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jack 6128
Dodge Dakota
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10/24/2011
20:50:16
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 Subject: Coil on 87 Dak V6 - occassional stalling
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Hi, all, don't get here too often, but this is my go-to place when I need advice to keep my 25 year old Dak running like new. The shop manual specs a coil that has a 9000 to 12200 ohm secondary winding. I have two replacement coils that I bought at Kragens over the years. One reads about 6500 ohms in the secondary and the other reads about 8100 ohms. Both read about 1.5 to 1.6 ohms in the primary. The 8100 ohm coil is branded "Select" and has "Use with external resistor" printed on it. I just noticed that today. The 6500 ohm coil is probably more than 15 years old and I replaced it with the 8100 ohm coil at least 5 to 7 years ago at a time when I was trying to deal with some aggravation or another in the ignition system. Both seem to work okay but lately the engine has been stalling infrequently while driving in traffic but not on the highway. The engine always starts right back up when this happens. I figured it was time to check the ignition system.
The last plugs I put in were platinums. After reading up, I decided to switch them out for regular Champion Copper Plus plugs. I checked resistance on all the spark plug wires and they are fine, about 10,000 miles on them. Cap and rotor have less than 5,000 miles on them and they look fine, gave then some light sanding with 600 grit paper. Which brings me back to the coil.
I know there is no ballast resistor on this Dak, so I'm not sure why it was printed on the 8100 ohm coil to use one. The primary on that coil is within specs, 1.5 to 1.6 ohms. I read today that you shouldn't use a coil that specifies a ballast resistor without one. And the other coil is way below specs on the secondary. So I found one at Rock Auto that is within specs on both windings and doesn't spec to use a resistor.
I am hoping that switching back to copper plugs and installing a properly specked coil will alleviate the stalling problem. I am guessing that perhaps the spark was too weak under certain conditions due to higher resistance of platinum plugs and lower secondary resistance in the coil resulting in lower voltage across the spark gap.
Any thoughts?
Jack
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Bob Lincoln
Dodge Dakota
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10/25/2011
08:54:34
| RE: Coil on 87 Dak V6 - occassional stalling
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Message:
Have you checked fault codes?
http://www.allpar.com/fix/codes/index.html
Sometimes the TPS can cause this without tripping a code.
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jack 6128
Dodge Dakota
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10/25/2011
11:22:21
| RE: Coil on 87 Dak V6 - occassional stalling
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Bob, this is an 87... it doesn't have a TPS and its OBD is primitive and requires an obsolete proprietary code reader that is as rare as a two-headed goat.
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Bob Lincoln
Dodge Dakota
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10/25/2011
16:14:49
| RE: Coil on 87 Dak V6 - occassional stalling
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That's right, unless it was a very late 87 it's carbed.
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yeah
Dodge Dakota
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10/27/2011
11:21:00
| RE: Coil on 87 Dak V6 - occassional stalling
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Is this motor carb or TBI ????
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jack 6128
Dodge Dakota
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10/27/2011
12:41:12
| RE: Coil on 87 Dak V6 - occassional stalling
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Carbed, original was Holley 6280 with mixture control solenoid, which is no longer available as a replacement part, so I replaced it with the 2280, same except for no mixture control solenoid
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OK
Dodge Dakota
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10/27/2011
14:27:50
| RE: Coil on 87 Dak V6 - occassional stalling
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Hows the fuel pump and filter?
Do you know if that Holley has the "Hard" filter
mounted just behind & inside the fuel inlet?
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cap
Dodge Dakota
JOIN HERE
10/27/2011
22:02:18
| RE: Coil on 87 Dak V6 - occassional stalling
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jack 6128, you may have a bad Hall Effect sensor. This is the piece just beneath the rotor in the distributor. These are frequently the cause of periodic stalling in Dakotas.
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jack 6128
Dodge Dakota
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10/27/2011
23:35:55
| RE: Coil on 87 Dak V6 - occassional stalling
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"you may have a bad Hall Effect sensor"
I had a bad Hall Effect sensor years ago that caused the engine to die while driving and I would always have to wait 5 to 15 minutes before the engine would start again and replacing the HE sensor solved the problem. Not so this time. When the engine dies now, it starts back up immediately without even a cough so I'm suspecting something else
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Curly
Dodge Dakota
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10/29/2011
11:00:29
| RE: Coil on 87 Dak V6 - occassional stalling
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Message:
The symptoms you describe could also be a loss of
fuel pressure.
Check it out to eliminate the possibility.
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jack 6128
Dodge Dakota
JOIN HERE
10/29/2011
12:59:55
| RE: Coil on 87 Dak V6 - occassional stalling
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I received and installed a new coil which has the exact resistance specifications in the primary and secondary that are in the shop manual and replaced the platinum plugs with the copper ones also specified in the shop manual. Since the problem is/was intermittent, the only thing I can do is drive as usual and see if it continues to stall.
If it stalls again, I will replaced the HE pickup in the distributor with a spare good one. If that doesn't fix it, I will check the fuel pressure.
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jack6128
Dodge Dakota
JOIN HERE
11/11/2011
12:08:52
| RE: Coil on 87 Dak V6 - occassional stalling
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The stalling problem seems to have been caused by an overheating coil that needed to be used with a ballast resistor. I bought a replacement coil from a big auto parts chain store years ago and just popped it in. Turns out that it needed to be used with a ballast resistor, which was printed on the coil and which I didn't notice at the time.
Fast forward many years later to the time of posting the origanl message in this thread. I bought an Airtex coil from Rock Auto that had the correct resistance in both primary and secondary, but when it arrived it had "Use with external ballast resistor" printed on it. I tried using it without a ballast resistor and it overheated and the engine stalled. When the engined stalled with this new coil, I checked for spark and there was none so I swapped out the new coil with a non-ballast resistor coil that I carry in the truck and the engine started right up. I thought the secondary on the coil might have blown, but when I checked it with a meter, it was okay. Later, I reinstalled the new Airtex coil and put a .5 ohm ballast resistor in line with the +12 volt wire and it ran just slightly warm after several miles on the freeway, as did the resistor, and no stalling so far.
This seems to point to the coil, but the Hall Effect pickup may still at fault. When the original went bad many years ago the engine would stall while driving and would restart after 3 to 15 minutes. Installing a new HEP solved this. This may have been what happened this last time, and enough time had elapsed while I was changing the coil for the HEP to kick in again. Only time will tell. If it stalls again I will change the HEP.
One thing that I am not sure about is whether a coil can fail from overheating and then recover, as this Airtex coils seems to have done. I don't see how this can happened unless there is a heat sensitive breaker inside the coil that resets when cooled.
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