Electrical Noise at High RPMs

[lazabby]

Is there something in the engine that begins to generate a lot of electrical noise at high RPMs? This appears to be happening to my car and another person's car. The noise seems to be interfering with a device we have. Is there a ground issue somewhere? I notice that my radio in the AM range picks up engine noise.

[dmc6960]

Thats usually the ignition system. Are you running direct coil control on Megasquirt? Did it have this whine before the conversion?

[Bitsyncmaster]

Resistor plugs and resistor wires were used to clean up AM radio noise. Do you both have stock components in your ignition systems?

[lazabby]

Resistor plugs and resistor wires were used to clean up AM radio noise. Do you both have stock components in your ignition systems?

I have resistor plugs and wires. The noise on the radio has always been there even before I replaced wires and plugs a few years ago. That leads me to believe it is something else.

[lazabby]

Thats usually the ignition system. Are you running direct coil control on Megasquirt? Did it have this whine before the conversion?

Yes, Megasquirt is now controlling spark but it seems to be picking up engine noise thus causing some issues.

[Bitsyncmaster]

Here is an idea to try. Take a portable AM radio and move it around the car trying to pinpoint the source of the electrical noise.

[lazabby]

Here is an idea to try. Take a portable AM radio and move it around the car trying to pinpoint the source of the electrical noise.

Thanks. I may try that.

[Elvis]

How did you route the main ignition wire, the one from the coil to the distributor ?

It's not supposed to be routed together with the other wires along that bar at the
fire wall. Just let it hang.

[lazabby]

How did you route the main ignition wire, the one from the coil to the distributor ?

It's not supposed to be routed together with the other wires along that bar at the
fire wall. Just let it hang.

I'll check but I don't think it's tied up with the other wires.

[opethmike]

I got TONS of noise on my Megasquirt when I was getting tach off of coil negative directly from the coil. Those issues were 100% resolved when I moved the pick up to be a splice into the white/slate wire coming out of the idle ECU.

Even though you're running ignition control, I would still suggest moving your connection (output in your case, input in mine) to the inside of the car as described above.

[Spittybug]

Thanks Mike..... Mine is as you describe. Both Shannon and Ian are getting MS resets as a result of sync loss. I suppose it is possible that the MS wire to the coil is somehow acting as an antennae for other noise or something similar.....since the connection is actually an input to MS for the purpose of grounding the coil. It is easy enough to test.

I've learned where to connect the oscilloscope to look at both the VR signal and the resulting ignition pulse. Hopefully that will let us visualize the problem.

[Bitsyncmaster]

The coil neg terminal will see almost a 200 volt spike. That is why you need to keep that wire as far from any other input type wires. You would not want to use shielded wire on the coil wire but your other input signal wires would benefit if you need to run them around other noisy wires.