1G/2G ECU RPM wire signal value

[teknicalissue]

Hey guys,

For those of you that don't know; I'm working on a functioning electric supercharger called an e-charger. This isn't your average ebay POS that is powered by a pc fan. The page is here if you want to read more about it:

http://www.dsmtuners.com/threads/no...er-supercharger.489506/page-10#post-153510534

That being said; In order to make this work and make this application tunable, I'm going to need to tap in to the RPM wire attached to the ECU. My question is; What kind of signal does the ecu green wire put out? I've read online and some say it pulsates and others say its 0 ~ 12v. I would love for someone to go in there and check this for me as I am developing software for the e-charger that will allow you to allocate certain amounts of PSI per RPM (up to 4k).

for my 1G guys; I'm going this route for you guys as I could have easily connected Arduino to an OBD2 plug

As a side question; does this signal differ from car to car? or is there a standard? I'm planning to build a DSM kit and a Subbie kit once I get the prototype tested.

Thanks!

 

[brads]

It is fairly common to have a single pulse on the tach line for each spark plug firing. So on a 4 cylinder car it is 2 pulses per engine rev, 4 pulses per engine rev on an V8, and 3 per rev on a V6. Some will be 0 to 12V square wave(very common) while some will be 0-5V. If you are designing hardware to handle this all you need to do is set it up to trigger in the sub 5V range and monitor frequency, but have protection on the line to protect against pulses of up to 400+V(in case someone wires it to a coil -ve instead of the regular tach line).

 

[teknicalissue]

It is fairly common to have a single pulse on the tach line for each spark plug firing. So on a 4 cylinder car it is 2 pulses per engine rev, 4 pulses per engine rev on an V8, and 3 per rev on a V6. Some will be 0 to 12V square wave(very common) while some will be 0-5V. If you are designing hardware to handle this all you need to do is set it up to trigger in the sub 5V range and monitor frequency, but have protection on the line to protect against pulses of up to 400+V(in case someone wires it to a coil -ve instead of the regular tach line).

Thanks for the response! I'm hoping the 1G's are 5v so I can directly attach the RPM ECU wire to the arduino module.

 

[o0GuitarKid0o]

Hmm I know that the rpm signal is alternating current (ac) so you might need to convert that signal into DC current if your arduino won't read that ac signal

 

[TSiAWD666]

I don't think you understand what DC and AC are, and it's a 5V square pulse triggering two times per revolution as Brads described.

 

[o0GuitarKid0o]

Just going off how I measured it so I'm assuming he wanted to read it properly in ac voltage cause that's the signal the ecu has correct me of I'm wrong wouldn't he still need to convert that signal to read it properly? Plz explain I'm all about learning new things only ever new that DC is direct current ac is alternating current measured in hz (wave forum) right orrr was I slacking in school ?

I'm more of a schematic kind of guy haha new to this fabrication kind of stuff with arduinos in particular

 

[teknicalissue]

Just going off how I measured it so I'm assuming he wanted to read it properly in ac voltage cause that's the signal the ecu has correct me of I'm wrong wouldn't he still need to convert that signal to read it properly? Plz explain I'm all about learning new things only ever new that DC is direct current ac is alternating current measured in hz (wave forum) right orrr was I slacking in school ?

I'm more of a schematic kind of guy haha new to this fabrication kind of stuff with arduinos in particular

I have very limited knowledge so anyone else please correct me if I'm wrong in attempting to explain this.

Essentially AC signals are a sin wave. Meaning they look like this a majority of the time:

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The wave can represent any given voltage between a minimum and maximum amount. So in other words if you have a 5V signal, AC can provide a frequency of 0v,1v,2v,3v,4v,5v which produces a wave like frequency also known as a sin wave.

DC signals are unidirectional and are either there or not. With DC you either have 5V or you have 0 which produces a square wave:

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A square wave is usually a digital signal as 5V can equal 1 and 0v can equal 0. Unlike AC, A digital signal can't contain a range of 1v,2v,3v,4v between a 0v and 5v signal. It's either there or not. This produces a square wave of on's and off's. When the signal is there it stays there for X time and when it's gone it's gone for X time.

Granted, all of this can change with the help of additional hardware where you can convert DC signals to analog and vice versa. This is just a very extremely simple run down

Again, I am not a professional and this is based on only a couple of days worth of reading information on the net. I welcome anyone that wants to correct me with open arms as I too want to learn just like o0GuitarKid0o.

I don't think you understand what DC and AC are, and it's a 5V square pulse triggering two times per revolution as Brads described.

Perfect! am I correct in assuming this is the same for 2G's as well? I should be able to make that 5V square wave work with the arduino! Thanks for the help guys!