I just built and installed a braineak ms3x. Shoutout brain for the diy instructions. Ecu seems to be working fantastic, about to do some idle tuning. I noticed when keying on I get a quick 2-3 second buzz from under the driver side dash. Don't think the car did this before the ecu, thinking it's fuel pump relay priming? Saw a couple threads say a constant is an IAC with incorrect frequency or the IAC is running before the car is. The setting for IAC on key on is off and this is NOT a constant buzz but only a few seconds. Any ideas? Should I be worried or just ignore it. Trying to be extra cautious is all.

 

'94 btw.

 

My fuel pump relay beside the steering column did this when the main 80 amp relay failed open. Could be something else, too.

 

if the relay failed it would have only buzzed once then never again right? I can attach a video shortly.

 

When the main relay failed a relay under the dash buzzed when the ecu tried to engage the fuel pump. It also buzzed if F/P was jumped to GND in the diagnostic box, iirc.

 

I see, you'll have to forgive me if I'm not following. If this is a f/p relay failure why does my car still run? Failing open would mean the relay is never sending power to the f/p? Or would that mean the relay is ALWAYS sending power to the f/p. If so what are the implications of this?

I do have plans to go to a DW hardwire kit for turbo applications, maybe I'll just do it sooner rather than later.

 

Also is the video of the noise, gotta turn your volume up to hear it. I'm beginning to think it's just the fuel pump priming and I was second guessing my work after building the entire ms3x and installing it, not thinking myself capable.

Nevermind the cel, I think it's setup to show CANbus functionality rn? I'll have to look into it.

 

Are you sure it isn't the door buzzer key reminder?

 

Positive, removed that ages ago. Almost positive it's fuel pump. Can hear the fuel rush to fill the lines simultaneously with the buzz. Pardon my overreaction.