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999 Ecn

7K views 28 replies 6 participants last post by  Fastech271c 
#1 ·
Who can reprogram a 999 ECM.
 
#6 ·
This is the MEFI-III system and, unfortunately, has not been cracked by an open source third party supplier. :(

I've been trying to get into this system for years with no luck. In all honesty, it's a very old and outdated ECU that was built on technology from the 1980's. A few guys (Arizonia Speed and Marine, Whipple, etc...) are able to recalibrate the few parameters that are adjustable, but charge a fortune to do it. If you are looking at doing anything more than simple fuel trims, seriously consider a completely new stand alone ECU. It's not as difficult to retrofit as some would have you believe.
 
#10 ·
Ken, yes the Delphi 16236999 is the MEFI 3. I'm working on decoding these and will let you know what my results are in a few weeks. What is your engine serial number, I'm trying to cross reference which models were on each engine. I'd also want to know if they had different programming in these different numbers.

These use a standard protocol and I'm working on cross referencing the numbers to the actual sensors and injectors.
 
#14 · (Edited)
What about the ECM do you want changed?

The four digit code is the checksum and is used for calibration identification - not software compatibility. The code should match what is in the ECM, if not, the ECM has been altered.

That being said, you can have an ECM with the proper checksum, but the wrong or totally different calibration.
 
#15 · (Edited)
partsguy said:
What about the ECM do you want changed?
I am not going to change any parameter until I understand everything in the ECM and test it. What's your experience in programming the MEFI-3 ECM?

I currently have a test bed with a secondary ECM which was reburned by one of the big tuning shops. I intend to compare their program updates to what's in my ECM. I purchased one of the MEFI readers which does match my Checksum on my computer screen to my ECM and what I previously read with the Rinda tool. I am currently interested to know what the programming difference is between Ken's, my modified ECM and my ECM. All were used on 1999 502 engines.

So what do you know?
 
#17 ·
Was their reprogram for an upgraded engine or to a stock engine?

If Ken's is a stock roller cam, cool fuel engine, it will be the same as yours unless changed for some reason and should not take more than a day to turn around unless its being tested on a continually tweaked dyno engine.

What was modified on your non-stock ECM?

My experience is more than just looking over someone's shoulder.
 
#18 ·
partsguy said:
My experience is more than just looking over someone's shoulder.
Thank you for tuning in. I have a question... see below.

The second ECM I have was configured for a Whipple Supercharger and has the Arizona Speed sticker on it. They didn't put a checksum on the side and unfortunately the specifications are not legible. So I really don't know what's in it yet.

My original ECM was for a stock 1999 Mercruiser 502 MPI. When I lookup serial numbers, the same Mercruiser part number comes up for both my engine and Ken's engine. This leads me to guess that the programs must be the same.

Note: I find the terminology "reprogram" to be misleading as from my research these model ECM(s) are configured with new parameters verses actually changing the computers programming inside the ECM.

Are all of the MEFI-3 Programs exactly the same and they differ only by calibration/configuration? Or does each MEFI-3 delphi serial number have diffferent programs as well as a different configuration?
 
#19 ·
ASM may or may not have password protected the modified ECM. If they did, I do not know a way around the security of the ECM.

However, you could get close by putting it on a Whipple engine that it was supposed to be setup for and data logging it as a place to start.

Most ECM's are actually re-mapped - way too many parameters that stay the same to start over every time, not to mention a base program to work from. Depending on the application, some are changed, some are added and some may be deleted. There is a difference between reprogramming and remapping, but the general public views them as one in the same.

All of the MEFI-3 Programs are NOT exactly the same and they differ by calibration/configuration as well.
 
#20 · (Edited)
partsguy said:
All of the MEFI-3 Programs are NOT exactly the same and they differ by calibration/configuration as well.
So is each Delphi part number of the MEFI controllers a different program?

Note: I am aware of the "lock" out to protect MEFI calibrations. Sounds like there is a vendor who's figured out how to bypass the lockout.

Also, did some research and read that the MEFI-3 is quite a good controller and there is NO NEED to upgrade to a MEFI-4... higher numbers don't necessarily mean improved operation.
 
#22 ·
partsguy said:
the Mefi 3 is a very good controller and has proven to be very reliable.
Excellent. Thank you.

Now I read that you can replace an ECM3 module with a ECM4 module (using a jumper wire). I've also noticed a few sites say the ECM3 module is NLA. I talked with Mercury and they have a part number to replace it. I've also noticed some sites call their computer a replacement kit. There is a bunch of mixed information going on here; do you know what the availability of these are and/or can you make better sense of this mis-information?

Have you worked on any of the software to analze these modules and/or prefer any on of the vendors software?
 
#23 ·
partsguy- I am working on command 2 to dump the contents of my ECM. Will I get errors when I try to dump in the memory range of a "locked ECM"? I expect to have the program written either tonight or thursday... hoping to get a dump... Are you working at the command levels? Or are you using someone else's tools?

Also do you know the "Type" number of the MEFI 3 GM ECU?
 
#24 ·
Mefi 3's are NLA and have been for a couple of years, but they are around. It takes considerably more than a jumper wire - that is why its a kit. Same from GM.

I don't know what you will get when you dump and would be interested to find out. I have never used any of the aftermarket software.

I believe there were three or four versions of Mefi 3, but only two that I know of were used in marine and don't see why the other couldn't be as I have used the marine for ramjets.
 
#25 ·
partsguy said:
Mefi 3's are NLA and have been for a couple of years, but they are around. It takes considerably more than a jumper wire - that is why its a kit. Same from GM.
Thanks - so much misinformation out there.

I don't know what you will get when you dump and would be interested to find out. I have never used any of the aftermarket software.
I'll let you know as soon as I complete the program. Partially done last night. I expect all zero's, as many vendors discuss a lockout

I believe there were three or four versions of Mefi 3, but only two that I know of were used in marine and don't see why the other couldn't be as I have used the marine for ramjets.
There is a list by a few of the vendors, though the "type" is what Delphi knows these by on the support line; when I talk to them they only know of the more recent assemblies. The call the MEFI3 old. I think we've concluded that the part number is linked to the program, my guess is that the MEFI3 type is probably all the same Delphi type number.

Who's test equipment have you used? If you want you can send me an email on that. My account here accepts emails now, not PM's.
 
#26 ·
cfm said:
hey Bayley - wass up dude ?

Is this what you are looking for ?

http://www.mefiburn.com/sc/toplevel.asp?cat=32

LS1Nova used it to program his overacheiving 502. Not sure if he has Mefi-II or III.
Yeah, I've read up on MEFIBurn. It sounds like a good solution, but $600 is way too expensive IMHO. At the end of the day, after all the calibrations are made, your final result are simply modified fuel tables with very poor resolution.

The igntion control on the MEFI-I/II/III controllers is very picky and limited in control. The newer coil on plug setup is far superior in just about every aspect.

Fastech271c said:
Note: I find the terminology "reprogram" to be misleading as from my research these model ECM(s) are configured with new parameters verses actually changing the computers programming inside the ECM.
That is correct. The MEFI-X series uses the serial communication bus (J-1850 / Class-2) to initiate a "block write" command into the NVM (EEPROM) section of the controller.

Here is the rub...

In order for the ECU to recognize a valid block write command, the transmitting device must send out two byte of security information. These bytes are commonly called the "seed and key". On every message transmitted from the tester device, the old ket value is ran through a complex algorithm to generate a new key. The receiving module (the MEFI in this case) will compare the new key to the previous one and determine if the message has the correct security setting. Trying to crack these security algorithms is VERY difficult.
 
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