$20 Ignitor Replacement/upgrade

[mmganga]

Thanks Joe!!! It makes sense and thanks for all the detailed explanations. One problem I have is that my original harness seems to be gone (I've had this MSD for 2 years almost and now it's crapped on me). So it would be easier to install with the MSD adapter.

If you would be so kind as to read this post which I asked specifically about how the MSD works:

http://forums.probetalk.com/showthread.php?t=1701083793

And have a look at the image there (same as what I currently have in the 94 disty):

http://www.gilstarr.d2g.com/All_Pics...cs/MSD_057.jpg

The problem is that the pin which originally connects to the tach (the third) is disconnected in this harness installation. However it's really strange since the MSD itself supposedly picks up the tach output from the WHITE wire in the picture. The yellow/blue is also connected to this white wire (same node), and my tach has worked fine!!!

Would it be possible to install it like this or should I try to find and use an old harness adapter to go back to the original install?

THANKS!!!

[Joe Bialy]

Originally Posted by mmganga

Thanks Joe!!! It makes sense and thanks for all the detailed explanations. One problem I have is that my original harness seems to be gone (I've had this MSD for 2 years almost and now it's crapped on me). So it would be easier to install with the MSD adapter.

If you would be so kind as to read this post which I asked specifically about how the MSD works:

http://forums.probetalk.com/showthread.php?t=1701083793

And have a look at the image there (same as what I currently have in the 94 disty):

http://www.gilstarr.d2g.com/All_Pics...cs/MSD_057.jpg

The problem is that the pin which originally connects to the tach (the third) is disconnected in this harness installation. However it's really strange since the MSD itself supposedly picks up the tach output from the WHITE wire in the picture. The yellow/blue is also connected to this white wire (same node), and my tach has worked fine!!!

Would it be possible to install it like this or should I try to find and use an old harness adapter to go back to the original install?

THANKS!!!

Piece of cake!! Those are good images.

MSD red is +12V just like you said. Feeds the coil and pin 'B'.

MSD white trigger wire is not needed. This is the output of the old ignitor. If the old ignitor is dead, there won't be any output. Maybe that's why so many MSD installs are troublesome. A dead ignitor won't make a good trigger.

MSD black will go to pin 'C' of the HEI. This is the coil (-).

To get your tach back, you'll need to buy a 1,000 ohm resistor at Radio Shack. One end will go to the old original Probe tach wire (yellow/blue). The other end will be tapped onto the black MSD wire which goes to pin 'C'.

[Joe Bialy]

Originally Posted by mmganga

Joe, one more question since you make everything so clear!!!

What's the idea of the ignition 'pick-up' or 'trigger' point? I don't see how there can be so many points where different things can pick up from. Just for example, this MSD was connecting to the old ignitor and using that as a pickup point. The HEI you propose (and which I am sure will bring back the tach once I put that 1K resistor in there) uses the first wire of the ECU, am I right?

Also the tach pickup can come from the post on the distributor (the third connector which is only in the original harness, not in the MSD), or the center ignitor, or the negative of the HEI (with the resistor).

All these options are slightly confusing....


THANKS!!!

The 'pick up' or trigger point only comes from the ECU. This is the blue/orange wire. Unfortunately, this signal from the ECU is not very robust so it can not do anything that requires power, like firing the ignition coil directly. The Ignitor is a booster that puts some balls behind this signal so it can switch coils on and off. The ignitor also acts as isolator too- so that major arcs and sparks and inductive kick backs don't feed back through to the ECU and kill it. I think that's why it has two transistors in it instead of one.

The MSD's white wire is the 'points' wire. In a points type ignition, its good to have a little bit of current flowing through them when they switch. The MSD box provides that current but unfortunately, the ECU's Bl/O wire isn't robust enough to handle that current directly.

There's also a second problem here- probably even more important too- the ECU's trigger doesn't switch exactly like the MSD's white wire would like it to. The MSD sparks when the white wire goes open, or rises up to +12V. The ECU Bl/O trigger is the opposite- it wants a spark when it goes to 0V. The ignitor convieniently provides exactly the same signal as the points did on a points type ignition system and feeds the MSD exactly what it wants. The only fundamental problem is that if your ignitor is dead this won't work- and most people put in the MSD in the first place because their ignitor died.

As far as tach signals go, the Probe's coil has a built in 1,000 ohm isolating resistor to feed the Y/Bl tach from the coil (-) terminal. That tach feed is the center wire on the three pin plug, or the end terminal on the coil itself (the three terminal coil adapter plug thingie crosses those two wires internally for some stupid reason). So, any way you can get a 1,000 ohm resistor between the tach and coil (-) will work. Whether its the internal Probe coil one or a separate one, it won't matter. Just get 1,000 ohms between Y/Bl and coil (-).

[Joe Bialy]

Originally Posted by Shrep

Okay...now...I am confused...

There has been a lot of mention on this thread about the MSD being used to replace dead Ignitors...I was under the impression that it still utilizes the ignitor...seeing as it connects to the coil trigger inside.

Well, according to the last pictures of an MSD harness posted here by mmganga, it DOES use the old ignitor. But, some of you add your own 3055 transistor to replace that ignitor. Hopefully, the little metal link is removed to completely eliminate the dead ignitor.

[Joe Bialy]

Originally Posted by mmganga

What I don't understand in turn is how the tach signal can be obtained from more than one location ;-)

The only place the tach signal comes from is the (-) side of the coil, through the resistor.

[mmganga]

Right now I see three configurations:

1) stock configuration - tach is taken from pin 3 of inside the distributor (first pin is +coil, second is -coil);
2) MSD configuration - tach is taken from the old ignitor which also is used as a pickup point for the MSD (the white wire in the pictures is a common node for the MSD, the old ignitor, AND the tach);
3) HEI configuration - tach is taken from the negative of the coil through the 1 kOhm resistor.

[Scott]

I posted this in the other thread, but for those of you worried about high rpm problems: (just a suggestion )

Maybe this will work...note the "higher RPM" remark.
If it's the coil:
http://www.msdignition.com/1msdcoil.htm

MSD HEI coil:
MSD HEI Coil, PN 8225
Replace the stock internal coil of your HEI with an MSD. The coil features lower inductance and high temperature windings which allow the coil to charge faster delivering increased spark energy at higher rpm. The MSD Coil mounts in the stock HEI cap and installs in minutes. To receive the most from the coil, it is recommended to replace the module with MSD's powerful HEI Module, PN 8364.
MSD HEI Coil - PN 8225
CARB Approved, D-40-15

[Joe Bialy]

Originally Posted by jpk2379

Well I'm done trying the HEI. I'm getting a new disty tomorrow. At least this is the first problem I've had with this car since I got it which has been about 5-6 mos. Oh well, what can you do. It was some good info though and simple enough to do, just too bad it doesn't work on the 95+ models.

You should have read all the previous posts, there's no reason it won't work on a '95. The easiest way is with an external coil, then you don't even touch the old ignitor.



Originally Posted by Omaha95PGT
'95+ distributors are different in their layout. I had posted up some '95+ disty anatomy pics on the old PT, but I'll repost them here for the continued development of this mod.

Personally, I'd like to see the advancement of this mod to include not just a simple repair for blown ignitors, but to include the addition of a "hot module" (performance HEI module) and the wiring of a high discharge coil. Sort of a simpler and less expensive alternative to the MSD setups.

Joe_Bialy, can you post up a wiring diagram that would include an external coil?

Here are the '95 disty pics:


http://home.comcast.net/~mmunoz70/z/95disty08.jpg


An external coil on a '94 like mine is pretty straightforward:

Besides the new coil, you'll need a new 1,000 ohm resistor to feed the tach because the Probe's old coil has this resistor built into it.

1) Do not plug in the 3 pin connector to the disty at all.
2) Pin #1 Black/Pink (power) will be new coil (+) and HEI "B".
3) Pin #2 Yellow/Green (IG-) will be HEI "C" and coil (-) and one side of the new 1,000 ohm resistor.
4) Pin #3 Yellow/Blue (tach output) will get the other side of the 1,000 ohm resistor.
5) Big connector pin 6 Blue/Orange goes to HEI "G" as before.

1,000 ohms is Brown-Black-Red, 1/2 watt will be fine. $.50 at Radio Shack.

The 3 pin connector (C170) is numbered 1-3-2. Not 1-2-3 as the incorrect All Data connector diagram shows. The correct order is:
1= circuit 2 Bk/P power
3= circuit 731 Y/Bl tach output
2= circuit 732 Y/G tach signal (ignition ground) or "IG-" on the DLC.

The faded wiring on my car makes it impossible to tell Y/Bl from Y/G. They both look like Y/G to me. You can be sure you have the right Y/G (IG-) wire by checking for continuity between pin #2 of the disty plug and the (IG-) pin of the DLC-its the same wire.

On to the '95:

You will need to do continuity checks to see where the three pins of the old ignitor go to. I suspect its electrically identical to the '94, just repackaged. If that's the case, then it will connect the same way. You don't have the strap to remove like the '94, but instead, you'll need to cut the corresponding pin on the ignitor. One ignitor pin will mimic the "G" function, one will mimic "B", and one will mimic "C" on the HEI diagram.

Or, screw the old coil and use an external one. Then you can forget about the ignitor all together. Just make sure the three pin C170 is the same configuration as the '94 is, and use the same Blue/Orange trigger wire on the big connector just like on the '94.

[Omaha95PGT]

The Joe Bialy '93-'94 Distributor HEI Module Mod (aka blown ignitor fix)

Parts/tools needed:
-HEI module 4-pin
-4 lengths of wire about 3 feet each (trim to fit...some will only end up being a few inches)
-wire stripper/crimper
-wire "spade" type connectors that will fit the HEI module conectors. These should be "hooded"/insulated type
-razor blade or scalpel to strip insulation on wires you don't cut
-electrical tape, heat shrink tubing or paint on insulation
-30 watt soldering iron
-silver solder

Procedure:
Use this picture as the wiring diagram reference: http://ryand2.cjb.net/my%20pictures/...itor/hei01.gif

-remove spark plug wires off disty cap (label them)
-Remove disty cap
-remove rotor (remember it's orientation)
-you will now see this: http://ryand2.cjb.net/my%20pictures/...nitor/hei2.jpg
-remove the strap so it looks like this: http://ryand2.cjb.net/my%20pictures/...nitor/hei3.jpg
-reinstall the rotor
-reinstall the disty cap
-cut the wire closest to the firewall on the 6-pin harness. Leave a lot of wire on the disty side in case you need to reverse the mod.
-strip then solder a wire to the ECU side (not the side still connected to the disty) of the wire that you just cut. Connect that wire to the "G" connector on the HEI module. Insulate soldered splice point.
-tap (do not cut) and solder into the wire closest to the firewall on the 3 wire connector. That wire should go to the "B" connector on the HEI module. Insulate soldered splice point.
-tap (do not cut) and solder into the wire closest to the radiator on the 3 wire connector. That wire should go to the "C" connector on the HEI module. Insulate soldered splice point.
-connect a wire to the "W" connector on the HEI module, then connect that wire to the "GND" on the HEI module.
-then connect the wire on the "W" and "GND" to the negagive battery lead or any grounding point on the chassis
-mount the HEI module somewhere secure

That's it. You are done.

If you are using a more complicated setup such as one utilizing an external coil, then you'll have to hook up the resistor, etc. For a simple '93-'94 disty ignitor fix, this is all you have to do. The '95-'97 wiring is similar but still in the testing phase

[Joe Bialy]

Originally Posted by j1mmy

I appologize if i have been irritable on this topic. I just have been under alot of stress/pressure lately. I have been having problems concentrating and im really not that mechanically inclined and really have never seen a dist apart before.. But thanks alot for the patience and help. I dont know what I would do without such a great forum.. Thanks alot Joe and Omaha!! Keep up the good work!!

Thanks to my NEW JOB AT *FLAT ROCK* making Mazda6's and '05 Mustangs, I get about three minutes a day to read and respond to these things. Everything you need to know is in a previous post here. Omaha95PGT's write up is superb and will take this a long way. Thanks!

The '95 disty has a different ignitor, you will need to do a little checking with an ohmeter to find what ignitor terminals are equivalent to the old '94 style ignitor, but this shouldn't be hard. They both work the same way, they just look different. Bottom line is that one of the ignitor terminals will need to be cut to eliminate it from the circuit, just like removing the strap on the '94's. I can't tell you which of the three terminals it would be though. Or, maybe better yet, just cut all three of them all out.

If someone has a '95 disty they want to send me, I could figure that out and post the info for all to know.

[Omaha95PGT]

Originally Posted by j1mmy

Just curious.. is there any other way to replace/fix the ignitor without this mod? Does MSD or jacobs etc make any product that would be a replacement?

Did you do the fix?

MSD will hook up to the PGT without a problem. Refer to a write up that is stickied at the top of the N2O forum.

But then an MSD box will cost ~$150

[Shrep]

Originally Posted by j1mmy

Just curious.. is there any other way to replace/fix the ignitor without this mod? Does MSD or jacobs etc make any product that would be a replacement?

As far as I can tell this is the first low cost solution to the Ignitor problem in our cars. The other option being of course to replace the disty.

At $275-$300 I'd go with the HEI module mod myself.

[Joe Bialy]

Originally Posted by Drummerboyevil

Well it's all hooked up like it's supposed to be...

The three pin is still all connected to the disty plus splice into the 12v+ and the ig-, and then the (what I am sure is the - input from ECU) is cut and goes from the ECU to the HEI, but nothing. I tried testing the - from ECU by putting the ground on the multimeter on the wire from the ECU and positive on the positive battery terminal. and it as always ground until you turn over the car and it drops to 8v. This confuses me because it seems like the dropping to 8v could be due to the starter taking so much power, and the wire shjould be pulsing at 5v. Strange...

I'm using the wire all the way at the end closest to the firewall on teh 6 pin connector.

I guess it's time to take apart the disty and go from there.

With the ECU disconnected and the HEI's G pin grounded, you should see Vbatt on B and also on C pins.
With G at Vbatt, you should see a few volts on C and Vbatt still on B.
As soon as G goes from Vbatt to gnd, the coil should spark.

8 volts would be about normal for a cranking engine. You should do the above tests without cranking the engine.

Did you ground the HEI module through its mounting hole properly?

Also, I'm not sure if the ECU can handle its output wire taken to ground when you were doing your tests. It might not hurt it, but I'm not sure. You should be a ble to see the ECU's pulses with a voltmeter or an LED as it tries to spark the ignition- maybe not see it go all the way to +5 because they're pretty short, but something should be there nonetheless. If you use an LED, be sure to have a resistor in series with it, like 270 ohms or so, and be sure the polarity is correct too.

You don't have any diagrams we could look at do you?

[Drummerboyevil]

Originally Posted by Joe Bialy

Did you disconnect the old ignitor from the coil?

No, but that shouldn't affect anything...

[Joe Bialy]

Originally Posted by Drummerboyevil

No, but that shouldn't affect anything...

Well, the old ignitor's output goes to the coil (-) terminal and so does the new HEI. So depending upon how the old ignitor failed, you could be bypassing the HEI's output to ground here. OTOH, if the old ignitor is good and its input pin is left hanging open (like it is when the Bl/O wire is cut), it could be baising itself 'on' also effectively bypassing the HEI's output.

Easiest thing to do is take the cut off disty side of the Bl/O wire and tie it to ground. Next thing to do is eliminate the old ignitor's output connection.

[Joe Bialy]

Originally Posted by j1mmy

Sorry!! My bad i was just doing this off the top of my head ( i dont have the greatest memory). The B pin had pretty much the same voltage as the battery. It was the "C" pin that had a really low voltage.. so THIS is pointing to bad coil right??

Continuous low voltage on C pin would mean to me that the HEI module is always turned 'ON'. Disconnect the G pin and ground it, then read your C pin voltage.
If its still low, you probably have a bad HEI module.
If it is higher-close to battery voltage- your HEI module is OK. Hook up the G pin again and see if C goes low. If it does, you have ECU problems.

[j1mmy]

Originally Posted by Joe Bialy

1) During all of the following, unplug the 'G' terminal of the HEI module so that it is not connected to the ECU and turn the ign key ON:

2) Measure the voltage on the 'B' terminal. It should be the same as the battery voltage. If not, there's a problem with the Bk/P wire circuit.

3) Measure the voltage on the 'C' terminal. It should also be the same as the battery voltage. If not, the coil primary circuit is open- maybe bad coil, maybe problems with Y/G wire.

Okay, i was following your instructions from this thread..http://forums.probetalk.com/showthread.php?t=1701085800

And so i unplugged "G" and turned the key to ON.. Measured Terminal "B" it read the same voltage (or damn close) to the battery. I then checked "C" with G still unpluged and it was like really low.. 1V or lower.. something like that.

So what does this mean? I am hoping it means my coil is bad or something because I ordered a new dist just in case.

Also my HEI module is brand new.

[Joe Bialy]

Originally Posted by j1mmy

And so i unplugged "G" and turned the key to ON.. I then checked "C" with G still unpluged and it was like really low.. 1V or lower.. something like that.

So what does this mean? I am hoping it means my coil is bad or something because I ordered a new dist just in case.

Also my HEI module is brand new.

Whether its a brand new HEI or not, C should be at battery voltage with G grounded. If it isn't that HEI is probably bad.

Sounds like you need an electrical helper wherever you're at to help sort this out. I can't tell you what "1V or lower.. something like that" means. Is it 1V, is it 0V like an open circuit, is it 0V like a short circuit, or what?

1V tells me the HEI is bad.
0V like an open circuit tells me the coil is bad.
0V like a short circuit tells me the HEI is bad.

This HEI mod is too simple of a concept to create this much trouble for you.

[Joe Bialy]

The HEI module can be viewed as a fancy relay. Small signal pulses into it provide large power handling contacts of it. The input is G and ground, which would be like the relay's coil. The output is C, so you can look at it as a relay contact from C to ground. Open circuit contacts do flow any current, closed circuit contacts can flow a lot of current.

You can substitute a lamp instead of the coil and SEE if the HEI is working for you. The lamp will mimic the coil's operation and show you if current is flowing. Use any 12V incandescent lamp, like an old fog light, or a marker light, it won't really matter. You could probably even use a headlamp. Don't use an LED because its polarity sensitive and won't light if put in backwards.

Leave the B pin hooked up as normal to the harness. This is power to the HEI. Disconnect the C pin from the harness and put the 12V light bulb between pin C and pin B. As you crank the engine, you should see the light blink with each pulse from the ECU. If this is successful, you know the HEI is OK.

Now, put the lamp in series with the harness wire that went to C. It should still blink when the engine is cranked. If it does, you may have a bad coil, or some other problem the HEI mod can't fix.

To check the coil, take off the cap, or otherwise get to the tower terminal of the coil and create a spark gap from the tower to ground to mimic a spark plug. Now take the wire that went to C and rapidly flick it to ground. Each time you flick it, you should see a spark from the tower of the coil and you will also see a spark on the wire where you're flicking it to ground at.

[sox4130]

ok since im not getting spark & im willing to give this a try to see if its the ignitor. will i be able to undo it if it doesnt work?

-Isaac

[ya_whatever]

Originally Posted by sox4130

ok since im not getting spark & im willing to give this a try to see if its the ignitor. will i be able to undo it if it doesnt work?

-Isaac

What I did was I took a small piece of shrink wrap and put it over the end of the strap, and a small ball of fun tack to hold it down, it'll hit the interuptor wheel if it's not held down but you dont want to make it much higher either. Then once I got it working I cut it out. I just wanted to make sure I didnt mess anything up.

[ya_whatever]

I used the coil with the HEI, still alot cheaper than a new disty or msd 6. With the coil you dont have to worry about removing the internal strap just leave the 3-wire connector off.

[Joe Bialy]

Originally Posted by Rusty6

Anyone know what the specs on the resistor need to be. Going to an electronics components dealer, looking at the online list of 1k resistors, there are alot of different kinds.

The very worst case would be if that resistor saw 12 volts across all the time. From that we can figure out its wattage using P=E*E/R. 12*12/1,000=.144 watts. Double that to keep it cool and you get ~1/4 watt. So, any 1/4W or higher 1,000 ohm job will work.

Omaha95PGT's suggestion to use 1W is good because you will have a resistor physically big enough to be rugged and easy to hook up to.

[Shrep]

Sorry for the double-post.

Okay...I understand the schematic posted on pg2 of the other thread but I was wondering how you would wire in a msd box with this...it seems that the hei is effectively hooked up exactly how the msd box is...but I don't want to loose the features of the msd. can anyone help me with this? I still want to bypass the Ignitor.

Thanks!

[Omaha95PGT]

Originally Posted by Shrep

Okay...I understand the schematic posted on pg2 of the other thread but I was wondering how you would wire in a msd box with this...it seems that the hei is effectively hooked up exactly how the msd box is...but I don't want to lose the features of the msd. can anyone help me with this? I still want to bypass the Ignitor.

Are you talking about hooking up an MSD with the HEI? It's been done:

http://forums.probetalk.com/showthread.php?t=1701093012