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Discussion Starter #1
The resistance spec for a GTV6 coil is:
  • Primary coil: .7 to 1.2 ohms
  • Secondary coil: 6.9 to 11.9 ohms
My primary coil reading is 1.5 ohms and secondary is 6.85 ohms. I can poke things with my multi-meter, but I don't have a good sense of the meaning of relative readings. Is 1.5 ohms, which is .3 ohms out of spec, a big deal? Could it be enough to cause a sudden loss of spark as described here: http://www.alfabb.com/bb/forums/alfetta-gtv6-1972-1986/401233-gtv6-idles-better-o2-sensor-disconnected-2.html#post6136145 ?

If this isn't enough to cause sudden loss of spark, then other potential culprits are:
  • The POS connector to the inductive pickup on the distributor
  • The ignition module (located below the coil)
Is there any method of testing these two items?
 

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I look at coil specs as either in or out. Close only counts in hand grenades and horseshoes. Having said this, it's been my experience that coils and modules fail when they get hot. Either hot internally from their operation or hot from their environment. Ideally you'd be able to test them at operating temps. I'd bet your specs change a bit.

ADDED: I read your thread referenced and think you have an ignition issue as well. One thing that aids in diagnosing is to run the engine in the dark and see what you can see as far as leakage goes. Old school yes but very effective and might identify something. I found bad plug wires by using this method on the 164. They "tested" OK. Reading your thoughts, I'd be inclined to look at the dizzy and it's condition - bearings and such for looseness. The module for sure and all related connections/grounds.

I went thru this drill on my Milano recently. It had a loss of crank from the switch that appeared when the car had been run and it was operationally hot. Cool it down and it would crank/start. Few weeks later it lost spark from the coil. It was running and just died. Deader than the proverbial door nail. I was pretty sure the ign switch was going south so I decided to change a bunch of stuff cause I could, the parts were cheap and they were 25 plus years old and could stand renewal. The module could not be tested and I'm not sure I'd trust the results from testing a cold module anyway. The pick up should be changed as course of module replacement I believe, and I wanted the dizzy rebuilt so it had to come apart anyway. I know of no way to test a pick up except checking for continuity.


Module, pick up in the dist. The coil was a new Blaster 2. I tried the old/still good coil with the same result. Still no spark. Ran a jump from the batt to the coil and vroom. So either the ign switch or the wiring to the coil. I had planned to bypass the switch this spring anyway so why not now. My euro bets its the ign switch in my case. best of luck, ciao jc
 

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A coil works or it doesn't. Resistance measurements vary, because of the quality of the meter used to measure these values. If they are close it's good.
I had a strange problem with my Milano this winter, and you may want to check this out. I was having the same issue and found that one of my Spark Plug wires were bad. The plug side was good, cause I changed the plugs, but one of the wires on the coil side was totality wasted, even though it may look good, I would check your wires at the coil, by physically removing them and inspect them.
 

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The resistance spec for a GTV6 coil is:
  • Primary coil: .7 to 1.2 ohms
  • Secondary coil: 6.9 to 11.9 ohms
My primary coil reading is 1.5 ohms and secondary is 6.85 ohms. I can poke things with my multi-meter, but I don't have a good sense of the meaning of relative readings. Is 1.5 ohms, which is .3 ohms out of spec, a big deal? Could it be enough to cause a sudden loss of spark as described here: http://www.alfabb.com/bb/forums/alfetta-gtv6-1972-1986/401233-gtv6-idles-better-o2-sensor-disconnected-2.html#post6136145 ?

If this isn't enough to cause sudden loss of spark, then other potential culprits are:
  • The POS connector to the inductive pickup on the distributor
  • The ignition module (located below the coil)
Is there any method of testing these two items?
The resistance measurements you are measuring are perfectly OK, the slight difference could be your meter is not calibrated lately.

However even a good measurement at state cold does not ensure against loss of contact in coil when warm. I have experienced coil cut out when warm and it came without pre warning at high revs and loads. Only problem is that one has to realise that the fault could be that the coil can lose contact when warm! Easyest is to change coil and see, quite cheap item to change!

GK.
 

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Coil resistance measurements can tell you what kind of coil you have but not how good it is. You need a high voltage insulation tester for that.
 

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Discussion Starter #6 (Edited)
Thanks for the input everyone. I actually have new plugs, wires, cap and rotor. Unless I got something bum in that batch, should be able to rule those out.

So I think that narrows it down to coil, ignition module, POS connector at distributor or the distributor itself. Or a stray wire/connector arcing somewhere, which would be troublesome.

Given that this only presents when the car has been running for a bit and is plenty warm, I am still leaning toward coil. But I am a proponent of just doing like things "while I have the hood up". All the stuff above is 30 years old. I am thinking of just replacing it all to keep it from failing later.

Is there any reason just replacing all the above would be a bad idea? (e.g. new parts aren't as good as the OEM stuff, etc.)

Also - is there any significant difference between using an OEM Bosch coil versus after-market coils from Standard or Airtex on these cars?
 

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I'd change it all. I run MSD Blaster 2 coils in both my Alfas, no problem. The Bosch coils for my Twin Spark 164 are 400 or so for the pair!! Gubi recommended the MSD and I took his advice. 80 bucks for the 2 my car requires. I've run Bosch Blue coils as well without issue on past Alfas. On my 75, I went with a Facet pick up and another brand for the module I cant remember the name of. They both work well. The Bosch module was 120 euro vs the 20 for the one I got. You can see why...

ciao, chris
 

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Thumbs up for Blaster coils. Thumbs down for Bosch Blue coil in this application.
 

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Discussion Starter #10
A few remaining questions:

#1 - The MD Blaster2 Coil actually has a secondary resistance of 4.5K ohms. Alfa spec calls for 6.9 to 11.9 K ohms. Is this OK as a replacement coil?

#2 - Which end of the POS connector on the distributor usually goes bad? The electrical lead end coming from the wiring harness or the distributor pickup side? If the pickup side, then is this a suitable replacement: Amazon.com: Wells RB115 Distributor Ignition Pickup Coil: Automotive. I see nothing on IAP's site for the part.

#3 - I am seeing lots of ignition modules out there for $25. For example: Amazon.com: NEW IGNITION CONTROL MODULE FITS ALFA ROMEO BMW CITROEN DAIMLER BENZ PEUGEOT TALBOT 116976507901 705786 12-14-1-266-702 12-14-1-273217: Automotive. IAP is charging $68. Any idea if the IAP module is of a higher quality or are all these things essentially the same?
 

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The secondary resistance has no effect on your choice but primary resistance is important. Lower primary resistance = more current = more spark energy. Some triggers will not handle a higher current and they must use higher resistance, lower current coils like the Bosch Blue. I would choose one in the 0.7 to 1 ohm range for your car.
 

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Yeah, the Blaster 2 has a 0.7 Ohm primary resistance, which is in-spec for the L-jetronic system. It'll work fine.

The electronic ignition trigger isn't hooked up to the secondary windings...those just go to the spark plug.

Usually the connector side that plugs into the socket is where things go bad on the distributor. You shouldn't need to replace anything: just make sure the wires are well insulated and not shorting to each other, that they're tightly attached to the terminals, and that the terminals on the connector fit snugly into the socket.

Like I said, if this is actually your problem over bumps, you should be able to replicate things by wiggling the wires.
 

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Discussion Starter #13
Thanks for the advice all - that'll get me moving forward on this.
 

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I'm not sure if this'll apply. When I was searching out the module here in Italy for the 75, the Bosch had either one more or one less terminal than the replacements we were finding. I dont recall the sequence and dont have access to the old one at this time. The parts guys assured me it was a good cross and plugged in directly and functions a treat.

Then a few days later, my CarDisc arrived and I spent alot of time studying the diagrams and came to the realization that the module in my install is very, very simple in its wiring and function. I had always understood it to be an on/off switch for the most part and these diagrams shed light on this.

The reason I bring this up is that being sure of what you have and what you get/want is important as I doubt it can be returned. The blasters I get from Summit Racing. I doubt IAP is the only game in town as these modules and such work on alot of differing cars. One thing chasing parts here in the motherland has taught me and continues to hammer home is the interchangeability from one maker to another. I'll try and find a pic or 2. ciao jc


Added: found some pics. I didn't have tools to get the distributor apart where I needed it to be apart so I had a shop I know do it and clean the guts out of the old grease and such. I dont believe my pick up was "bad" but I was trained if yo replace the module, replace the pick up. Anyway just cleaning and regreasing the dizzy paid enormous dividends. In the upper pic, the pick up is still mounted and the new one is in the pic as well. The 2 tips coming out are what hook to the connector on the side of the dizzy. Issue I had was getting the reluctor to come off the shaft without messing something up. Well worht the 20 euro I paid for the work.
 

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But Mad North-Northwest
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I'm not sure if this'll apply. When I was searching out the module here in Italy for the 75, the Bosch had either one more or one less terminal than the replacements we were finding. I dont recall the sequence and dont have access to the old one at this time. The parts guys assured me it was a good cross and plugged in directly and functions a treat.
IIRC there are versions with 6 pins and 7 pins. The Milano uses the 6 pin version, but the many of the 7 pin ones should work since the 7th pin just is not needed on the Milano and is just ignored.

I forget the exact details, but the takeaway is that the amplifier module for many other cars (but maybe not all) will work fine in the Milano. Try doing a web search, as there's a lot of info out there about this component and the cross-references.
 

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Discussion Starter #16
Just closing out this thread. The coil was my issue. Now fixed. :)
 

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I have similar issues. Car starts and runs fine, gets hot, starts misfiring under throttle, eventually stalls, won't restart until it's cooled significantly, rinse and repeat.

MSD Blaster 2 is $46 on Amazon Prime.
http://www.amazon.com/MSD-8202-Blaster-Hi-Performance-Coil/dp/B000182BDK/ref=sr_1_1?s=automotive&ie=UTF8&qid=1432310432&sr=1-1&keywords=msd+blaster+2

$7 more with the ballast and boots.
http://www.amazon.com/MSD-8203-Blaster-Hi-Performance-Coil/dp/B00029JKIM/ref=sr_1_2?s=automotive&ie=UTF8&qid=1432310432&sr=1-2&keywords=msd+blaster+2
 
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