Sparks cuts out when motor warms up-ballast resistor?

[john.thompson068]

This morning I had no spark. Then I used a test ECU and coil and still no spark. I bypassed the MSD ballast resistor. Still no spark. I put the old ECU and coil back on, reconnect the ballast resistor and go to buy a new battery. I come back and still no spark. I bypass the ballast resistor again and no spark. I hook the ballast resistor back up and all of a sudden spark.


I had spark for about five minutes. After the car warmed up to about 180 degrees the ignition starting cutting out and it lost spark. I noticed that the ECU was too hot to touch. I tried bypassing the ballast resistor and no spark.

Is it possible the ballast resistor is bad and is causing these problems? The ballast resistor is the MSD 8214 and is about five years old, but has very few miles on it. Maybe about 1500 or so. Car has MP electronic ignition kit.


A few things lead me to suspect the ballast resistor. One, it was the last thing I disconnected and reconnected before the car suddenly had spark. Two, I wonder if a failing ballast resistor might be overheating the ECU and causing it to quit working until it cools off.


The symptom here seems to be that when the car warms up or has been running about five minutes, it starts running all erratic and then loses spark.

 

[70rr-brian]

Usually when ballast go out the car will quit running when you release the ignition key from the start to the run position.

But bypassing the ballast should have at least got you started...maybe a nice burnt jump wire but at least it should have started if it was the ballast.

You sure your "test" ECU is good? Just wondering how it found its way to "test" status. In all the time that elapsed your old ECU could have cooled down to the point of being able to work again.

 

[john.thompson068]

The test ECU is a brand new one from Advance Auto used to verify that my FBO ECU was bad. I also have a brand new test coil from when my first FBO ECU went bad. I now have a brand new MP chrome ECU.

The chrome ECU never fired this morning. I was switching out the components and messing with the ballast resistor and all of a sudden it had spark with the chrome ECU and original coil. It ran for about five minutes before running erratic and then losing spark. The ECU was very hot, and this time bypassing the ballast did not give spark.

I am about to spend $12 on a new MSD 8214 from Advance, and if nothing else, then I will have a spare or test unit. Maybe by tomorrow night I can have the new ballast and check for spark.

 

[70rr-brian]

Sounds like you have an epidemic of bad ecu's...

You sure your wiring is not cracked up or otherwise in bad shape?

 

[john.thompson068]

No wiring is good and solid. Car has been a reliable daily driver for 12 years, although the last 2 years it has been garaged. I was driving it and it was fine. All of a sudden the my second FBO ECU was bad. Installed my test ECU and it had spark. I then purchased a chrome box and it was working up till today.


It is wired correctly. Car ran for 12 years and tens of thousands of miles on exact same wiring. I have since replaced the connectors on the ends of all my wires and soldered all of my connections for the ignition system about 4 years ago.

I do not believe it is another bad ECU because my other known good ECU also did not have spark this morning. Then my chrome ECU just had spark a little while ago. The chrome ECU is brand new and doesn't have any miles on it yet.

It is something before the ECU and coil, like maybe the ballast resistor dieing.

 

[67 B-body]

what kind of Distributor are you using? Could your pickup be bad? I would check to see if the - side of the coil is opening and closing to ground like it should be, and if using a magnetic pickup type ignition check the resistance through the pickup coil, and also check for good ground of the distributor body itself "some require this". The ECU has to have a good clean ground as well.
When electronics failing are heat related, I hear "current breakdown" and "high resistance"...
I wouldn't be suprised if the trouble is dist related... If the dist is telling the ECU to close the ground loop and never opening up the circuit it will get warm....

 

[john.thompson068]

I hope it is not going to be the distributor. The distributor is a fairly new component. I think it is the same one that came with my electronic conversion kit. I don't think I had to get a different one when switching from small block to big block motors. ECU has paint removed on firewall for proper ground. Actually, I had an orange box that lasted four years and tens of thousands of miles before I ever scraped off any paint. Also, the distributor has been fine just the way it is so I don't believe there is a ground problem there. I have no idea if the pickup is bad. It looked fine when I looked at it recently. I will have to wait on the ballast resistor and test it out on Friday or Saturday. Man am I glad I have a second car now! I am losing all confidence in the reliability of my car. It was my only car from the time I was 18 until I was 28. And to think that three times I swapped in an open 2.76 chunk, jumped in my ride, and drove all the way across country with no problems. Now for a while anyway I will be afraid to go further than I can pay for a tow :sad10:.

 

[67 B-body]

BB and SB dist's are different.
You dont have to have a Ballast resistor to measure resistance across the pickup coil, just put an ohm meter on the two wires that come out of the dist and note the reading. You might have to do this when it gets hot and shuts off as well, because heat increases resistance and could be killing it for you.
You can also measure the resistance on the ballast resistor you have to determin if it is faulty or not.

 

[74sundance]

Here is some trouble shooting info for no spark:

If there's no spark, First, check the voltage at the "+" side of the coil, which may also be marked "bat" or "ECU." It should be at least 8 volts with the key in the "run" position, and within a 0.5 volts of the battery voltage during cranking. If it fails the "run" voltage test, swap the ballast. On cars with the old-style 5-pin ECU, try the ballast regardless of the voltage readings.

Still no good? Meatball surgery time. Run a clip lead from the "+' side of the coil to the "+" side of the battery. It will start now, but you'd better drive home fast, as the coil and ECU (or points) will be taking a beating. Safely home, you can check the bulkhead connector, ignition switch, etc.

If the coil "+" voltage is correct, but there's still no spark, either the ECU or points, depending on what you have, is probably the culprit. For points, you can disconnect the distributor wire from the coil, and measure the resistance from the wire to ground. It should pulsate from zero to infinity as the engine is cranked. No? Take off the cap, crank, and check that the points are actually opening. A quickie eyeball adjustment will usually get you going, but points have been known to "grenade," rivets actually popping out, arms breaking off, etc. That's why you packed a spare set, right?

If you have electronic ignition, and brought an ECU, you're in like Flint. Of course, occasionally the ignition coil itself, as well as the distributor's internal mag pickup coil and/or it's leads, will fail. Such is life!
Above info is from: http://www.moparaction.com/tech/archive/roadside.html

http://www.fourforty.com/techstuff/ignition.html

http://www.nls.net/mp/volks/htm/spark.htm

http://waywardgarage.com/129/testing-an-automotive-12-volt-ignition-coil/

Hope this helps

 

[john.thompson068]

Well at least until I get the car running I can look at the awesome progress you have been making with your Sundance. I can't wait to see the rest of your pictures once you have it painted.

 

[Ron 73]

John, I posted in another thread about a related problem and what i found to be the problem, not what you want to hear but if you run out of options try replacing the pick up coil and reluctor, I dug this up just now and says about what i said so ill leave it for you to read and go from there, i know all to well what your going thru with this. Good luck, hope this helps...

"with a digital volt meter set to 2K ohms.... measure the resistance of the pick up coil.... you should get somewhere between 500 and 1,500 OHMs of resistance... you can do this at the distributer connector and again at the module connector.... before disconnecting.... flip the volt meter setting over to 2 volt AC or 20 volt AC scale.. spin the distributer shaft or have somebody crank the engine..... you need to see close to 1.0 Volt AC or the ignition module will not work...

this is an important test... both parts.. the ohm test and the ac voltage test... why....

with the ohm test.. you verify the pick up coil windings are intact...

with the AC volts test.. you verify that the reluctor is actually working.. they do wear out.. they can be damaged...

what... how... ???? the reluctor is made of a material that does not like to be cleaned... it does not like solvent... it can just wear out...

what it does... it retains a slight magnetic field as it spins past the pick up coil... when it cannot retain that magnetic field... it will not have enough magnetic field lines passing through the pick up coils windings to create the AC signal that turns on the power transistor in the module....


you can also verify that the distributer is working with it removed by grounding the distributer housing..... and spinning the shaft... the coil should fire like crazy...


the ohm and then the AC volt test work on any type of ignition with a pick up coil.... ford. gm...toyota..honda..

its an easy way to tell if the pick up coil is not just good.. but if the reluctor is working...

reluctors can fool you also.. as once in a while.. there is just enough voltage created to start the motor and the next time not...

be sure to note which location the pin is in.. the small blocks and the big blocks use the same reluctor.. but the distributers spin the other way... so there is a different location between the small and the big block applications.. if you get it wrong.. the rotor will not be pointing at a cap terminal when the coil fires...

something else... get in and examine the 3 ground connections....

battery to engine block ground...

battery to body ground...

engine block to firewall ground....


i like an engine block to module mounting bolt ground......

why all these grounds... its just a ground wire...

electrons flow from negative to positive...

if you don't have a ground wire properly attached.. you only have half the circuit hooked up...

will a flash light work if you don't put the cap back on to connect both ends of the batteries???


with a digital volt meter.. set to 20 volt DC scale... you may also have to test at 2 volt DC scale..

touch from the negative battery post to the engine block... have somebody crank the engine .. less than 0.5 volts while cranking is acceptable..

another test

engine block to the body or firewall near the module... less than 0.04 volts is acceptable..



if the engine runs... turn the headlights on....

test from the negative battery post to the engine block... 0.04 volts is acceptable...

test from the negative battery post to the body................0.02 volts is acceptable..

test from the engine block to the firewall.........................0.02 volts is acceptable..

if you get more than these minimal voltage readings.. you have a problem with the ground.. if you get 0.00.. try turning to a lower DC voltage range...

these tests are critical in diagnosing gremlins.. problems ... things that just don't work as they should...

only takes a few minutes ... can point out invisible problems.. "

(copied and pasted )

 

[john.thompson068]

Wow, I never though my distributor could wear out like that. Mine is pretty new though, probably only 15,000 miles. I could see if it had like 100,000 miles on it so I hope it does not turn out to be the problem. I will be able to test it out with the new ballast either tomorrow or Saturday and will report back.

 

[Sonny Black]

pop hood try to start in "dark" ..look for arc ing.
bad wire, crack dis' cap...etc.
good luck.

 

[74sundance]

Well at least until I get the car running I can look at the awesome progress you have been making with your Sundance. I can't wait to see the rest of your pictures once you have it painted.

Hey Thank's I often wounder if anyone looks at that link haha :upside down:

Keep us posted on your spark issue I'd like to know what the cause is.

 

[john.thompson068]

Well the results for the new ballast resistor are in. First, I checked for spark with the existing MSD 8214 ballast resistor, and there was spark. So when everything is cool there is spark.

Then I replaced the ballast resistor with a brand new one and started up the motor. Everything seemed to fixed until I warmed up to 165* and then it began to run very erratic. I shut it off and checked for spark. It was very weak and erratic, and then there was no spark whatsoever. Later when everything cools off again, I will have spark. I am actually going to run out there real quick and do the ECU test again.

 

[67 B-body]

Well the results for the new ballast resistor are in. First, I checked for spark with the existing MSD 8214 ballast resistor, and there was spark. So when everything is cool there is spark.

Then I replaced the ballast resistor with a brand new one and started up the motor. Everything seemed to fixed until I warmed up to 165* and then it began to run very erratic. I shut it off and checked for spark. It was very weak and erratic, and then there was no spark whatsoever. Later when everything cools off again, I will have spark. I am actually going to run out there real quick and do the ECU test again.

Have you tested the pickup coil yet?

 

[john.thompson068]

Definitely not the chrome box or the FBO coil. This is an unbelievable chain of events. I drive the car into the garage one night. The next morning I go to adjust the timing and discover the FBO ECU has failed. I replace that with a chrome box and now it only runs until it warms up to 165*. My car must like sitting on stands.

 

[john.thompson068]

Originally posted by 67 B-body:
"Have you tested the pickup coil yet?"



No, I'm headed to the pool. Luckily, my step-dad will be in town next week and we can look at the distributor. He is pretty good with stuff like that. I'll let you know what happens.

 

[john.thompson068]

Forget the pool right now. I just tested my distributor and it failed. It read only 365 ohms at the pick up coil and it read only .05 volts from the reluctor. I also read some topics at other websites that point to a faulty pick up coil being the cause of this type of problem and replacing it was the remedy. Looks like tonight I will order P5153576. Now I am going to the pool.

 

[john.thompson068]

Problem solved. It was the pick up coil. Thank you. Now I need the rain to go away so I can hit I75 and show my step dad what she'll do.