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Discussion Starter #1 (Edited)
The intermittent nature of this makes diagnosis difficult. Hopefully someone can shed a little light.

'83 GTV6. Car will start and run fine. Next time I try, it cranks and sounds like it wants to fire but does not. This can happen the same trip. I drive to the store and then won't start when time to leave. Sometimes it just has to sit awhile other times I pull a plug to check spark, find spark, put back together and it fires right up. Or I check distributor cap, and upon reassembly it starts.

I've replaced fuses, checked connections that I know of, and replaced cap and rotor.

I've read of the Hall Effect sensor in the distributor. Could this be a culprit? I believe mine to be the 2 wire variety. Here are a couple of pictures. Check out the wiring on the green wire plug.

Thank you
Scott in MN
 

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In a perfect world you would use an oscilloscope to check the reluctor signal at the ignition control module, preferably while wiggling that connector and comparing the pattern in the start vs no start condition. Since most people do not own a scope, it would be difficult to directly check the reluctor output, but you can use a voltmeter and test light to check most of the ignition circuit.
 

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Discussion Starter #3
First, I apologize for my initial attempt at posting photos. I cleaned that mess up.

I now realize that my '83 has a 2 wire Variable Reluctance sensor and not a Hall Sensor. I'll detail the wires at the distributor sensor and the ignition control module.
 

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I just re-read your post. It is certainly possible that you have a vapor-lock issue when the engine is hot; an ignition issue is usually go or no go. You would need to connect a fuel pressure gauge to verify this. If the fuel pressure drops to zero quickly after engine shutoff, you have an issue with either the fuel pressure regulator, fuel pump check valve, or possibly fuel injectors/cold start injector leaking down. A huge cloud of fuel smoke out of the tailpipe after the engine does start would be a good indicator of leaking injectors.

As for ignition system testing:
If you have a good multimeter such as a Fluke and set it to read AC voltage, you might be able to get a flash of a signal at the distributor reluctor with the plug disconnected, then see if you get a similar thing to happen at the ignition control module. Not a super accurate test, but worth a try. A good test light will be able to catch the digital switching signal output from the ignition module to the coil negative terminal; again not as good as a scope, but no flashing equals nobody home.

A good digital timing light is also a good quick check of the secondary ignition circuit---clip the clamp around the coil secondary wire when you have a crank/no start condition, while the test light is also hooked up. Then you can isolate whether it is a problem with the primary ignition circuit, coil, or secondary ignition circuit. The original Bosch coils are incredibly durable, as are the ignition control modules, but either could overheat and drop out. Many cheaper modern replacement ignition coils (including the Brazilian-made Bosch ones) are complete junk and always a suspect in these conditions . . .
 

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VR sensors are very robust. If there is a problem it is more likely in the connector or the associated wires. They are however dependent on a consistent gap to the rotor.
 

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VR sensors are very robust. If there is a problem it is more likely in the connector or the associated wires. They are however dependent on a consistent gap to the rotor.
Agreed, that type of distributor reluctor does not tend to fail (have not seen it myself). The connector certainly looks suspect, however :).

The VR crankshaft and reference mark sensors as used in '80s Porsche 911, 944, BMW E30, etc with early Bosch Motronic fuel injection systems certainly do fail, but they live in a relatively harsh environment, and the adjustable sensor brackets lead to the opportunity of one setting the gap incorrectly.
 

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My experience, same symptoms exactly. Clogged fuel filter, I guess contributing to vapor locks / low fuel pressure. Whatever, after I replaced it never had another issue.

Only mentioning as no one ever seems to mention this as a possible cause / contributor.
 

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My experience, same symptoms exactly. Clogged fuel filter, I guess contributing to vapor locks / low fuel pressure. Whatever, after I replaced it never had another issue.

Only mentioning as no one ever seems to mention this as a possible cause / contributor.
Interesting. A clogged fuel filter usually causes issues at higher load when the engine demands a greater volume of fuel, but I would never talk anyone out of replacing it. Did you do any other fuel system work at the same time as the fuel filter replacement?
 

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Discussion Starter #9
Thanks for the ideas. I wouldn't think it was vapor lock as the symptoms can occur with a cold engine. Won't start at all or starts and then dies backing out of garage. I had my injectors tuned up by the OK Injectors back in '13. Fuel filter is ~20K miles old but I could still replace it. Symptoms began last year after installing a new water pump/timing belt. Car had sat for 4 yrs prior to that while I built a new house.

How about the Ignition Control Module itself? I found some great posts dealing with it. I picked up a used Bosch 227 100 123 last night that I'll try when it arrives.
 

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Interesting. A clogged fuel filter usually causes issues at higher load when the engine demands a greater volume of fuel, but I would never talk anyone out of replacing it. Did you do any other fuel system work at the same time as the fuel filter replacement?
No, just that. I did cut the old one open though, out of interest. yuk!
 

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Thanks for the ideas. I wouldn't think it was vapor lock as the symptoms can occur with a cold engine. Won't start at all or starts and then dies backing out of garage. I had my injectors tuned up by the OK Injectors back in '13. Fuel filter is ~20K miles old but I could still replace it. Symptoms began last year after installing a new water pump/timing belt. Car had sat for 4 yrs prior to that while I built a new house.

How about the Ignition Control Module itself? I found some great posts dealing with it. I picked up a used Bosch 227 100 123 last night that I'll try when it arrives.
Ah. In your first post you mentioned driving to the store and coming back out and the car won't start, etc, so I interpreted that as a warm starting issue.

I roughly described how to quickly check the ignition circuit in my first post (there are more comprehensive guides out there), might want to do that before replacing parts. But, yes, the ignition control module could be the problem. The reluctor in the distributor generates an AC voltage with a sine wave pattern, which goes to the ignition control module. The control module converts this signal to a digital square wave and sends it to the negative (terminal 1) of the coil. You can catch this switching signal with a test light.

But that connector at the distributor is also suspect. It gets a bit tricky with that as the ground is shielded, so standard wiring repairs will not work. I'd check the basic of the ignition circuit when it acts up and go from there . . . .
 

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How about the Ignition Control Module itself? I found some great posts dealing with it. I picked up a used Bosch 227 100 123 last night that I'll try when it arrives.
Does your car run the original 0 227100 117 alloy box ignition module? now if you want to replace this module with a Bosch
0 227 100 123 / 111 you will need an ev1 7pin male connector and will need to wire it as follows

The ignition module 0 227 100 111 will work as a direct replacement for the alloy cased 0227 100 017.
I have swapped mine over, My car has the two-wire VR inductive pick-up distributor. I used the module from my written off ALFA75 which has the three wire hall effect pick-up. It works perfectly with no over-heated coils, poor performance or misfires as long as you have the whole ignition system correctly wired.
My alloy box 0 227 100 017 amp had these colored wires they connect to the 0 227 100 111 as follows.

black/white.......................................connect to #1
black...............................................................#2
green/black .....................................................#4

The 2 wires From the distributor are as follows
green and shield

green...............................................................#5
shield...............................................................#3
#6 and 7 are not used
You can use a BOSCH 0 227 100 111 a Tridon TIM 017, Fuelmiser CM413 or a BERU ZM 001 as a direct replacement for the 0 227 100 017 alloy box.
You will need a Bosch EV1 7 pin male connector. No other parts need to be replaced or modified.
The original post is here
www.alfabb.com/bb/forums/engine-management/592073-bosch-ignition-modules-milano-gtv6-2.html#post8479308
 

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Rather than guess and replace try some systematic troubleshooting.
Mark the position distributor then remove it. With ignition ON, spin the distributor and listen for clicking of the injectors and sparking of the plugs. That should enable you to narrow down the cause of the problem before you start swapping things out.
 

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