Thread: Electrical load changes AFR's

AEM EUGO wideband. SR20VE. Stock VE inj's, n60. Calum basic ecu. walbro 255lph. b13, alternator less than 3 years old.

While idling if no additional load (ie- headlights, heat, radio) is currently on my idle stays solid at around 14.7. As I turn on additional things like headlights, the AFR will drop to around 12.5:1 and if I turn the heat on at the same time it will idle around 10.2:1. Turn everything off and it goes right back to 14.7 ish.

Recently decided to re-install my stereo (Clarion CZ702, Boss 3k watt max mono, pioneer sub). This obviously draws more power than headlights and affects my AFR's while driving (as the sub hits you can imagine is when it affects it. I will probably throw a capacitor on to see if holding stable supply from power alleviates the draw from the amplifier issues and for good measure will probably throw a few new grounds from engine to chassis for good measure.

Any ideas? Need more information?
Thanks for any help.

I would say to check the voltage at the battery.

Maybe look into where your source of power for the AEM is coming from too.

probably bad grounds.... or maybe a bad wideband controller.

Have you measured the voltage drop at the injectors or battery?

Haven't. Will check for drop at injectors tomorrow. I have an inline voltage meter on the battery so I will monitor that as well when applying load.

Ground, had the same issue and made a ground kit and it was fine after.

Well its definitely not the wideband. Threw another ground on from intake mani to chassis. Now it only goes as low as 11.5:1 but I am thinking its more than just grounds. When I was touching a ground wire to the chassis (which was not connected to anything on the other end) I got shocked. Seemed strange to me but I am not an expert on electrical.

Checked voltage before and after adding load from heat/blower motor and headlights on: Injectors, TPS and battery. Battery stays the same. Injectors and TPS voltages increase. Injectors were going from around .13 at idle to .4-.6 ish. TPS change was there but not as drastic. So it seems like turning on the heat/blower motor switch, headlights or radio system are somehow causing an increase in voltages. Which would explain the richer AFR's if I am correct in thinking that higher injector voltage leads to more fuel.

For the sake of reference I have almost every factory ground still in place on the engine to my knowledge, I have an added 12ga ground from intake mani to chassis and I have a 00ga ground run from the block to the chassis as a replacement for the one that usually comes from the thermostat housing area to the chassis. My battery is in the trunk. The ground from the battery is 0ga I believe.

Today on the way home my fuel gauge needle plummeted at a red light. During acceleration it starting moving back to a normal-ish position. After stopping again it plummeted. I rev the engine in neutral it came back to normal-ish. Starting to think alternator might be putting out insufficient supply to keep the system in its entirety up while running. The only counter to that is I have yet to see the voltage at the battery drop or at the starter for that matter where I have a digital volt gauge wired in.

Not really sure what to think. Since its due anyways I am going to replace my belts and make sure the alternator is nice and tight.

In case my description wasn't enough I decided to record a short video. You can see my stable idle around 14.6. Youll hear my heat come on, afr richens, i turn it off, afr leans. I then turn heat on, then headlights on, then headlights off, and heat off.

MyVideo_zps2601e951.mp4 Video by abihari1614 | Photobucket

Any resolution? I just posted about this same exact issue.
B13, sr20det, z32 MAF, t25, 555's, s4's, Calum realtime
Obviously it's not setup relative swing ours are different....although I am running a uego. Where's yours plummed? I have mine mid-pipe, roughly Mid-chassis.