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Old 22nd February 2006, 14:12   #1
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Cool PC to ECU Interface (OBD compliant cars)

Aren't we all fed up of being scared out of our pants when that dreaded "check engine" light comes on in the dash?

Aren't we fed up of being taken for a ride by the auth. service guys with their 1Lakh + devices that tell us to replace the most expensive parts on our MPFI engines?

If only we could talk to the ECU directly, huh?

Well... I dont think we need lots of money to talk to 'em:

I heard that most mordern ECUs have a simple Serial Interface. If this is true, then we should be able to hook it up to one of the COM ports on a PC and use "Hyperterminal" to talk to the ECU !

Making sense of the gibberish it would put out would be the next step. For this we would need to write software that will decode the byte stream; given the protocol.

I'm a computer geek and can do whatever it takes once I have the byte stream on the PC... I'm looking for some help from other computer / electronics / automobile geeks on Team BHP...

Here's what I need at this point:
1. Do all ECUs have a serial interface? If not, electronics guys / gals; let me know what needs to be done to get the data into a Serial / Parallel / USB port on a PC.

2. I would need the protocols to write the software. Is there a "Standard ECU protocol"?

3. 'Erm, not trying to sound dumb, but... where exactly is the ECU located ? - Different cars = Different places I suspect... (I own an MPFI Esteem)

Looking forward to lots of chatter on this thread.

- T u r b o C -
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Old 22nd February 2006, 14:20   #2
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I always thought about this, turbo_C.

If only ECUs were plug n play in our comps, i could change a few parameters.

For eg, if the car is detuned for the indian fuel quality, we can always retune the parameter to accept 97 octane fuel which is freely available in my city.
Makes sense,doesn't it??
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Old 22nd February 2006, 14:24   #3
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Many manufacturers use a non standard interface so after market modders have a tough time. But since we have these ECU remaps, its not working.
Many ECUs are OBD-II / EOBD compliant and you get serial connectors for that.
check http://www.vitalengineering.co.uk/support.htm.
If you search google, you will find many of these connectors with software selling for 100-150$

Actually suzuki, Ford, GM use standards compliant ECU interfaces so its not a problem if somebody is coming in from the USofA that person can get you the hardware.

As for reading the diagnostics etc., its fine, but if you are planning a retune, make sure you are aware of what you are doing else all you will end up with is a blown engine!

Last edited by tsk1979 : 22nd February 2006 at 14:26.
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Old 22nd February 2006, 14:27   #4
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There are handheld scanners out there in the market that retail for as little as 40$. It would make more sense to pick up one of those.
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Old 22nd February 2006, 14:56   #5
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Yeah, Rtech. I was thinking about the scanners.

But, they're priced so heavenly in our country...that too for taiwanese/korean makes. :(
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Old 22nd February 2006, 15:03   #6
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how do those scanners work ?? what eaxctly do they do ??


rev
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Old 22nd February 2006, 16:19   #7
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Quote:
Originally Posted by turbo_c
Aren't we all fed up of being scared out of our pants when that dreaded "check engine" light comes on in the dash?

Aren't we fed up of being taken for a ride by the auth. service guys with their 1Lakh + devices that tell us to replace the most expensive parts on our MPFI engines?

If only we could talk to the ECU directly, huh?

Well... I dont think we need lots of money to talk to 'em:

I heard that most mordern ECUs have a simple Serial Interface. If this is true, then we should be able to hook it up to one of the COM ports on a PC and use "Hyperterminal" to talk to the ECU !

Making sense of the gibberish it would put out would be the next step. For this we would need to write software that will decode the byte stream; given the protocol.

I'm a computer geek and can do whatever it takes once I have the byte stream on the PC... I'm looking for some help from other computer / electronics / automobile geeks on Team BHP...

Here's what I need at this point:
1. Do all ECUs have a serial interface? If not, electronics guys / gals; let me know what needs to be done to get the data into a Serial / Parallel / USB port on a PC.

2. I would need the protocols to write the software. Is there a "Standard ECU protocol"?

3. 'Erm, not trying to sound dumb, but... where exactly is the ECU located ? - Different cars = Different places I suspect... (I own an MPFI Esteem)

Looking forward to lots of chatter on this thread.

- T u r b o C -
Nice idea.

I have heard that something called CAN is used by most of makers. I think you programmers can hack into the ECU memory chips and find out about the complete programs.

Anyway, as far as my knowledge is concerned, I should not disclose anything.

RK
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Old 22nd February 2006, 16:34   #8
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TurboC,
even if you could hook up the ECU to your computer through a Serial or an I2C bus, you wont be able to manupulate anything since every thing stored is in binary format, even if you map all the binary parameters to physical coefficients, is very hard to know what it a particular word is mapped..
an automobile ECU is a combination of a controller + an EEPROM... rechipping means just recoding the eerprom or may be flash memory these days inside the ECU/ ECM. This is not just one chip solution, infact its a module..
Various parameters like fuel maps, idle, throttle position, spark timing, rev limitter, ABS, EBD are all stored in HEX format inside these memory modules. All these parameters are encrypted by manufacturer to prevent hacks and fake insurance claims.
If you read the memory ( EEPROM/flash) what u see is just a series of hex numbers you wont understand which number ( word) is mapped to which parameter to tweak it.. so with out a software map, its highly difficult to play with these numbers...
After market reprogrammed ECUs are not the same as OEM code, software and binaries will be completely developed by the after market company..We can write the code thats easy.. for that i need to know what are the parameters and more imp what controller/ microprocessor is used inside the ECU..
If i am not wrong, rechipping involves changing the entire ECM that includes the controller / processor and the memory unit... what the after market guys do is they use their own controllers/MP, and hardware and develop software for them...
Here is a good link with moredetails:
http://www.europeancarweb.com/tech/0507ec_chip/
hope this helps...
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Old 22nd February 2006, 16:59   #9
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Quote:
Originally Posted by revtech
how do those scanners work ?? what eaxctly do they do ??


rev
Revtech,
these scanners work on OBD-II cars, this is nothing but a software running on your pc or a hand help (palm ) and connects to the on board ECM throug a specific cable, if its OBD-II the interface is a standard serial interface else the interface varies according to the automobile manf..
So running the software on the host, it communicates with the the ECM and on board sensors to provide you with a real time reading of various sensors and logs in the ECM..
Using this you can diagnose if a particular sensor is functioning prop.. for ex if a mass airflow sensor has gone kaput.. you will not get a reading or may get faulty readings.. etc..
this software is not very costly.. it also comes along with an interface cable..
but cost differentiates a quality software with analysis from a cheap software..
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Old 22nd February 2006, 17:02   #10
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Definitely an interesting proposition turbo_c. I just hope it doesnt go the microsoft way and we have to press the Accel+Brake+Clutch to restart If it is reprogrammable, then we can definitely build an interface which talks to it. Need a little bit of reverse engineering. Again that would change with different ECU.

As far as i know,

1. NO. All ECU do not have an interface which is compliant to the "computer" interface. They would use some sort of proprietory ones. Need little googling on this.

2. No standard ECU protocol. This will change with manufacturer of the ECU.

3. No idea.. im still trying to locate the one in my car
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Old 22nd February 2006, 22:12   #11
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do u think it would be possible to remove the revlimiter at the honda garage?? would they do it? or rather would they know how to?? ne clue on this?.. n if it can or has been done how much would it b.. cuz i guess that wud b an easy 5-10bhp increase, eh?

~cheers
-Ash
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Old 23rd February 2006, 00:13   #12
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Oh man I was thinking on the same line as this thread.
Just wish someone would find a way to overcome this obstacle.

I'm still gathering information to help out.
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Old 23rd February 2006, 00:52   #13
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@Buzzinghornets: The revv limiter can be removed easily.
A lot of tuners these can do this. U might wanna contact viper,KS or some good tuner for this.
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Old 23rd February 2006, 04:48   #14
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nitrous : oh i didnt know.. vipers a tuner?? cool.. ne idea what the costs is? n wud that b a 5-10bhp increase??
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Old 23rd February 2006, 07:33   #15
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Quote:
Originally Posted by buzzin_hornets
cuz i guess that wud b an easy 5-10bhp increase, eh?
No it wouldnt be...
The power curve is already on the decline before it reaches your current redline.
Only increasing your redline (and not changing anthing else) would mean your power would just continue to decrease as your engine revved higher.

cya
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