MSefi.com read only forum (Jan.15,2018)

hello can anyone help me my situation is like this i am doing my megasquirt v2.2 board and i using stim v2.1 version. i finish solder all the Input Section Construction and i plug in the stim power it up and check on the computer all the gauge got respone when i turn the stim knob but the rpm just can only reach 700rpm it wont go up and i play with it few min than suddenly all the gauge jump up and down going crazy and can hear a beep sound come out of my computer and it keep on reseting itself . i did off it and on the power supply again all the thing back to normal after a few min and it go crazy again. did u guys have this kind of situation before can u guys guide me to solve the problem please.......because i completely stuck!!!!!!!!!!!!!!.

Did you verify that you are getting 5V between the pins 1,2,19,20,31,32 like discussed in the manual after you assemble the power supply? What power are you using for the stim? Wall connector or 9V battery? How about the communication section? Did that go ok? Verify that the wall connector (if you have one) is getting you 12V - you can take a volt meter and with the wall connector in the wall take the cord (not hooked up to anything) and take the neg lead to the outside of the connector and send the pos. right through the middle - you should read 12V. What voltage are you getting across C15? You should see 12 - you should rule all that silly stuff out first - does anything work - coolant, o2, etc? I would go through every component you soldered and make sure you don't have a short anywhere - set the voltmeter to resistance and check any two adjacent solder joints - they should all read "OF" or very high resistance like in the Mega ohms or kilo-ohms. If you read 0.001 or 0.002 ohms you have a short - If section 1 is ok (you have 5 volts everywhere you are supposed to), Sect 2 is ok (you can communicate w/ the ms) then check all of the steps in the input section - is the clock working ok? If the major components are ok (5V, clock working, communicating) it should be something simple in your last few steps. Have you been cleaning the excess flux or have gotten anything wet? This could lead to a short somewhere.

Hope this helps.

ok i have check everything.
1. the supply for pins 1,2,19,20,31,32 have 5 volt and all have good ground.
2.C15 have 10 volt supply cos my wall connector switch to 10 volt
so i plug all the thing back and check on the computer it still the same so i think maybe is the ignition side cause the reseting of the processor. so i unplug 555 timer and test agin all the thing when fine just the rpm and IAT is not working so i check the resistor for R4 and R7 the resistance value is okand is in the value but when i check voltage R4 and R7 both have 5 volt coming in but when going out of the resistor R4 i get just only 0.70volt and for R7 is 3.70volt. so what cause R4 just giving out 0.70 volt ??? and why i unplug 555 timer the system become normal and will not cause reseting??? please help me cos i being checking for the board for 2 days already but still cant find any fault area and all the joint is ok no short. so please help me

The voltage being pulled down is, well, how the temperature measurement circuit works. It's a voltage divider with R4 or R7 being one leg and the sensor or trim pot being the other.

It sounds like the LM555 circuit may have been shorted out and causing the MS to briefly lose power. Not something you see very often.

thanks for everyone helping me i found the problem already. first it cos by my stim cos the 10k pot got low resistance so made my gauge going high and also cause by excessive flux making shorts and my rpm is not working is cause by the transistor puting the wrong position hehehe careless me hehehe . now i am soldering the input section hope nothing goes wrong again. hehehe thanks all of u