Hello all, I've been researching for about a year now and trying what people have done but I'm not getting exactly what I'm trying to achieve. So, in a automotive efi ECU world, There is a manifold pressure sensor that reads 2.33v at idle (on this engine it is 0 to -13kpa) and 3.62v at full throttle full boost of 13psig(88kpa). I would like to trick the ecu to think it's seeing 3.62v while it's actually at 3.9-4v making 16psig(110kpa). Ive made a circuit with a 3.6v zener and resistor (I forgot what ohms, was last year) and I successfully had 16psig without overboost condition. However, the start up and part throttle were rough. When I tested the circuit on the bench I had exactly what i wanted to see with a dual metering scope....2.3-3v moving together until it reached 3.6v after the circuit (to the ecu) and 3.9 before. Didn't work well in real life. Ive seen someone make a fooler with arduino but I couldnt find how it was done or at least a solution that didn't veer off from the idea. I've been trying to self learn coding and principles of circuit components but without asking people that know a lot more than me, I'm stuck lol any input will help, thanks!!
You better look for somebody who can do chiptuning for your ecu. You'd need to turn more knobs than than the maifold presure to get more power from the engine 
I did. One person that does it. I wouldnt get my ecu back until the season is over and for the price I rather trick the map sensor. Also someone sells a map sensor fooler for my application but i cannot justify spending $450 on his arduino and 1.3oled based product. Ive been tuning hondas with hondata and crome for 15yrs, gm on holley, tunerpro rt and tuner studio ms for 8yrs so I would definitely would have my laptop plugged into this thing by now but theres no option under $450 to add an effective amount of power to my jetski. Im in no rush. Ill figure it out one day, any help is appreciated but I wont be convinced to take another path.
Well, if you are 100% sure this will not wrack your engine ... read the voltage with the arduino, add a lowpassfilter to a PWM pin (f ~ 20Hz) and then map the input voltage to the output voltage curve. Most likely you'd want 0-2.6V be linear and 2.6 - 3.9V --> 2.6 - 3.0V ?
Yes well, 0-3v to be linear. This way idle, off throttle and part throttle looks normal to the ecu. I'm sure I'd have to play with voltage amount to perfect it when testing in real life. These are the voltages vs pressures, ignition on engine off. This sensor doesnt see vacuum so anything below 2.3v is irrelevant.
Volts Psi
2.35= 0
2.55= 2
2.87= 5
3.35= 10
3.64 =13
3.69=13.5
3.76=14
3.79=14.5
3.83=15
3.87=15.5
3.92=16
4.02=16.5
4.06=17
4.08=17.5
4.12=18
4.19=18.5
4.24=19
I do not recommend an Arduino for your application. Here is some reading that will explain why.
There is many good app notes such as AN2689 by ST on automotive electronics. reading it will help you a lot.
https://www.st.com/resource/en/application_note/cd00181783-protection-of-automotive-electronics-from-electrical-hazards-guidelines-for-design-and-component-selection-stmicroelectronics.pdf
Also take a look at these: Distilled Automotive Electronics Design | Analog Devices and
Transient Voltage Suppression in Automotive Applications
AEC-100 https://media.monolithicpower.com/mps_cms_document/w/e/Webinar_-_Fundamentals_of_AEC-
Understanding Automotive Electronics, An Engineering Perspective by William B. Ribbens (PDF) .Understanding Automotive Electronics, Seventh Edition An Engineering Perspective by William Ribbens | Roman Perez - Academia.edu
I appreciate your input and informative links you've provided. However, this project has been done with arduino successfully but the information about it is kept secret being the person is selling the potted enclosures with an OLED screen to view pressure. I don't want to copy this persons creation but i want to execute the principal without an OLED screen and be able to make my own adjustments if i want to switch between factory boost setting and +3-4psi. I've measured a current draw of 8Ma so I'm sure pwm with low pass filter would work, as zwieblum mentioned. My issue at this point is I'm not very familiar with coding since I'm still researching and trying to self learn and I cant create my own code just yet. I'm a one on one learner and trying to watch tutorials and reading about it doesn't work too well for me so I would just have to ask how would I compile such code to do my intention and I will end up figuring the rest out.
Try putting a germanium diode in series with the signal.
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