Do I need more protection against voltage spikes/noise in car?

Okay, So I have a nano being powered by a l7805 through my car's 12v battery. The nano is receiving analog input from the car's MAP sensor wire and referencing that in order to output a pwm signal to an H-bridge which controls my fuel pump duty. I have a 10k resistor between the MAP and nano to protect the nano when the Map is powered but nano is not(key on engine off).

I've actually been running this setup now for 9 months and haven't had any issues. However, with something like this, it's best to double check and improve where needed. I heard from someone before that I could power the nano from the MAP's Power source in order to make a stable read. However, I'm not in the mood to run a wire under all my interior again right now so any suggestions would be appreciated.

Also, anyone know of a simple way I could record for noise/surges? Measure/record voltage at MAP sensor wire and pwm wire at the same time to check for variances?

Always design your projects with noise suppression in mind.

Hey you are isolating, run the wire to pass the time.

You can use a storage scope to view electric noise.

Or

By some beer and wait till the Nano fails ;).

Any suggestions on how to improve this?

Also Out of curiosity, what if I were to take a battery bank designed for a phone and power the nano through the usb. Would that guarantee no noise even if the car is charging the bank?

Guaranteed ? A battery bank would be a good option.

However, I am not fond of Lithium batteries, fires ???.

Also Out of curiosity, what if I were to take a battery bank designed for a phone and power the nano through the usb. Would that guarantee no noise even if the car is charging the bank?

To answer we need to know what else is being connected to the vehicle. If you are monitoring RPM or temp or _____ those wires need to be protected as well.

Do you have a schematic in mind?

JohnRob:
To answer we need to know what else is being connected to the vehicle. If you are monitoring RPM or temp or _____ those wires need to be protected as well.

Do you have a schematic in mind?

Thanks for your reply.

Sorry, but i'm not quite sure what you mean by this. The arduino is only connected to the map sensor and to the h-bridge. I don't realistically want to use a battery bank if there is a better/easier way.
I am planning on moving my fuel pumps to another location soon and redo/clean up my wiring soon.
If powering the arduino from the 5v power source that the Map sensor uses will really ensure accurate measurements vs. anything else, by "referencing" each other then I don't mind the running another wire.

It seems that I can send my values to my phone through serial monitor via Arduino app. So, technically I should be able to use another Nano to connect to my map signal wire, Nano output pin and of course ground. Power the 2nd Nano with my phone which is an independent/separate power-source. I can convert the output, back to the original input by reversing the map function I used. Serial.print the results side by side, line by line and see exactly how much voltage variance I'm getting between my components.

I already got the code mostly written so as long as my theory is correct I should be able to tell how bad my power source is.

So if I count wires from the nano to your vehicle(?) I get:

12V battery (very noisy)

Ground. Must be single point ground and electrically the same as the MAP sensor.

Input from the MAP sensor

Output to the PWM bridge. You will want to be careful with this output. You can't connect the nano to the same ground as the fuel pump as you already have it connected to the MAP ground. So you need to have some drive circuit that will allow the two grounds to be as much as 1.5V different. Maybe an opto isolator.

Is this close to what you have in mind?

JohnRob:
So if I count wires from the nano to your vehicle(?) I get:

12V battery (very noisy)

Ground. Must be single point ground and electrically the same as the MAP sensor.

Input from the MAP sensor

Output to the PWM bridge. You will want to be careful with this output. You can't connect the nano to the same ground as the fuel pump as you already have it connected to the MAP ground. So you need to have some drive circuit that will allow the two grounds to be as much as 1.5V different. Maybe an opto isolator.

Is this close to what you have in mind?

I'm a bit of a noob so be patient with me here.You got all the connections right, I currently have everything sharing a common ground. I wanted to try to test for voltage spikes/variances as I've been running this setup for 9 months without issue. However, I heard of many people experiencing spikes etc. with the l7805 regulator and I don't want to take any chances as low fuel at the wrong time can lead to a broken engine.
I figured if I use a separate power source for another arduino,I could measure for any potential spikes in the original arduino. I know the devices need to share a common ground to work together, so I figured I could just connect the independent power source ground to car ground. However, based on what you posted, i'm guessing its not that simple.
Map sensor is used by the ecu in a sd(speed density) tune, so it is a very important component and I cannot power the arduino and map independently from the rest of the car. I can however, power the arduino from the same source wire as the map.

It will depend on the car. I have yet to see a MAP sensor that wasn't sharing the vehicle ground. Wise to double check though of course.

AJLElectronics:
It will depend on the car. I have yet to see a MAP sensor that wasn't sharing the vehicle ground. Wise to double check though of course.

Are there any extra steps I can take for added peace of mind. I guess when I think about it, voltage surge isn't really a problem since a voltage increase in the signal wire will just increase the duty of the fuel pumps, but if voltage drop occurs, the fuel pump duty could drop below what is required and damage the engine under wot.
But then again when I think about it harder, if you are giving the car with more throttle the speed of the fuel pump will increase along with the demands, but then the power generated by the alternator would be higher since the engine is spinning faster, might compensate for any potential drop as with will always be working with each other.

Regardless, more safety is always wanted.

I am a little confused (again). Fuel delivery and MAP are not directly proportional. The ECU takes many other parameters into account before deciding on injector timing etc, not the least of which is ambient air temperature and the charge temperature.

AJLElectronics:
I am a little confused (again). Fuel delivery and MAP are not directly proportional. The ECU takes many other parameters into account before deciding on injector timing etc, not the least of which is ambient air temperature and the charge temperature.

It does, my car is supercharged and I had it tuned with a speed density tune which uses manifold pressure from map to configure the tune. So the amount of fuel the injectors supply is dependent on pressure, rpm, temp. Etc. Instead of using a maf sensor. So your right about that.

However, this isn't what I was referring to earlier and I can see why your confused.
To create a more simpler overall picture I'll just explain the purpose.
My car is pretty heavily modified at this point, I use a large external fuel pump to supply fuel, however, running this pump at 100% all the time especially when your just cruising causes the pump to get really hot from recirculating the same fuel over and over. It also gets very loud as it gets hot.
To solve this I used a nano which sends a input to a motor driver that controls the speed of the fuel pump. The nano uses the map as a reference to control the speed. The map pressure changes based on throttle position. So at no throttle, just cruising pump runs at 30% at wot pump runs at 100%.

I would imagine there to be some noise/variance that causes the nano map input to sometimes differ from the nano fuel pump speed outlet. I want to make improvements to reduce possible variances and ideally if realistically possible, have a simple way to measure both these outputs from a device with a seperate power supply so the exact differences between the outputs can be taken into consideration.

The only way possible way I could think of doing this based on my noob brain, is taking another arduino board, powering it through my phone with an arduino app open to read serial monitor. Plug the one analog read pins into each output and of course connect the ground together between circuits because a common ground is always needed between circuits. In theory, since the 2nd board is not suffering from the same voltage variances as map and board, it should measure exact variances between the 2. However, I'm a noob and therefore is is a theory by a noob, so yeah. Looking for opinions and advice.