They are the worst ecu's out there and alot of vendors sell them since they are authorised!
Mopar electronic ignition ECMs: Which to consider and what to avoid!
- Thread starter Kern Dog
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Greg, this is quite low.
Should be around .50 Ohms.
Did you test with at least one wire disconnected?
Your meter may be inaccurrate as well.
But if these numbers are correct it would explain a number of ECU failures.
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Here are some pictures....
I may have moved the decimal point. I'm seeing a .9 here on the last one.
I have been getting inconsistent readings. Maybe the ends of the probes don't make a good connection inside the wires?
I'm surprised at the wide range of numbers of the resistors I have here. 1.6 ? 2.7 ? I'll get out there to test a few others today.
I do intend to buy the troubleshooting book from Halifax Hops too.
I may have moved the decimal point. I'm seeing a .9 here on the last one.
I have been getting inconsistent readings. Maybe the ends of the probes don't make a good connection inside the wires?
I'm surprised at the wide range of numbers of the resistors I have here. 1.6 ? 2.7 ? I'll get out there to test a few others today.
I do intend to buy the troubleshooting book from Halifax Hops too.
They are all over the place depending on which ECU you are using. Parts store is a crap shoot.
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Those values are all so much lower than these replacements that I've checked here.
Could a high resistance resistor cause failures? I thought the lower resistance ones (lower than recommended) led to increased heat that burned out the coil or ECM.
Could a high resistance resistor cause failures? I thought the lower resistance ones (lower than recommended) led to increased heat that burned out the coil or ECM.
The lower in general creates heat and more amps. Say .25 you do not run on the street, drag is fine cools off between runs. I generally recommend .8 or so for a driver on most. The higher the ohms the less RPMS you will get out of the ecu, Also check them hot lowers the ohm value.
I would expect the resistance to go up with temperature?
Nope no idea why. Try it with say a hair dryer
I would expect that too. The hotter the engine/mix the less voltage needed to get fuel mix ignited. Hence why is a BALLAST resistor.
Yes...
As the ballast resistor's temperature goes up its resistance increases...
Basic idea of the ballast resistor is to protect the ignition coil for over current..
However as I have posted multiple times, some technical issues arise when mixing various ignition components..
The ignition is a system and each component plays a critical part and should be matched...
When mixing various components(brands and origins) certain unknown/reliability issues can/will happen...
Just my $0.02...
As the ballast resistor's temperature goes up its resistance increases...
Basic idea of the ballast resistor is to protect the ignition coil for over current..
However as I have posted multiple times, some technical issues arise when mixing various ignition components..
The ignition is a system and each component plays a critical part and should be matched...
When mixing various components(brands and origins) certain unknown/reliability issues can/will happen...
Just my $0.02...
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Not necessarily.....it depends on what the resistive element component is made from. Some resistors have a POSITIVE COEFFICIENT of resistance (resistance increases with temp increases.) or NEGATIVE COEFFICIENT of resistance (resistance decreased with temp increase). USUALLY the resistor element is made from a Nickel-Chrome alloy (20% nickel-80% chrome) and the diameter of the wire. Different types of alloys results in either positive or negative coefficients. Just thought you might like to know......
BOB RENTON
I always thought Nichrome wire's resistance would increase with temperature. (like every other conductor)
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Incorrect assumption......it depends on the alloy......but there are many different types of resistors that you're probably not aware of.....VDR (Voltage Dependent Resistor..both up and down resistance); Thermistors (Ttemperature dependant resistors ..both up and down resistance). It depends on what the characteristics the designer needs or wants.......remember: all that glitters is not gold......
BOB RENTON
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I didn't know about the difference in resistance for the ballast resistors and how they affected performance. I wrongly assumed that the ECM was solely responsible for the RPM rating of the system.
I tested the resistance in those ballast resistors that are attached to 2 speed wiper motors. Those are in the .8 range. Can they be used for an ignition?
Most likely it can work...
But as I posted previously, each component in the ignition system needs to be matched for reliable, proper operation.. The resistance value of the ballast resistor, should be matched to the coil and has a direct impact on the output voltage of the coil. But then again, what ECM and distributor is used also matters.
Just my $0.02...
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I feel like so much of this seems like common knowledge to some people and a mystery to others.
I freely admit that I've often stumbled through life getting lucky with matters that could have gone one way or another....with me it often goes my way.
I've toyed with these cars for 40 years. The only time I've had troubles with electronic ignitions is with this car: (once)
...This car though....
I can't count the ECMs and ballast resistors I've had in the car.
Every other Mopar was stock and used stock parts that were probably matched for compatibility without me knowing.
The Charger probably has had parts that were mismatched for compatibility without me knowing and it shows.
I freely admit that I've often stumbled through life getting lucky with matters that could have gone one way or another....with me it often goes my way.
I've toyed with these cars for 40 years. The only time I've had troubles with electronic ignitions is with this car: (once)
...This car though....
I can't count the ECMs and ballast resistors I've had in the car.
Every other Mopar was stock and used stock parts that were probably matched for compatibility without me knowing.
The Charger probably has had parts that were mismatched for compatibility without me knowing and it shows.
Jonas Nordstrom
Well-Known Member
I am running the Black Mancini one.
(Which is actually a repainted orange one.)
Its been working good for years now but I still have a bunch of old ones from halifax and a Revnator in storage as I suspect its still a china one inside....
Edit:
Brought the Ohm meter to the car:
Ballast: 1 Ohms
Coil: 0.9 Ohms
(Which is actually a repainted orange one.)
Its been working good for years now but I still have a bunch of old ones from halifax and a Revnator in storage as I suspect its still a china one inside....
Edit:
Brought the Ohm meter to the car:
Ballast: 1 Ohms
Coil: 0.9 Ohms
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With regard to your statement abt the 2 speed wiper motor resistor.....resistors have two values: resistance and watts or power handling ability. Even though the resistance may be close, does the watts rating equal or exceed the power handling capabilities.....can be more but never lessMost likely it can work...
But as I posted previously, each component in the ignition system needs to be matched for reliable, proper operation.. The resistance value of the ballast resistor, should be matched to the coil and has a direct impact on the output voltage of the coil. But then again, what ECM and distributor is used also matters.
Just my $0.02...
BOB RENTON
Look in the fsm it tells you to test them at a certain temperature also. There are a ton of different values out there.
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I've run stock, numbers matching Mopars with NOS parts my whole life, not out of snobbery, but to stay out of trouble. I drove cheap A bodies back in the day, and they all worked reliably. When I moved up to GTXs, also had no problems with stock systems. With a lack of electronic expertise, stock parts and a factory service manual has served me well. I pulled my hair out with electrical trouble shooting with my first tractor trailer in the 1970s, and had no desire to go through the same ordeal with my personal vehicles.
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