SR20DET voltage dropping when under electrical load

[jr_ss]

What are the discharge amps of your alternator? Assuming it’s a stock alternator, you should have 90amps at idle.

[Quiche2192]

Originally Posted by jr_ss

What are the discharge amps of your alternator? Assuming it?s a stock alternator, you should have 90amps at idle.

Dunno I gotta measure it. I assume I can't measure it with a regular multi meter but I'll need a multimeter capable of measuring way higher currents than the usual 10A.
Stock alternators, yes.

Originally Posted by slider2828

I've had a similar issue of bad ground at the battery.... maybe take a pic of all the grounds you have? There should be about 5 in the engine bay.

Ok can check that and see. But I did measure resistance and voltage drop between grounds and batt negative and it does look like all grounds are good. BTW I have a Wiring Specialties Pro Harness.

Grounds in the engine bay are:
- One behind each headlight for the chassis harness
- One on the back of the engine head for the engine harness
- One on the intake header for the engine harness
- One for the MAF through the engine harness
- And then I have a dedicated grounding harness that grounds the chassis, alternator body, intake manifold, ground behind the headlights.

One thing I have noticed, I'll hear a whining sound coming from the speakers when the car is running and it kind of gets louder when I turn on the lights.

Right now, I'm thinking about removing that grounding harness to see if that makes a difference. IDK if I'm properly grounding the alternator. There's a bolt that screws into the body and I have a wire going from that to the chassis. I have good continuity between the alternator and the chassis. I don't have a good contact from the alternator body through the bracket to the engine, but that grounding wire should still be fine, right?

[jr_ss]

Originally Posted by Quiche2192

Dunno I gotta measure it. I assume I can't measure it with a regular multi meter but I'll need a multimeter capable of measuring way higher currents than the usual 10A.
Stock alternators, yes.

A clamp on meter can read the amperage.

Originally Posted by Quiche2192

Ok can check that and see. But I did measure resistance and voltage drop between grounds and batt negative and it does look like all grounds are good. BTW I have a Wiring Specialties Pro Harness.

Grounds in the engine bay are:
- One behind each headlight for the chassis harness
- One on the back of the engine head for the engine harness
- One on the intake header for the engine harness
- One for the MAF through the engine harness
- And then I have a dedicated grounding harness that grounds the chassis, alternator body, intake manifold, ground behind the headlights.

One thing I have noticed, I'll hear a whining sound coming from the speakers when the car is running and it kind of gets louder when I turn on the lights.

Right now, I'm thinking about removing that grounding harness to see if that makes a difference. IDK if I'm properly grounding the alternator. There's a bolt that screws into the body and I have a wire going from that to the chassis. I have good continuity between the alternator and the chassis. I don't have a good contact from the alternator body through the bracket to the engine, but that grounding wire should still be fine, right?

If you are relying on just the threads at each ground location, I would advise you to remove the connection, sand the paint until bare metal is visible and add a dab of dielectric grease. Reinstall grounds.