How stable are people's battery voltage? Mine seems to fluctuate sometimes quite a bit. From about 13.6 I've seen 13.5 up to around 14.2. I noticed yesterday during on the highway I was using veal for the long drive. When I went to use the power windows as soon as I pressed the button my voltage on tunerstudio dropped to 13.6-13.7 I think it even went to 13.5. This was real sudden though but it caused the afr to go lean as well for an instant. Cruising at 15.2 it would flash up to 16.2 or so. I understand that voltage will drop when something demands power but is this behavior normal? It does only last for maybe .25 seconds maybe even shorter. I'm just trying to diagnose any electrical problems as I've seen some odd voltage fluctuations in logs even without me manually demanding power from something.

 

Which alternator do you have, the na type with internal voltage regulation or the nb that has external voltage regulation that can be controlled by ms3? Idk but a 0.25 second delay does not sound bad to me.

 

Sorry I should should have specified i have a mspnp2 and an nb1. Im going to run som test today. What I'm trying to figure out is would me using power windows make the wideband analog signal voltage change? I don't think it should effect the signal but if it does effect my signal then something must be wrong electronically right?

 

If the analog signal voltage was effected with changed in demanding power I would think the voltage would go down like the way the battery voltage does for a quick moment. If that was the case then I would get rich readings. I'm going to hook up a multimeter to the analog signal wire and see hlw the voltage behaves when demanding power.

 

When it seems possessed I always re-check all of my grounds.
Adding grounds will not give you any extra power as many of the intentional grounding kits claim but too many grounds will NOT create a problem.

I once owned a 1979 Fiat X-19.
This might be the very worst car in history regarding weird electrical issues.
During a driveline rebuild I added grounds out the *** to the car.
I grounded EVERYTHING.
My wife drove that X-19 nearly 80k miles without a single electrical failure...

On your car I'd also check the amperage draw for the PW. I'd also check the draw on both the headlights and the blower motor.
I would expect 5+ amps on all of those circuits.
Does it do the same weird **** when you apply another similar sized load?
Is the PW load dramatically higher? You might have a bad motor or gummed up regulators requiring excessive draw.
20-year-old window regulators are prone to be nasty...

The odd fluctuations without reason leads back to poor contacts/poor grounds in my book.

 

Generally I would consider 0.2 seconds to respond to and cancel out a heavy load like a window regulator to be pretty darn good.

This thread caught my eye because I HATED the idea of my wideband going from analogue (sensor) to digital (adc/calculation) to analogue (dac 0-5v linear out) to digital (ms dac). I moved to a Spartan3 wideband controller and am over the moon with this thing. But I still have some voltage fluctuations that I Do Not Like Seeing.



Not to derail but this lead me to buying a DS213 pocket oscilloscope. I took measurements of the 12v supply to the ECU firing various test modes - only one peripheral at a time. EFR boost solenoid, stock NB2 coils, FF640 injectors, idle air valve, VVT solenoid, and both window regulators stalled rolling up. Will post waveforms if anyone is interested.

This isn't likely. The WB should be on it's own ground for reasons exactly like this. And the 0-5V signal that is generated comes after some pretty robust filtering and regulation that is built into the electronics of your WB controller.** Generally. I've only had issues with the scaling of my 0-5V curves when I was using an analogue signal.

 

Thanks for sharing and to the previous comments that others have left thank you as well. True about getting the 0-5v scaling right in tunerstudio. I have spent so much time trying to get the correct scaling but I can't get it to match 100% even in a range of say 11-16afr. No matter what I do the readings eventually will offset what the wideband and TS says. I am not the most educated on electronics and quite honestly wiring of any sort is my least favorite thing to do when adding sensors, gauges, etc. Especially in an nb miata where the ecu is in the best location ever (sarcasm). I'll look into that spartan wideband you mentioned @O R X O N. Now that you mention it I do think the little time it takes to fix the voltage issue isn't that big of a deal. So I was late to respond to this thread because since then I actually switched injectors and now the car and fueling behaves so much better than it had on the previous FIC 1000s. I never found out what the issue was with them but my guess is that I was not told the correct deadtime from FIC. Maybe they were just too big but I was under the impression that with modern injectors that wasn't an issue. But yeah the 1000s were overkill for my goals with the car and I believe the FF640s with a dw200 will be enough for me to max out the stock motor. I cannot express just how much better my tune is now in just a couple days of tweaking tables. I'm no longer leaning out randomly during cruise and my idle afrs are stable and I can even idle pretty lean before the car starts to struggle. Back on track though hey @O R X O N so what is special about that wideband? What did you use before that?