Some help getting engine started

[e9Leveque]

So as some of you may know, I had pulled my engine in order to paint the engine bay and in the process had upgraded/restored most of the non-engine components. I put everything back together and yesterday was trying to start the engine for the first time in a few months. No luck. I had Don on Facetime and we walked through some options but weren't able to resolve it. So that I take some of the burden off of him and his expertise, thought I'd post here for some thoughts.
So that we lay out the case correctly. 1972 CSi. Was running fine in December before I started this. Engine pulled by disconnecting every wire running to it but not removing distributor, which I left as-is. Changes to the car by me are as follows:
1. New Bosch starter (the smaller model most are recommending these days)
2. New battery moved to trunk but confirmed good power being delivered to engine bay area
3. Ignition coil changed from old Bosch blue to MDS black
4. Pertronix distributor not touched
5. Ballast resister (ceramic) not touched
6. Distributor to spark plugs wiring changed prior to engine pulling
7. New spark plugs installed after engine pull

The problem. Engine cranks but does not fully start. The steps taken to diagnose
1. Don had me disconnect starter electrically from system and run a "home run" wire to starter so that I can touch other end to battery and fire starter directly. That works, so starter deemed functional
2. Using multimeter to test, ignition coil has 12V at its positive side and had 5V at negative side (with MDS black coil). Ballast resister had 10V on top dropping to 1V by its bottom. Under Don's direction, removed ballast resister from system and wired both ECU lead (white wire) the other wire going to ballast directly to the ignition coil. Getting 12V on one side, 5V on the other. Firing the starter did not give me a spark out the top of the ignition coil. Question became whether my new ignition coil is the problem so I re-installed the old Bosch blue that was in the car at the time of it running. With that one, see 12V at positive and 1V at negative. No spark out the top when firing starter. Interestingly, when removing the black wire going from ignition coil to the distributor, the voltage at the negative side of the coil is 12V and voltage at tower is 12V. So when distributor is connected and car has key turned on but not cranking, the distributor being connected is causing 11V drop across the two leads of the ignition coil.
3. Pulled the top off the distributor cap to make sure the rotor is spinning. It is when starter cranks. The latest thinking is that perhaps the Pertronix unit has been fried in some way that it's shorting out or not firing correctly. When it's connected, firing off the starter causes that 1V at negative side of coil to rise to 4.5V
So, questions:

1. Utility in changing out the Pertronix unit? It does not have a model number on its side, only a lot or serial number, but from assessment online should be replaced with a 1868 Pertronix unit
2. Utility in a new Bosch blue ignition coil? The blue appears to have internal resister so would allow me to keep the ballast resistor out of the system, which may simplify things.
3. I'll recheck all of my ground points. I have two large grounds, one running from lower engine block to battery tray to side strut on the battery side, the other from screw on transmission to the inside wall of the transmission tunnel. Since I did paint the engine bay and tunnel, I'll make sure that paint is scraped off in these locations so that I know I'm getting good contact for the ground. The battery in the trunk is separately grounded to one of the large bolts that secure the seat belts bolted directly into the frame.

Sorry for the long post but thought better to put out all of the information I know so that you aren't having to ask as many clarifying questions.
I had been hoping to have this running in time for German day at the local large cars and coffee this weekend, but I may be a visitor instead of participant this year.

 

[Dick Steinkamp]

What do you mean by "engine does not fully start"?

 

[e9Leveque]

I mean that the starter fires and the engine whines but I'm not getting ignition. Fan turns and belts turn while starter turning. Overall appears to be an electrical issue somewhere between coil/distributor so that I'm not getting a spark.

 

[HB Chris]

Definitely don’t want resistor and blue coil so that is good. Pertronix needs full 12 volts even though blue coil puts out 9 volts. What if you disconnect black tach wire? If it is grounding car won’t fire.

 

[e9Leveque]

We believe we tried disconnecting the black wire, that didn't solve the issue unfortunately - I'll try again. I'm a bit newer to this portion of the engine, so not clear on how if the blue coil puts out 9V but the Pertronix wants the full 12 how that would work. I understand not having the resistor at that point, but what do I need to make sure Pertronix gets all that it needs. Regarding the grounding, I was wondering whether it was a "partial" ground. I had this issue just this weekend in my MG where headlights wouldn't light - I could power them directly from an external battery and if I checked continuity on the ground wire it appeared fine, but no light when using standard harness. Adding a new ground directly from headlight to frame solved the problem.

 

[HB Chris]

Red wire to Pertronix is before it enters the blue coil, same with a ballast, it uses the terminal before the ballast resistor. Pertronix black wire goes to the other coil terminal obviously, you would have two black wires there.

 

[e9Leveque]

I'll check that wiring when at home to make sure that's how it's set up. I did take lots of photos when disassembling and tried to make sure all was put back together in the same way, but a second check-through to be certain is easy enough to do.

 

[StephenZ]

I'm no expert here, but maybe 20 years ago I had a brand new pertronix I installed on my 2002 that was randomly bad. No start and I went through everything...maybe got fried or was a bad one, but is it possible yours checked out?

 

[boonies]

Before you swap in a new pertronix you can test it with a 12v power source and a multi-meter.

• Use a jumper wire from the distributor plate (where the pertronix attaches) to battery ground
• Connect a the power (red) pertronix lead to battery positive.
• Touch or connect your multi-meter ,red lead to red wire and black lead to the black wire from pertronix.
• As you spin the distributor shaft you should see voltage move from 12v to about 1v or less. If you don't see that variation in voltage you have a pertronix issue.

Check your engine grounds to make sure they are good. I recall you painted the engine compartment, you may want to check to make sure that there is no paint under the ground strap at the firewall and on the engine.

 

[nashvillecat]

I’m trying to follow your travails via a tiny phone screen, so it is likely I am missing or misreading things. Have you totally bypassed your ignition switch to ensure that is not part of the no-start problem? Could you have inadvertently loosened or disconnected wiring at the fuse block? How about the center carbon button at the top of the cap? Could it have been jarred loose? Is ceramic ballast resistor still functional and intact? (They are robust, but not impervious to breakage.) Along same lines, could the pertronix be bad? Have you considered returning to Kettering’s tried and true points and condenser?

It seems fairly clear that the problem is ignition and not fuel related. Nevertheless, how about easy-to-check csi-specific items such as the djet relays, wiring/connection to the pressure sending unit or injection points at the bottom of the distributor?

 

[e9Leveque]

All good ideas. I'll do the test on the Pertronix with a separate 12V battery and multimeter. And yes, will check to make sure that paint isn't interfering with getting a good ground. Regarding the ignition switch concern, yes I have bypassed it. First, I am getting power through by turning the key to the "on" position so there's at least that. Second, I have a wire running directly to the starter which I can touch to battery terminal to initiate the starter firing, which obviously should then be connecting to ignition coil/distributor. So I can fire off the system directly, the signal is getting snarled somewhere in those last two. Some good next steps. Finally, regarding changing back to points, yes, I suppose I could do that, but the car WAS running before I started on this endeavor and if the points is truly the best way to go I can do it, but if the answer is simply swapping out a bad Pertronix or correcting some wiring I did wrong that seems far easier.

 

[sfdon]

Bottom line is no spark from coil wire to body ground when cranking.
Starter wire is home run to battery.

 

[2000CS]

Long shot, but - at least some - of the new "small" starters seem to have different solenoid function at the top connector on the solenoid. Originally this fed power while cranking directly to the coil, bypassing ballast, for a "stronger" start. Some new starters provide ground or weird low voltage while cranking instead. If you have it connected disconnect and try. Put a test light or voltmeter on solenoid male spade or stud without wire connected and see what it does while cranking.
May have fried something if it did ground.

 

[ScottAndrews]

This may be common knowledge to some, but in my experience not everyone is aware of how the Kettering coil ignition works.

When the ignition is on, one end of the coil is energized (typically at 12V). The other end is grounded through the points.

Current flows through the coil, building up a large magnetic field. If nothing happens to the current the coil passes the current, and the energy is dissipated as heat.

The coil is basically a transformer, so when the current in the primary winding (the 12V winding) first starts flowing , it causes a current to flow in the secondary. This current, of course has nowhere to go because it is connected to the air gaps of the spark plugs, and the overall voltage is not sufficient to bridge that gap with a spark.
When the points (or Pertronix solid state device) opens, the current flowing in the coil has nowhere to go. Since the magnetic field was already established when current was flowing, it now collapses. The rapid collapse causes a large spike in current in the secondary field, which DOES cross the air gap of th e spark plug, and this causes ignition in the cylinder.

So basic principles:

1. Do you have 12V to one side of the coil?
2. When the engine turns, does the ground side of the coil alternate between ground and open?

You should be able to test these with a multimeter and something to rotate the crank.

If the coil is not at 12V, then disconnect the 12V ignition wire and test the voltage. If if is at 12 then, then your coil is either drawing too much current, or there is some resistance in the ignition wire. if there is a ballast resistor, remember that Pertronix shows the red wire going to the ignition wire side of the ballast resistor, not the coil side (this may be why you are only seeing 9 volts at the coil and the Pertronix unit) See the diagram below.

With the Pertronix unit powered by the ignition line (and at 12 V), place the multimeter in resistance mode. Disconnect the Pertronix unit black wire from the coil. Rotate the engine and check that the resistance between the black wire and ground varies between some low value (less than 1 Ohm) and some high value (like infinity). If this does not happen, then double check that you have installed the magnetic sleeve in the distributor shaft. This is what the Pertronix unit uses to sense when to open the circuit.

If all of these work, then try a different coil.


I am a bit unclear how the starter bypass works. And your description is a bit puzzling.

"Second, I have a wire running directly to the starter which I can touch to battery terminal to initiate the starter firing, which obviously should then be connecting to ignition coil/distributor. So I can fire off the system directly, the signal is getting snarled somewhere in those last two."

The wire to the starter solenoid to the battery should only be energizing the starter solenoid, so you can crank the engine from the engine bay. It should not also be the source of current for the coil. That should be from the ignition switch to the ballast resistor and then to the coil (and, as noted above, the Petronix unit red wire should be on the ignition switch side of the ballast resistor.

Here are some snips from the Pertronix installation guide. This

one is for a MBZ unit, but the thereof operation is the same.

 

[ScottAndrews]

As an addition to the above post, the reason the coil generate a voltage spike is this: Sorry this is so long..

I won't go into the math behind this, but a very smart physicist names James Clerk Maxwell derived a set of equations (known as "Maxwell's Equations") that define the behavior of electric and magnetic fields. One of these says that, when current (electrons) flow through a wire, they create a magnetic field around that wire. Obviously there is no field around a wire that has no current flowing, but when current is applied, the field expands from zero to some intensity proportional to the flowing current (this is how an electromagnet works)

These equations are symmetric, in that not only will a current flowing in a wire cause a magnetic field, if you cause a magnetic field to move over the wire, the field will induce a current in the wire. This is how a generator works. In a nutshell, you spin wires in a magnetic field, and the spinning effectively causes the wires to pass in and out of the magnetic field, thereby causing current to flow in the wire.

You can use this property to cause current in one wire to "induce" current in an adjacent wire. So if you have two wires close to one another and pass current though one of the wires, the expanding magnetic field will cause current to flow in the adjacent wire.

There are two ways that this phenomenon can be applied. First is a simple COIL of wire. In a coil the adjacent wires are actually the same wire, but in the coil any segment of the wire runs parallel to two other segments of itself (one in the coil segment below it, and one in the coil segment above it). Now, when current is applied to the coil wire, the expanding field in the first coil segment causes a current to flow in the adjacent segment, and so forth. Interestingly because of the arrangement of the wires, this "induced" current flows in the opposite direction from the applied current (!!) What this means is effectively the CHANGE in current in the wire causes a current to flow the other way, thereby resisting that change. This is a bit like that strange compound we used to play with as kids (we called in Mister Pud), where you mixed cornstarch and water. If you held it in your hand is acted like a fluid, dripping over the sides, but the moment you pushed on it, or squeezed it, it would crack, like a solid.

So the coil (called an "Inductor") resists CHANGES in current, but once those changes stop, in a steady state it is just a piece of wire, with (technically) no resistance. The opposing current creates an opposing voltage, which is called the "back EMF". Remember these points, because they will become important below.

The other application of this phenomenon is when you intertwine two coils. In this case not only does each coil act as described above, but the one to which an external current is applied will induce a current in the other coil. This is called a "transformer". Interestingly the number of turns in the two coils do not need to be the same, so if the "primary" coil (the one that is driven with an externally applied current) has N turns, and the secondary (the other coil) has M turns, the resulting voltage in the secondary will be M/N times the applied voltage (note: because of the time changing aspect here, this only works if the applied voltage and current are changing all the time (as in "alternating current"). If you apply DC to a transformer nothing will happen except at the moment the current changes (remember this little factoid.. )

So, now we know all bout coils and transformers, what does any of this have to do with ignition systems?

The ignition coil in a car is a transformer. It has a primary winding and a secondary winding. The ratio of turns in these two windings is very high, so the secondary has many times more turns than the primary. For sake or discussion, suppose the primary has 100 turns, and the secondary has 10K turns. That's a ratio of 100:1, so if we apply a (changing) voltage to the primary, we will get a (changing) voltage in the secondary that is 100X higher voltage.

Now, the primary is still also a coil, as we described above. So when we apply current to it, the rise in current will initially induce a 100X current in the secondary. Once that current is flowing, however, since there is no change in current, the induced current in the secondary will die out (because the magnetic fields are not changing).

However, if we suddenly stop the current applied in the primary coil (in our case by opening up the grounded side of the primary coil using the points in the distributor) , the coil will try to prevent this change. Now remember we have opened the circuit (by opening the points), and so the flow of current is stopped. But the coil is going to try to prevent the current from changing. The only way it can do this is to increase the voltage. Remember Ohm's law states that V/I=R, and the resistance of the coil didn't change, so if I goes to zero, then V must go to infinity (or some practical version of infinity).

By opening the points, then, we have caused the voltage on the primary to rise to some high value. Of course there is only finite amount of energy stored in the inductor, so it can't sustain this indefinitely. What we end up with is a momentary voltage spike of about 300 volts.

Now, remember that the primary was intertwined with the secondary winding of the coil, and the ratio of turns was about 100:1. What this means is that the 300 volt spike on the primary will get amplified by the transformer property of the coil to about 30K volts. Since the secondary is connected (via the distributor cap) to a spark plug, this 30K volt spike will jump across the spark plug gap causing a spark.. And you know the rest of the story from there.

 

[HB Chris]

Scott, The 12:00 terminal on the starter would send 12v to the coil bypassing the ballast resistor only when cranking. New starters I have found are always hot so if you hook them up the ballast can turn cherry red!

 

[Patton]

Any luck over the weekend?

RP

 

[e9Leveque]

Any luck over the weekend?

RP

Didn't have any time, was out of town. I was also waiting on a new blue Bosch ignition coil, since it sounds like that might be a better overall option than the MDS Black that I have. Will allow me to remove the ballast resister and just hook up to the Pertronix. That coil arrived today but I'm still stuck at work for the next 2 hours and then have a 30 minute bike ride home, so we will see whether this is a job that has to wait until tomorrow. I'll update with success (I hope) or failure (perhaps more likely)

 

[Patton]

Good luck, i’m betting that you have found the problem. At least I hope that’s the case.

It’s always puzzling how it runs before you took everything apart and then it doesn’t when it’s reassembled.

RP

 

[rsporsche]

if anybody needs a new Bosch blue coil, i have one in a box that i bought from Korman in the early / mid 90s - never used.