LS-1 ignition coil emission frequency???

**Whamhammer** · 08-09-2011, 11:50 AM

Does anyone know what frequency/wavelength that the ignition coils on LS-1's emit? I'm pretty sure that the coil packs are what causing the interferrence in my A.M. reception below 900 (a.m.) .

**pajeff02** · 08-09-2011, 02:08 PM

I'll date myself with this reply. We used to install a filter in the power supply to the radio in order to suppress electrical interference. I believe Radio Shack used to carry them -- not sure if they do anymore.

**Whamhammer** · 08-09-2011, 07:05 PM

Originally Posted by pajeff02

I'll date myself with this reply. We used to install a filter in the power supply to the radio in order to suppress electrical interference. I believe Radio Shack used to carry them -- not sure if they do anymore.

I took it to an audio shop, they added a powered antenna amplifier that didn't do anything for me. Then they added a filter between the radio and the harness, it not only didn't help, it stopped my steering wheel radio controlls from working. I had them remove the filter. I just figure that the coils are emitting at a frequency/e.m. wavelength that is interferring with am reception ( I try to listen between 630 and 680). Has anyone encountered this on these cars and overcome it????

**pajeff02** · 08-10-2011, 03:47 AM

I have never switched over to the AM band in our Trans Am the entire time we have owned it. Actually prefer listening to "pipe tunes" when driving it.

**Whamhammer** · 08-10-2011, 07:20 AM

Originally Posted by pajeff02

I have never switched over to the AM band in our Trans Am the entire time we have owned it. Actually prefer listening to "pipe tunes" when driving it.

"Pipe tunes"?? I listen to AM in the car because I like to keep up on current events during my commute. I got bored with most of the music on repeat.

**pajeff02** · 08-10-2011, 06:54 PM

The sound of the engine through the exhaust... pipe tunes.

**Whamhammer** · 08-11-2011, 01:45 PM

Originally Posted by pajeff02

The sound of the engine through the exhaust... pipe tunes.

Ah, that one went over me there, LOL. But seriously, is there anyone I can contact about what wavelength the energy is at? Anyone at G.M. maybe? I had the radio checked ot and its just fine, only when the engines running.I doubt there are any tsb's regarding this, are there?

**BadTA00** · 08-13-2011, 12:15 PM

You can try Ferrite Beads on the head unit power cable and the speaker wires leaving the amp:

http://www.antennex.com/shack/Dec99/beads.htm

**pajeff02** · 08-13-2011, 06:16 PM

Surfing this question on the net I do not find any LS1 specific information. I did find a post in an unrelated forum where automotive coils were tested and the resonance frequency ranged from 2.85 to 3 kHz. No idea if our coils fall within this range or not.

**Whamhammer** · 08-14-2011, 08:51 AM

Originally Posted by BadTA00

You can try Ferrite Beads on the head unit power cable and the speaker wires leaving the amp:

http://www.antennex.com/shack/Dec99/beads.htm

Have you done this before? To get 630 and 680, Id want to use mix 43 or 77?? Also, where do you get these? That websites shop didn seem to carry them.

**BadTA00** · 08-15-2011, 08:37 AM

I've used them to reduce the HF RF for CBs which are AM radios. You'll need mix 31. You'll place them on the power or positive wires only. If you put it on the ground wires they'll have the opposite effect. The alternator and fuel pump could be causing some of you noise also.

Dx Engineering carries Mix 31 in different sizes. You can get them large enough to fit the alternator cable also.

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