still no luck, engine rpm

hi guys

still no luck getting to read engine rpm.

have done so far.

-try to read from tach no luck there 12v signal
-try to read from crack signal not worked
-from injector signal (pulsein) nope...12v, did also try with an opto to get pulses...no work

how can i read from ignition coil by cable wound to it? using a 555?

did also try a hall over the crank sensor, no luck there...

i need to read a clean rpm signal...im quite new to arduino electronics.

did try many links that i got...no results or way to opaque info.

thanks all for reading

on a other post lost along here..there are all the steps is did and did follow guidelines.
thanks

trying to find that post, if i would not be looking for help...i woldnt have posted this

kr

found it, this is the last post
https://forum.arduino.cc/index.php?topic=519139.0

hope this clears up more

kr

thanks

That's a three-page thread.

Why don't you start by summarising in detail what hardware you have exactly, what you tried, what results you got, and why it didn't work.

Having a 12V signal is not a show stopper. Those are easy enough to work with, often even without optocoupler.

i am using a uno on it,

i have try v dividier on tacho signal to reduce to get a good read from it but it kills the needle.
i have also tryed from the crank sensor, couldnt make it work its a 3-5v signal (sqaure) did try to read as pulse with no luck.
took the to the injector, first time y had to program again the uno as it went crazy taking 12v from the injector signal.
i reduced the voltage from injector and had some pulse reading steady till 3/ 3500 rpm after was no use and also runing leaner as those injector are suposed to run saturated and control the pintle for fuel flow volume.
did try to hook there an opto (in series from injector positive in---positive out those first 2 legst of the opto and the other side pin 6 one leg and the other to ground) had no reading and error code on the engines dashboard.

and just as test... wrapped the ignition coil cable and pusle in to try to pick up some signal...reads nothing.
most stuf ii have here are 1k resitors, some mosfets used for the 3d printer (cant remember ref) 555 chips,some lm358p ones, leds, zener,schottky,potentiometers.

once it works i would move from uno to nano .

Danny1000:
i have try v dividier on tacho signal to reduce to get a good read from it but it kills the needle.

What resistors values? What output voltage of your tachometer? What do you mean with "kills the needle"?

i have also tryed from the crank sensor, couldnt make it work its a 3-5v signal (sqaure) did try to read as pulse with no luck.

How was this wired exactly? Did you add a Schmitt trigger to clean up and stabilise the signal? Did you check the waveform on a scope?

took the to the injector, first time y had to program again the uno as it went crazy taking 12v from the injector signal.

You tried to feed a 12V signal direct to the Uno? That'll kill it fast.

i reduced the voltage from injector and had some pulse reading steady till 3/ 3500 rpm after was no use and also runing leaner as those injector are suposed to run saturated and control the pintle for fuel flow volume.

How reduced? What resistor values? What's "running leaner" and "run saturated" mean? What's a "pintle"?

did try to hook there an opto (in series from injector positive in---positive out those first 2 legst of the opto and the other side pin 6 one leg and the other to ground) had no reading and error code on the engines dashboard.

No current limiting resistor on the optical side? How is the complete wiring?

To answer "complete wiring" questions please use schematics (hand drawn is fine), words generally fall short.

Hi Danny1000,

As you mentioned you have tried a lot of methods and nothing works, why not try this:
(Now this is just a theory so try if this make sense)

Vehicles use motors(or dynamos) in speedometer to get the speed of the vehicle.
The principle: Spinning dynamo generates electricity and it's always a function of the speed or RPM of the vehicle.
By measuring this electricity precisely you can get a precise idea of the RPM of your engine.
This method is not only effective but also in use since decades.

If this makes sense give it a shot.
Hope this helps.
:slight_smile:
Best,
Anshu Raj

Anshu_Raj:
The principle: Spinning dynamo generates electricity and it's always a function of the speed or RPM of the vehicle.
By measuring this electricity precisely you can get a precise idea of the RPM of your engine.

That's AC power, sampled before the rectifier, right?
That should work as well. Just use a regular zero crossing detector, and count pulses (two pulses per rotation).

But the other methods OP mentioned are also supposed to work. It's probably just a case of either not understanding what they're doing, or not putting enough effort in it.

hi guys.
its not lack of effort, its lack of know how.
im quite new to arduino so what might looks easy for you its not for me at this stage.

on the other hand been arounf engines for quite a time and its electronics .

regarding the questions.
the pintle is a element in the injector that moves up or down depending how muech fuel flow is needed, saturated is a type of injector type being those the common and the top top one peak and hold type.
difference is the power used to mantain them open and not heat up as much increasing life of them.
running lean means in terms of mixture reducing the fuel part of a given volume of air and so "leaning" out the engine or in this case that cilynder, results in more heat and less performance if its to much and risk of damage.

the engine tells the rpm via a crank sensor or a cam sensor, asked the mech in the shop and he told me its square vaweform.

cam sensor is a hall sensor if i am not wrong, 2 wires.

have not tried the trigger, havent done one yet . (have to make my first one still )
have thought of decoupling if this makes any sense...

i reduced power using a 100k pot, using the same method on the dash rpm cable didnt work at all, it killed the needle ,meaning engine was runing but the needle was pointing at 0.

will draw and upload soon

thanks for reading

Danny1000:
found it, this is the last post
rpm counter FROM tach - Project Guidance - Arduino Forum

hope this clears up more

If you click Report to Moderator and ask to have this Thread merged with your earlier Thread it will make it much easier to help you because all the info will be in one place.

I have no intention of jumping from place to another to get the background.

...R

Danny1000:
cam sensor is a hall sensor if i am not wrong, 2 wires.

This can very well be, and would be a prime candidate to hook up to.

You indeed have to make sure you don't mess up the signal for other systems in your car, such as your normal tachometer.

It is important to know what signal you get out of it. The block wave may be changing in both amplitude and frequency - the frequency is what you want to read, the amplitude not so much. Maybe you can hook up an OpAmp as comparator, one that can handle the highest voltage the signal can produce - if needed using a voltage divider - 10-100k total value would normally be safe.

this is how i have wired the opto to the fuel injector to get some reading.

how would i get a clear signal from the cam sensor to be used with the uno?

thank you

will request merge

opto.jpg

Danny1000:
this is how i have wired the opto to the fuel injector to get some reading.

That misses at least a current limiting resistor in the 12V side. You'll need about 1k for that - check specs of your optocoupler on forward voltage and required current, and size the resistor accordingly. No resistor will kill your optocoupler fast.

Did you enable the internal pull-up of the Arduino? No external pull-up in that sketch on the output side. Won't work without it.

how would i get a clear signal from the cam sensor to be used with the uno?

Probably Schmitt trigger or OpAmp as comparator. Depends on the actual signal.

ok, now i see a new problem using a opto there then.. if the injector does not run on 12v it will a bit more closed (the pintle in it) and that giving a leaner condition to it, if voltage drops due to Vf then this idea can be discarted...levaning only to intercept hall sensor (if no voltage of it is sacrified, as else it would upset real readings for the ecu) or getting a signal direct from the ingnition coil by receiving pulses from wrapping it around (how to do...i dont know)

injector have an operating range from (0) or bit more to saturate the coil to lift the pintle up to 12v meaning 12v is 100% fuel injecting on that unit
i have seen this and attemp to make the same, but for me reading atm the diagram cant make much sense of it (lack of exp)

https://kokoraskostas.blogspot.com.es/2013/12/arduino-inductive-spark-plug-sensor.html

something like just to read the pulses of the igition¿?

how can i read the pulse from the coil?
thanks

finally...found this and could help.

how can i read a square signal with arduino?
thank you

Danny1000:
how can i read the pulse from the coil?
thanks

Not sure if you already described the ignition system (ie age of vehicle :wink: ) but if it's old style distributor and coil, you can get at the LT side of the coil from the distributor (points, or breakerless equivalent thereof) which is what switches the coil primary.

Danny1000:
finally...found this and could help.

how can i read a square signal with arduino?
thank you

Many ways - pretty easy - if you do a quick search on Google you'll have several examples. Depending on the speed you can get away with polling, if too fast you probably need to use an interrupt to not miss pulses.