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RenaissanceMan

Chasing down tii running problems... Coil dying?

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Had the tii running really great after setting dwell and timing. Drove it for several miles and then it started missing intermittently and not pulling as strong. Got home and double checked dwell and it looked fine. Then had trouble starting the car. Occasionally would start if I assisted with the accelerator pedal, but it would no longer hold an idle. Now when I monitor dwell with my meter, it is erratic. Reset dwell several times trying to chase it down. Bench tested the coil with an ohm meter and primary and secondaries were in spec. However, my dad had an issue on his e24 once where the car would run amazing until it got really hot, and then would die and not start again. Wondering if I have a failing coil. Brand new wires, points, rotor, cap, condenser. Have a mechanical advance dizzy and running older black coil with no ballast resistor. FWIW it is 89 degrees today and I drove the car hard to get her heated up pretty good.

 

Right now letting the car cool and then going to see if the symptoms go away, but I wondered if there could be anything else I'm missing? Could I have a failing dizzy?

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You need the ballast to drop the voltage to the coil. Change your coil to a Bosch blue one and you will be fine.


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19 minutes ago, Dudeland said:

You need the ballast to drop the voltage to the coil. Change your coil to a Bosch blue one and you will be fine.


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The old coil was for use without a ballast, as is indicated on the coil, but i had ordered a new blue coil and it just arrived today. Will be testing tomorrow if the weather holds out and will report back!

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i would revert to the old condensor...modern parts are really unreliable

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"....running older black coil with no ballast resistor"

 

^why no ballast resistor?

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(edited)
39 minutes ago, RenaissanceMan said:

The old coil was for use without a ballast, as is indicated on the coil, but i had ordered a new blue coil and it just arrived today. Will be testing tomorrow if the weather holds out and will report back!

 

Some experts will tell you that the original-original black coil uses a ballast resistor.  New tii (recommended) coils are red and use a ballast resistor.  Actually the coil label is more "inka".  Fine by me. :D

313730804_GaugesinEngine2.jpg.cfa536f1df114b6ede51ede3f44018d9.jpg

 

I've been scoffed at for using a blue coil and resistor.  Never had any issues (that I know of).

Edited by PaulTWinterton

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I’m about to order a new coil for my Tii, as the throat that accepts the HT lead to dizzy on my black coil is damaged, I am ordering the Bosch blue coil and it is advertised as working better with electronic ignition? I have the same sort of performance issues with mine as well at the moment. Watching with interest, do you need to do anything special swapping in your blue coil? 

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Just remember that the US cars are the ones that are mostly fitted with the ballast resistance ignition so you are looking for a coil with a primary resistance if about 3 ohms. 

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Ok thanks Simeon, was getting mine from Jaymic.

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1 hour ago, iinca said:

"....running older black coil with no ballast resistor"

 

^why no ballast resistor?

 

Ballast resistor was previously removed from my car. Here is the current. Pretty positive this was not original, but as you can see the resistance is not compatible with a ballast resistor setup: 

20190704_185035.jpg

20190704_185050.jpg

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10 minutes ago, SydneyTii said:

That looks like be beetle coil? 

 

Yeah it's a mystery to me. Even though primary and secondary resistance meters out ok, I still don't trust this thing. Bought the blue coil to at least start with a known compatible component and I will go from there if it doesn't fix the hot running condition. 

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Ballast resistor was previously removed from my car. Here is the current. Pretty positive this was not original, but as you can see the resistance is not compatible with a ballast resistor setup: 
20190704_185035.thumb.jpg.badc735b8345543ace923d53a8e1eebd.jpg
20190704_185050.thumb.jpg.3efa7c4eb758811a4ff63c5f4bf27eaa.jpg

It has been a while but it looks strangely familiar.


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On 7/1/2019 at 11:59 AM, RenaissanceMan said:

Now when I monitor dwell with my meter, it is erratic. Reset dwell several times trying to chase it down. Bench tested the coil with an ohm meter and primary and secondaries were in spec.

 

What is the theory behind a bad coil causing erratic dwell?

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11 minutes ago, Chris_B said:

 

What is the theory behind a bad coil causing erratic dwell?

 

Honestly at this point I don't think a bad coil would affect dwell... It was just strange that I had that happening once the running problems started. I didn't update the post earlier, but when I monitored it yesterday with the motor cold it was no longer erratic. I think it is more likely my analyzer had a bad connection or something at the time.

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