Pertronix upgrade - Page 3 - PeachParts Mercedes-Benz Forum

jester69 · #31 04-19-2006, 01:09 PM

Quote:

Originally Posted by Arthur Dalton

Kinda hard place for a new guy to come into telling guys who have been BenzsHeads all their life how these systems operate...

Thanks for the welcome.

I have more VW knowledge stuck in my head than should be allowed for one person. That translates into a lot of knowledge that applies to mercedes, and just as much that doesn't.

Pertronix are a very common upgrade to VW's so I should have known my stuff there. Not being perfect, I goof every now and again.

In general, Ignition is ignition more or less. I should have kept my mouth shut about what the benz systems do, I don't really have much of a clue there and should try to remember that.

take care,

Jester

ADow · #32 05-02-2006, 08:31 AM

I'm still staring at my useless Pertronix system

- my next thought is to contact Pertronix directly with my problem. The technical support module of their corporate website is still under construction and there is no contact email on their site. Adelaide South Australia is a long way from San Dimas California so I can't just wander down to the factory for a yarn. Does anyone have an email contact address for Pertronix?
Many thanks
Alastair

Arthur Dalton · #33 05-02-2006, 09:29 AM

Reading your posts, the Pert. module is suspect. If you have at least 12v at the coil + along with the red wire from the Pert, and the black wire from Pert on the neg side of the coil , the only other possible would be no ground.
That can be checked by using an ohm meter by checking resistance across the grounding plate the module is screwed to in the distributor and the battery neg terminal.. you shoud have trace resistance there , verifying a good ground.

So, if you have both 12v and good ground at those two points, the module should then be tested ..
This test is for the Ignitor 1 , not 2..

http://www.ttalk.info/Tech/PerNegGndTest.htm

http://www.vintageperformance.com/retrorockets/troubleshooting.htm

After looking at these , this will help you in understanding how the Pert really works.......
12v is supplied to the module to power the modules circuitry. This must be 12v , as lower voltage here will not be sufficient to trigger the Pert. This comes from the ignition sw , via the coil pos.+.. When the rotor/magnet passes by the module , it sends a trigger current/signal [via Hall Effect princible] to the modules contained circuitry, which then GROUNDS the black wire going back to the coil. That completes the coils primary circuit and as soon as that circuit opens back up,
[ via the magnet moving away from the module],you get secondary spark at the coil..just like points , but with no Mechanical switching. So,...what you have is called a SWITCHED GROUND .. which is why the unit will not work if you have a Bad/No Ground.. just like it will not work if the module does not have 12v + feed from the ignition switch....
That is all the Perts. funtion is .. to GROUND the Black wire [ coil neg] everytime the magnet passes the module. [ You can actually make a Pert trigger with a standard magnet.]
If you just grounded that black wire intermittantly by touching it to ground manually, the coil would put out a spark from it's secondary tower every time you touched ground. Same deal, only this grounding of the coils neg side is controlled via the Perts. grounding circuitry...........

ADow · #34 05-03-2006, 09:33 AM

Thanks for the test Arthur (and your persistence!) - It seems simple enough and saves me sending it back to Melbourne to be tested by the supplier. Will do it soon before attempting another installation.

With regard to checking that the module plate is grounded you say "That can be checked by using an ohm meter by checking resistance across the grounding plate the module is screwed to in the distributor and the battery neg terminal.. you shoud have trace resistance there , verifying a good ground". I need a little more help here (you are dealing with someone with limited understanding of the basic principles of electricity - I have been thinking that continuity between the module plate and the distributor body indicated that the module was grounded).

I have a multimeter which measures resistance. Is your advice to install the module into the distributor, and then to check the resistance between the module plate and the negative terminal. What is 'trace resistance'? If there is not 'trace resistance' what should be done?

Arthur Dalton · #35 05-03-2006, 10:17 AM

>>I have a multimeter which measures resistance. Is your advice to install the module into the distributor, and then to check the resistance between the module plate and the negative terminal. What is 'trace resistance'? If there is not 'trace resistance' what should be done?
>>

Ok
*trace: - a very slight detectable amount..almost zero.*

...and Yes, reinstall the unit for both this ohm test and the module switching test ......

If you Zero your ohm meter in by connecting it's leads together, it will show Zero ohms [ your meter may be self zeroing]
TRACE resistance means almost NO resistance..[less than .2 of an ohm.],
just like when you put the meters leads together. This is an indicator of good continuity. [ lacking resistance]

The reason you test to the Neg of the battery is b/c this is where the ground of the cars electrical sytem comes from...so, if there is good continuity [ trace ohms] between the distributor plate and the battery neg, you are assure of a GOOD ground..however, if there is resistance between that plate and the bat. neg, you have a distributor that is not grounding well OR you have a bad ENGINE ground between the engine block and the battery neg.. that can be caused by a bad engine grounding strap,,which will effectivly show up on the Pert as a bad ground [ incomplete circuit], thus no spark, even with a good module

The Rert NEEDS a GOOD ground to make a complete circuit to the coils primary windings.

Another test with the meter is to take a reading from a good engine ground [ on the block somewhere] and the bat neg post... if there is resistance on this test, you know you have a bad/poor engine grounding strap..same test, but you are now isolating a possible cause. Same goes for the distributor...there should only be trace ohm between the dist. plate and the engine block.. resistance
here would tell you the dist is not making a good contact where it mounts to the engine..[oil/dirt/loose. etc.].. you can now see how one can check where a bad ground occurs....an easy rule is any parts between your leads test points should show good continuity on any ground check.

* An added note:
For any DC electrical circuit to function , it must be a complete circuit loop through the Pos and Neg bat. terminal.. so , a bad/poor ground is just as bad as a poor 12v pos feed.. either will cause low voltage or if really bad , an incomplete circuit...so, always check for bad grounds on auto circuits ..
they are more common than most think..........

Again, in your case, I suspect the module, but I mention the ground test b/c it will show the same failure as a bad module, so I would check that first just so you do not go chasing around...

ADow · #36 05-07-2006, 03:55 AM

Tested the module today. Rotating the magnet in front of the unit gave a reading between 0.01 volts and 12 volts. So I am assuming that it is ok.
Also tested the continuity between the distributor and the negative terminal of the coil. Got a reading of 0.02.
Will attempt another full installation when I have a few spare hours and don't need the car. Is it strictly necessary to disconnect the 'cranking' ballast resistor?

nhdoc · #37 05-07-2006, 07:45 AM

Wow, this is really puzzling...are you sure you're pushing the magnet all the way down on the cam when you install it? It has to "seat" all the way down. The next step would be to test it on the car, after installing it and while cranking to see if it is switching. This would take two people, one to crank while the other watches the volt meter.

The only way I can think it would not work on the car is if the gap between the magnet and the module is too great, and I can't imagine why that would be unless the magnet is not pushed all the way into position or the distributor is not the correct, original model.
As for your question about the cranking lead...I assume you mean can you leave that lead attached to one side of its ballast resisitor and disconnect the wire from the other side of the ballast, yes, you can do that and just leave the ballast in position with nothing attached to the other end of it.

Have you measured the voltage from the +12V lead you are using to attach to the + side of the coil to make sure it is 12V?

We'll get this going, there's really not that much to it (usually)!

ADow · #38 05-07-2006, 08:57 AM

G'day Marty - will test it on the car as you suggest when I get some time and don't have to rush to put the old system back on - and yes, I am pushing the magnet all the way down and then firmly seating the rotor on top of it, and I have no reason to believe that the dizzy is not correct - I have bought new rotor and dizzy cap for it and they fit and work. The gap between the magnet and the Ignitor looks about 05mm - 1mm when it is installed. (I'm guessing, but you can see daylight between the magnet and the unit). However, a test on the car will eliminate as a possibility that the unit and the magnet are not communicating.

With the original setup in place the 'switched' lead that runs through the upper ballast resistor is 12v on the ignition side of the ballast resistor and 7 volts on the coil side of the ballast resistor. But your question means that I will check that the switched line is actually getting 12 volts next time I install the Ignitor and disconnect all the other wires.

The simplicity and elegance of the Ignitor concept is very appealing and like all technical problems, there must be a logical solution to this one.

nhdoc · #39 05-07-2006, 09:03 AM

Hi Alastair,

That gap sounds to be right so I doubt that's the problem.

And when you wire the ignitor you use the straight 12V feed, right, and don't use any ballast resistors?

If you test the ignitor on the car and it passes then the fault must lie in the coil...what else can it possibly be???

Arthur Dalton · #40 05-07-2006, 09:49 AM

< >>

....that is not what I wanted you to test.. the ohm test needed to verify contunuity/ground is between the dist. plate and the neg terminal on the cars BATTERY...
Again the module needs 12v to power it, so you need a good ground back to the battery... and no resistors going to the red wire for the module..that red wire has to have 12v , pos +

ADow · #41 05-07-2006, 10:12 AM

[QUOTE=Arthur Dalton]< >>

....that is not what I wanted you to test.. the ohm test needed to verify contunuity/ground is between the dist. plate and the neg terminal on the cars BATTERY...
QUOTE]

Noted - Will do so next time I install it properly. I bypass the ballast resistor that normally feeds the coil when I install the Ignitor.

Arthur Dalton · #42 05-07-2006, 10:14 AM

Very Good........

ctaylor738 · #43 06-12-2006, 04:07 PM

What finally happened?

ABDow · #44 01-23-2007, 05:30 AM

This is the way that I (with the able assistance of a passing German electronics teacher) have made the Igniter work in my m116 3.5.
http://members.ozemail.com.au/~adow/Ignitor.mht

How to install a Pertronix Igniter 1 (part number 1885) in an M116 3.5 V8 (with earthed coil).

#1. Disconnect and remove the points and the condenser from the distributor.

#2. Disconnect the wire that connects the points to the Mercedes electronic ignition unit.
It’s a green cable with two concentric wires, one earthed to the outside of the distributor and the other connected to the points.
It’s connected to a terminal just below the Mercedes electronic ignition unit.

#3. Install the Igniter in the distributor as described in the Pertronix instructions and extend the black and red wires by about 30cm each, long enough for the red wire to comfortably reach the lower 0.4 ohm blue band ballast resistor.

#4. Disconnect the brown earth lead from the negative pole of the coil and leave it disconnected.

#5. Connect a bypass wire from the ignition side of the lower 0.4 ohm blue band ballast resistor to the ignition side of the upper 0.6 ohm silver band ballast resistor.

#6. Attach the red wire of the Igniter to the ignition side of the lower 0.4 ohm blue band ballast resistor.

#7. Attach the black wire of the Igniter to the negative pole of the coil.

#8. Run an earth wire from the Igniter base plate to the negative pole of the battery – this will ensure that the Igniter is properly grounded and is a critical step.

#8. Reset the ignition timing.

picture# 1. Diagram of original ignition system

picture# 2. Diagram of ignition system with Igniter installed

Thanks to Arthur Dalton whose advice months ago about grounding the Igniter with a wire to the negative pole of the battery was crucial to solving the problem.
Alastair