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Communicating on J1939
RiverRatt
#1 Posted : Monday, November 23, 2009 12:29:24 PM(UTC)
RiverRatt

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I don't know if any one of you is a electrical engineer... I this is not a boating project.

I would like to build a device to talk on the J1939 communication line.
The device will mimic the EGR (exhaust gas recycle) mass flow module on a Mack Truck.
Which will shut down the EGR and increase the fuel mileage
The EGR module is a standalone module, with only 4 wires. +-12V and the two 1939 communication lines.

1 - I need to figure out and understand what the engine computer is asking for? (I do have a service program that can read the 1939 raw data)
2 - Build a device out of some type of microcontroller.
3- Be able to program the microcontroller.

I have some basic electronic skills, but I have only read about microcontroller chips.

To any electrical engineers.
Can this be done by someone with basic electronic skills with a reasonable amount of effort?
Any suggestions? for example- don't waste your time and get more sleep.
"The is no dumb-ass vaccine" - Jimmy Buffet
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dougrose
#2 Posted : Tuesday, November 24, 2009 2:33:51 PM(UTC)
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Sounds kind of illegal. Still, EGR is as thermodynamically as stupid as leaving the reefer door open. I guess the issue might be to know what else needs to be altered to take advantage of shutting off the EGR. At this point, I am out of my depth, some real engine guy (fastjeff?) might be able to help.


1975 32' Flybridge Sedan, twin Perkins 6-354 diesels, 1:1.53 velvetdrives, 16 X 19 props. Merritt Island, Florida
fastjeff
#3 Posted : Tuesday, November 24, 2009 10:44:36 PM(UTC)
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dougrose
#4 Posted : Tuesday, November 24, 2009 11:42:45 PM(UTC)
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I have two diesels in the boat, and one each in a car and a truck, but they are older all-mechanical engines.

So, I am only a little bit familiar with the J1939 specification, that defines the data being transmitted by Parameter Group Number (PGN) and SPN. I assume there is an SPN value sent by the EGR module that means "Yup, we're kicking the s--t out of your efficiency". The computer checks for a value for that SPN in the range of allowed values.

The easiest way to do this would be to get a test module that sends a value back on the bus. This might be a tad expensive. Another way would be to figure out the transducer that is connected to the EGR module (I have no idea what it is measuring) and replace it with a resistor.

You shouldn't do this, but you can make up for it by spending a little extra time each day with your arms around a tree....


1975 32' Flybridge Sedan, twin Perkins 6-354 diesels, 1:1.53 velvetdrives, 16 X 19 props. Merritt Island, Florida
marinettejoe
#5 Posted : Wednesday, November 25, 2009 2:27:07 AM(UTC)
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Yes, it can be done. And CANBUS, NMEA2000 and J1939 is a boating project. Boats have engines.

So Despair not, today there are really cool kits (even ones that can add EFI and J1939 to a Chrysler L engine (318, 360) or big block that NEVER HAD J1939).

If you don't want to design your own, buy a pro-tuner kit. You might consider a Diesel performance bolt on (chip) kit for engine controllers. http://www.comfleet.com/...s/Pittsburgh_Power.html et al. You need to know what type of diesel the tuning kit can use. One of many http://store.edelbrock.c...rformancesystems-2.aspx Get a diesel protuner magazine. See http://www.tuningbox.com/ (ad inifinitem). And more ... http://www.idc-solutions...7DieselPerformance.html Spend the time to research this and ask around. Don't do whatever the first shop says, get a second opinion. Read up on it.

Finally there is the switch and resistor trick accross the EGR sensors. Fools the ECM. But as Doug said you should not do this.

BigM There are so many options it's unbelievable.

You generally program all of these these with a laptop or a hand held.

-------------------------------------------- or Build it your self -----------------------------------

To understand CANBUS, you'd want to get the set of J1939 SAE message docs from the SAE site. About $599. Don't buy it unless you have to. Go a friends shop and borrow it.

Getting the Electronics Lab together is not cheap, but it's worth it. Once you have the skills, you can kick A** over the NMEA 2000 installers and other guys.

Stage the learning....
First. since you've never used a microcontroller, get some skills (Order servo and Nuts and Volts Magazine, and buy a simple microcontroller kit). Build something with it. Easiest is the Parallax Basic Stamp (Radio Shack). This gets you some basic skills. A better choice is an e-blocks kit. You need an CANBUS reader for the PC (KVASER Leaf Light).

http://microcontrollersh...fo.php?products_id=2363
Second - DO A Listener Project : Other than the Basic Stamp which is a throwaway project that takes a day, you need to pick a good CANBUS learning evaluation board. (LIke the Luminary 8962). If you cannot program C, use a Flowcode development kit. like http://www.cancapture.co...ure/functionblocks.html etc. You are going to build a listener project. You might be $800 into the project Mikroe makes some good options.

Third, since this is a talker you need to select and develop the talker and the tuning curve for the EGR. You have to understand how how will it respond to the sensor messages? Also you can "s*rew things up" with a talker that sends incorrect messages while you are debugging. I would be comfortable with debugging that, but would guess few others are.

I therefore suggest a pro-tuner kit (or going to a protuner shop). Ask them what makes sense for your needs.

Anyway. I would build it if I had the time. But I am an MS in Comp Sci, and an engineer.
BigM
Unzinced ships sink at slips. yep
marinettejoe
#6 Posted : Wednesday, November 25, 2009 3:01:43 AM(UTC)
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Also see http://www.tunerpro.net/ for some free software. Don't know much about it.
Unzinced ships sink at slips. yep
marinettejoe
#7 Posted : Thursday, November 26, 2009 3:36:37 AM(UTC)
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To those who want to develop their own stuff... and start a company...

The smarter companies that do this stuff (though I got a negative from NMEA on the NMEA 2000 modeling or use of formal) use formal methods in developing the software stack. I would use these if:
1) I am sending on the engine bus (generally not recommended for most amateurs).
2) Using this to fly a plane (DO178B)

Here is a link to a sciam article on formal methods.
http://www.cs.virginia.e..._Software_by_Design.pdf

Worth a read.

Unzinced ships sink at slips. yep
RiverRatt
#8 Posted : Friday, November 27, 2009 4:47:51 AM(UTC)
RiverRatt

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Great information, Thank you...

I have some studying to do.

I am going to try a software form a company that I have bought USB adaptors from.

http://www.dgtech.com/product/dlm/dlm.php

I will fill you in on how it works.
"The is no dumb-ass vaccine" - Jimmy Buffet
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