Injector duty?

imloggedin · 06-11-2008, 10:36 AM

I mentioned this in another post but i figured id give it its own thread because its irritating me. Is there anyway to get injector duty from OBD-II? I cant find it anywhere. Im not talking about trim though. If its not in OBD-II can you think of anyway to get it into a laptop? Id like to make an accurate MPG calc from the injector duty/ fuel pressure/ mph.

Thanks

joeyoravec · 06-11-2008, 11:28 AM

Injector Duty isn't available in the government mandated PIDs, but most automakers provide some way to read it over the OBD-II connector. Ford has three PIDs: Fuel Injector Pulse Width (µsec), Fuel Injector Pulsewidth bank 1, and Fuel Injector Pulsewidth bank 2. GM has two PIDs: Fuel Injector Pulse Width Bank 1 (ms) and Fuel Injector Pulse Width Bank 2 (ms). I work on the DashDAQ (www.dashdaq.com) and I know we can read them. They should be available in any tool that can read enhanced data.

imloggedin · 06-11-2008, 11:34 AM

Interesting. How would i go about finding what address they are at so i can tell if i have them?

imloggedin · 06-11-2008, 11:58 AM

What i didnt mention is this is on a 96 Corolla.

imloggedin · 06-11-2008, 05:14 PM

Its amazing how limited information is on this subject. Ive been searching all day for an address of enhanced data for my car. It seems that manufacturers license this data to companies who make scan tools for a hefty amount of money. Alls i need is some addresses, ridiculous.

joeyoravec · 06-11-2008, 07:57 PM

Unfortunately that info is only available (at high cost) to scantool manufacturers; even if you have a ton of money they will not sell to a hobbyist. My only suggestion is to obtain a tool that reads injector pulse width, sniff the communication, and reverse engineer the commands and scaling. I don't think that you will find what you're looking for on the internet.

imloggedin · 06-11-2008, 08:05 PM

ooo good idea

bbalazs · 06-12-2008, 03:37 AM

All things in a car can not be implemented in OBD2 standard. But most car manufacturers have their own program/interface for checking, rading, writing ANY function in THAT car.
eg. I abandon searching for standards, since I found Renault DDT2000, that includes any information my car could have. I made an interface, and wow!
I can even ask for the dimming value of the dasboard, the angle of the steering wheel, the rpm of the internal fan, etc, etc. Of course, it also gives all possible informations about motor functions.

Summarizing: what you need is a car-specific program.

If you are courious exclusively about that info (injector duty), I think you can build a very small electronics (with PIC or so), draining the wire of injector, the info is already available in raw form, the PIC can convert it into ms value and displaying eg. in a small LCD. This is a simple task for a student of electronics.

(in some cars, the injection is not an entire process, but a fast series of injections. I think in this case your value is meaningless or you have to add the separate time segments)

imloggedin · 06-12-2008, 10:02 AM

2 companies have told me that their programs do not have any injector information in enhanced data for my car. i really dont know if its available, i guess i could goto the toyota dealership and ask them to put their diagnostic tool on there and see if its shows duty or pulse width.

ive been thinking about the PIC thing, and that is just beyond me right now. much less the code to calculate pulsewidth and duty. how would u even monitor an input to a pic when the ecu uses a ground to trigger the injector on. you would also need MPH and fuel pressure in the same PIC. MEH.

why cant this be easier.

joeyoravec · 06-12-2008, 11:13 AM

What kind of toyota vehicle? It's not listed in your forum profile.

imloggedin · 06-12-2008, 11:17 AM

Its a 96 Corolla. Can you tell me if that information is even available on my car over OBD?

bbalazs · 06-12-2008, 05:02 PM

Quote: Originally Posted by imloggedin

ive been thinking about the PIC thing, and that is just beyond me right now. much less the code to calculate pulsewidth and duty. how would u even monitor an input to a pic when the ecu uses a ground to trigger the injector on. you would also need MPH and fuel pressure in the same PIC. MEH.

Pulse is pulse, regardless the polarity. You have to detect the edge - rising or falling - it depends. And the opposite transition gives the end of the pulse. Not difficult at all.

The fuel pressure is usually the same (the absolut value could vary car to car), there is a regulator that tries to keep it as constant as possible. Otherwise, I do not think that the time-constant of the pressure sensor makes it possible to operate with exact, real-time values. I think it is not a big mistake if you calculate with the average fuel pressure.

imloggedin · 06-12-2008, 05:05 PM

Possibly not a big mistake, but if you do calculation you can see that it will make the mpg fluctuate quite a bit if you dont take it into consideration.

bbalazs · 06-12-2008, 05:34 PM

I do not know, but do not think that the mechanical response time of the pressure sensor is quick enough to measure eg. the immediate drop after opening of the valve. This pressure drop depends the duration of the valve opening, but it also influences the amount of the fuel injected , and so on...

imloggedin · 06-12-2008, 05:40 PM

Im not gonna argue about it, I just wanna get pulse width over OBD-II.