Alternater
Thread Starter
Race Director
Joined: Sep 2003
Posts: 16,834
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From: Database Error Indiana
Alternater
Heard about this happening to guys over the years, now its happening to me. Remote will not open the garage door with the car running. From threads in the past, consensus was the alternater sending out a frequency of its own or something blocking the signal from the door opener. Is there a fix ? Is my alternater going to die ? If you keep these cars long enough, weird stuff goes wrong. Ive had this one about 13 years. 
Burning Brakes
Joined: Nov 2008
Posts: 995
Likes: 1
From: Naples Campania
I don't think the alternator is throwing a specific frequency, just massive electro-magnetic interference. I've seen this happen on the high power electric motors on my radars, but never even thought of it happening to an alternator. I guess you learn something every day. I would say the alternator is going bad, but I am interested to find out if anyone has actually seen this happen.
Instructor
Joined: Jun 2008
Posts: 173
Likes: 0
From: Norman OK
I guess that would be possible for the alternator to be sending out EMI which would block the signal, but......
Do you have any static on the am bands of your radio? If plug wires are leaking the EMI bleeds thru to the antenna coax.
I guess if you have a portable transistor or house radio, you could set it on an am station, hold it near the alternator and see if it goes nuts....
Do you have any static on the am bands of your radio? If plug wires are leaking the EMI bleeds thru to the antenna coax.
I guess if you have a portable transistor or house radio, you could set it on an am station, hold it near the alternator and see if it goes nuts....
Race Director
Joined: May 2001
Posts: 14,165
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Heh, here's a dumb one for ya. Once upon a time a friend gave me a gear drive system. I managed to install it one tooth out of time. In addition to the car being a total basket case and running like crap, my garage door opener would not work unless I shut the car off.
Eventually I found the timing problem and corrected it. I also opted to go with a double roller chain instead of the gear drive. Magically my car ran better and my garage door would open again. Absolutely nothing electronic changed during this process.
Eventually I found the timing problem and corrected it. I also opted to go with a double roller chain instead of the gear drive. Magically my car ran better and my garage door would open again. Absolutely nothing electronic changed during this process.
Team Owner
Joined: Mar 2001
Posts: 54,124
Likes: 30
From: Cincinnati, Oh USA
I doubt your alternator is the culprit, but most likely its ignition pulses causing the interference with the garage door opener receiver. Garage door opener receivers are pretty crappy receivers (cheap with very poor interference rejection).
Another thing to check is the battery in your door opener, they are probably weak, so replace them. Measure the door opener battery voltage, that will tell you!
Another thing to check is the battery in your door opener, they are probably weak, so replace them. Measure the door opener battery voltage, that will tell you!
Last edited by jfb; Apr 14, 2011 at 12:29 PM.
Thread Starter
Race Director
Joined: Sep 2003
Posts: 16,834
Likes: 337
From: Database Error Indiana
I guess that would be possible for the alternator to be sending out EMI which would block the signal, but......
Do you have any static on the am bands of your radio? If plug wires are leaking the EMI bleeds thru to the antenna coax.
I guess if you have a portable transistor or house radio, you could set it on an am station, hold it near the alternator and see if it goes nuts....
Do you have any static on the am bands of your radio? If plug wires are leaking the EMI bleeds thru to the antenna coax.
I guess if you have a portable transistor or house radio, you could set it on an am station, hold it near the alternator and see if it goes nuts....
Havent used AM in years. May give it a try.
Heh, here's a dumb one for ya. Once upon a time a friend gave me a gear drive system. I managed to install it one tooth out of time. In addition to the car being a total basket case and running like crap, my garage door opener would not work unless I shut the car off.
Eventually I found the timing problem and corrected it. I also opted to go with a double roller chain instead of the gear drive. Magically my car ran better and my garage door would open again. Absolutely nothing electronic changed during this process.
Eventually I found the timing problem and corrected it. I also opted to go with a double roller chain instead of the gear drive. Magically my car ran better and my garage door would open again. Absolutely nothing electronic changed during this process.
I doubt your alternator is the culprit, but most likely its ignition pulses causing the interference with the garage door opener receiver. Garage door opener receivers are pretty crappy receivers (cheap with very poor interference rejection).
Another thing to check is the battery in your door opener, they are probably weak, so replace them. Measure the door opener battery voltage, that will tell you!
Another thing to check is the battery in your door opener, they are probably weak, so replace them. Measure the door opener battery voltage, that will tell you!
Thread Starter
Race Director
Joined: Sep 2003
Posts: 16,834
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From: Database Error Indiana
I'm back. Unplugged the alternater, opener still did not work. Covered the distributer with a piece of metal, BINGO, door works. Now question is, what do I do to fix this problem ? 
Thread Starter
Race Director
Joined: Sep 2003
Posts: 16,834
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From: Database Error Indiana
Fixed. Removed the cap and saw, a screw was missing from the rotor. Rotor was still held firmly in place by the other screw. Pulled the distributor and found the screw and installed an old cap/rotor I had in the garage. All good now. 
Thanks for pointing me in the right direction.
Thanks for pointing me in the right direction.
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Instructor
Joined: Jun 2008
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From: Norman OK
Now, I have to wonder, how many of those who have problems are running without the distrbutor cover that screws on to the rear of the plenium and if that cover was engineered for looks or a EMI shield?
It certainly would act as an EMI shield for the coil, cap, and ign module.
Thread Starter
Race Director
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From: Database Error Indiana
Good Job on the fix..
Now, I have to wonder, how many of those who have problems are running without the distrbutor cover that screws on to the rear of the plenium and if that cover was engineered for looks or a EMI shield?
It certainly would act as an EMI shield for the coil, cap, and ign module.
Now, I have to wonder, how many of those who have problems are running without the distrbutor cover that screws on to the rear of the plenium and if that cover was engineered for looks or a EMI shield?
It certainly would act as an EMI shield for the coil, cap, and ign module.
Good point. I have a Miniram, no way to cover the HEI. I drove a C3 for 14 years. Always had that chrome cover over the distributer. Thing is, the door remote probably saved me from breaking down someplace. The rotor had aparently been pusing up and had the coil contact worn down to nothing.
Thats twice in recent weeks, Ive dodged a bullit with this thing .
Burning Brakes
Joined: Nov 2008
Posts: 995
Likes: 1
From: Naples Campania
I have to admit, this is a very interesting topic. I am currently missing that plate that goes over the distributor. I should probably look into that. This goes into my book of crazy stuff. I guess you learn something new everyday.
You should post pictures of the old distributor so we know what to look at if this happens.
You should post pictures of the old distributor so we know what to look at if this happens.
