megasquirt hooks directly up to the white wire.

[Guest 73Turbo240z]

That's too bad the msd went out. They are kind of pricey.

 

Just an FYI' date=' an ignitor (transistor) is used to drive the timing signal because most computers do not output a strong enough signal. In general, most computers are designed to be small and fast, not handling large current. Like trying to use your flashlight battery to start a car.

 

Relays can be used as well, but mechanical devices always have some sort of bounce when they contact.

 

I didn't realize you were running a Megasquirt. Does it hook directly up to the msd white wire?[/quote']

 

yea, i'm going to take the box apart and look for a fried resistor/diode as a suspect thats the culprit... if i can't find anything, i'll send it to MSD for anaylsis and decide what i want to do about it then...

 

i really like the DI6+ box... i'd prefer not to lose it.

[Guest ambersdad]

Sorry to hear about your troubles. I'm just starting my project so I'll have an MSD 6A available as there's no need for it to simply sit for the year or so that it's going to take to finish. Make me an offer - glad to help if I can.

 

Vic

1981 280 ZXT Stroker Project

[Guest 73Turbo240z]

thanks for the offer, luckily i managed to source a MSD 6AL from a local mustang performance place to get myself up and running in time, thanks!

[jeffp]

I am running a MSD 6A box, and it to has developed a misfire @ 5K rpm's. The HVC coil was bad. So I decided to go with the sure fire Mallory volt master coil.

So I still haven't finished up the misfire problem yet. I had to buoild some filter circuits to filter the electric motors in my car, fan, waterpump, and intercooler fans.

Anyway, I had to pull the radiator, while I was at it to have a fitting welded on the tank for the temp sensor. I completed that today.

Anyway, I went to the Pomona swap meet last weekend and bought a 6a for $30.00 I decided to disect the box, and when I got it opened up, WHAT A JOKE. No wonder the box cant take vibration at all, and no wonder it fails looking at the components used in the unit. The circuit board is a single sided board, and the soldering looks like it was assembled by my wife while she was watching All my children.

I am sending the box out to have a schematic done on it, yes it is time for some modifications to the box.

Now, if you want to, send me the box, and I am quite sure I can effect repairs to the unit, the circuitry is such a joke

[getZ]

I don't think the digital 6 is the same. I thought it all encased.