Code 51 - faulty memcal
Thread Starter
Burning Brakes
Joined: Aug 2006
Posts: 1,061
Likes: 99
From: Seattle WA
Code 51 - faulty memcal
Does code 51 mean the prom chip (or the data on it is bad)? I see that code 52 is for the fuel calpack (I'm assuming the rest of the limp-home part of the memcal).
Car was running fine. I pulled my memcal to read the chip (through a moates adapter - I didn't take off the blue cover). It read out fine, but when I reinstalled it, the car ran like crap and threw code 51. I disconnected and reconnected the computer and removed and reinserted the memcal, but still got the 51 and crappy running. I read the chip again and can still read it fine with my programmer. I switched to another memcal (also read out with the same programmer using the same procedure), and it works fine.
Anyone have this same experience? Can the data be stored "weak" on the chip so that a programmer can read it but not the ECM? Can I reprogram the same data without erasing the chip (I don't have an eraser)?
Car was running fine. I pulled my memcal to read the chip (through a moates adapter - I didn't take off the blue cover). It read out fine, but when I reinstalled it, the car ran like crap and threw code 51. I disconnected and reconnected the computer and removed and reinserted the memcal, but still got the 51 and crappy running. I read the chip again and can still read it fine with my programmer. I switched to another memcal (also read out with the same programmer using the same procedure), and it works fine.
Anyone have this same experience? Can the data be stored "weak" on the chip so that a programmer can read it but not the ECM? Can I reprogram the same data without erasing the chip (I don't have an eraser)?
Melting Slicks
Joined: Aug 2003
Posts: 3,399
Likes: 394
From: Lakeville MI
Code 51 is an eprom checksum failure.
I get them from time to time when my eprom moves around in the socket (socketed memcal). I suspect its just a bad connection on one of the memcal/ecm pins. In my case giving it a good push usually fixes it.
I guess its also possible that you have inadvertently written something into the eprom that shouldn't be there.
Try reading it out again and save the file, or you can use the previously read file if you have a virgin copy available.
Make a new copy of the file and then open and save the new copy with an editor program that will update the checksum for you. Don't modify the original copy, since you will use this for the comparison.
Compare both checksums, or just compare the bins with a comparison utility looking for differences.
If you do need to reprogram the eprom, you will need to erase it first with a U/V eraser.
I get them from time to time when my eprom moves around in the socket (socketed memcal). I suspect its just a bad connection on one of the memcal/ecm pins. In my case giving it a good push usually fixes it.
I guess its also possible that you have inadvertently written something into the eprom that shouldn't be there.
Try reading it out again and save the file, or you can use the previously read file if you have a virgin copy available.
Make a new copy of the file and then open and save the new copy with an editor program that will update the checksum for you. Don't modify the original copy, since you will use this for the comparison.
Compare both checksums, or just compare the bins with a comparison utility looking for differences.
If you do need to reprogram the eprom, you will need to erase it first with a U/V eraser.
Last edited by tequilaboy; Apr 14, 2008 at 05:05 PM.
Pro
Joined: May 2002
Posts: 678
Likes: 2
From: Lengede
[QUOTE=tequilaboy;1565015157]Code 51 is an eprom checksum failure.
I get them from time to time when my eprom moves around in the socket (socketed memcal). I suspect its just a bad connection on one of the memcal/ecm pins. In my case giving it a good push usually fixes it.QUOTE]
I had the same problem a couple of days ago when I removed my Romulator and inserted my chip. I pushed the chip with somewhat more pressure against the socket and the code went away.
Arnold
I get them from time to time when my eprom moves around in the socket (socketed memcal). I suspect its just a bad connection on one of the memcal/ecm pins. In my case giving it a good push usually fixes it.QUOTE]
I had the same problem a couple of days ago when I removed my Romulator and inserted my chip. I pushed the chip with somewhat more pressure against the socket and the code went away.Arnold
Thread Starter
Burning Brakes
Joined: Aug 2006
Posts: 1,061
Likes: 99
From: Seattle WA
Thanks for the advice - I'll try wiggling the chip in the memcal to see if it's just a connection problem. Otherwise, I guess I'll have to get an eraser and reprogram it or just burn a new chip.
I did a dos file compare on the bin as I first read it out and now again after the code 51 surfaced, and it says the files are identical.
I was hoping to keep this particular chip alive because it has a handwritten Callaway label on it.
I did a dos file compare on the bin as I first read it out and now again after the code 51 surfaced, and it says the files are identical.
I was hoping to keep this particular chip alive because it has a handwritten Callaway label on it.
Thread Starter
Burning Brakes
Joined: Aug 2006
Posts: 1,061
Likes: 99
From: Seattle WA
OK - check this out. I think my ECU is taking a dump, but ever heard of one going this way?
I tried reseating the memcal, wiggling the eprom in the memcal, etc. No dice. Re-insert a stock abtb memcal; engine runs ok and no codes.
So, figuring the callaway memcal must be bad, I write the program to another eprom and try to run it using a moates memcal adapter. Behaves exactly the same as the original callaway memcal - code 51 and car sputters and stalls. Now, I'm getting pi$$ed. I burn another chip with the checksum bypassed and try it again. Now there's no code and the car starts and runs, but the idle hunts pretty bad and the CEL flickers a little. Finally, just for kicks, I want to make sure I'm burning the chips right and didn't put the adapter in backwards or anything. So, I burn the abtb stock bin and run it through the moates adapter. Runs smooth, steady idle, and no codes. If I make ANY changes to the bin (using tunerpro), I get the code 51, crappy running, etc. It seems like my ECU will only run one particular bin, and not the right one at that!!!
Sorry for the long post - just needed to vent, I guess...
I tried reseating the memcal, wiggling the eprom in the memcal, etc. No dice. Re-insert a stock abtb memcal; engine runs ok and no codes.
So, figuring the callaway memcal must be bad, I write the program to another eprom and try to run it using a moates memcal adapter. Behaves exactly the same as the original callaway memcal - code 51 and car sputters and stalls. Now, I'm getting pi$$ed. I burn another chip with the checksum bypassed and try it again. Now there's no code and the car starts and runs, but the idle hunts pretty bad and the CEL flickers a little. Finally, just for kicks, I want to make sure I'm burning the chips right and didn't put the adapter in backwards or anything. So, I burn the abtb stock bin and run it through the moates adapter. Runs smooth, steady idle, and no codes. If I make ANY changes to the bin (using tunerpro), I get the code 51, crappy running, etc. It seems like my ECU will only run one particular bin, and not the right one at that!!!
Sorry for the long post - just needed to vent, I guess...
Melting Slicks
Joined: Aug 2003
Posts: 3,399
Likes: 394
From: Lakeville MI
Sounds strange. I have to wonder if the original callaway bin file has somehow been corrupted.
I remember that you posted a copy of a callaway stage III bin awhile back. I downloaded it and still have a copy. Is there any chance that is still a "clean" copy. Maybe compare it to the one that is causing trouble in the car to look for differences.
I'm tempted to try it in my car, but I'm out of blank UV eproms at the moment. I also would have to import a lot of calibrations from my current tune to make it run, but it could help highlight a problem with the bin, if I can duplicate your results.
Maybe somebody else is willing to give it a try in the meantime?
Hope you can get it working again.
I remember that you posted a copy of a callaway stage III bin awhile back. I downloaded it and still have a copy. Is there any chance that is still a "clean" copy. Maybe compare it to the one that is causing trouble in the car to look for differences.
I'm tempted to try it in my car, but I'm out of blank UV eproms at the moment. I also would have to import a lot of calibrations from my current tune to make it run, but it could help highlight a problem with the bin, if I can duplicate your results.
Maybe somebody else is willing to give it a try in the meantime?
Hope you can get it working again.
Melting Slicks
Joined: Aug 2003
Posts: 3,399
Likes: 394
From: Lakeville MI
Just for fun, I took your old callaway bin and made a new copy using TunerCat. I then compared the two files in TunerProRT, there should be no differences.
But, the checksum has been somehow updated in the new copy.
Old: 64 08
New: 62 5F
I made another copy with the same result.
I wonder if the callaway had a non-standard checksum.
I tried making another copy of the original with windows. This time the checksums were unchanged. After opening the new copy with TunerCat and saving, the checksum was again changed to 62 5F.
This suggests 1 of three things that I can think of:
Either the original checksum of 64 08 was incorrect
or
The callaway bin had a non-standard checksum calculation that is being interfered with by the editor programs
or
The original checksum of 64 08 was correct for the original bin file, but something else in the file has been inadvertently changed that is resulting in the new updated checksum when the file is saved in the editor.
I'm leaning towards the 3rd possibility, since it seems to fit your description of the behavior.
What is your checksum?
But, the checksum has been somehow updated in the new copy.
Old: 64 08
New: 62 5F
I made another copy with the same result.
I wonder if the callaway had a non-standard checksum.
I tried making another copy of the original with windows. This time the checksums were unchanged. After opening the new copy with TunerCat and saving, the checksum was again changed to 62 5F.
This suggests 1 of three things that I can think of:
Either the original checksum of 64 08 was incorrect
or
The callaway bin had a non-standard checksum calculation that is being interfered with by the editor programs
or
The original checksum of 64 08 was correct for the original bin file, but something else in the file has been inadvertently changed that is resulting in the new updated checksum when the file is saved in the editor.
I'm leaning towards the 3rd possibility, since it seems to fit your description of the behavior.
What is your checksum?
Last edited by tequilaboy; Apr 26, 2008 at 09:14 PM.
Melting Slicks
Joined: Aug 2003
Posts: 3,399
Likes: 394
From: Lakeville MI
I also ran a diff between the callaway bin and a stock 88 4+3 bin.
Most of the differences are predictable like spark advance, idle speed, warm park IAC position etc. but several of the different items are undefined in my xdf file. The file does not look to be heavily corrupted however. The values that I can see look reasonable
The only value that looks strange to me that could adversely affect the idle is:
PID min underspeed error for high p-part and d-part gains.
This is only 100 rpm in the callaway bin compared with 250 rpm in my bin, which could result in somewhat busy IAC control.
Most of the differences are predictable like spark advance, idle speed, warm park IAC position etc. but several of the different items are undefined in my xdf file. The file does not look to be heavily corrupted however. The values that I can see look reasonable
The only value that looks strange to me that could adversely affect the idle is:
PID min underspeed error for high p-part and d-part gains.
This is only 100 rpm in the callaway bin compared with 250 rpm in my bin, which could result in somewhat busy IAC control.
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Melting Slicks
Joined: Aug 2003
Posts: 3,399
Likes: 394
From: Lakeville MI
Just another thought:
I understand that the Callaway has some sort of supplemental fuel controller. I admit I don't have a good grasp of the hardware involved.
Is it possible that this is piggybacked with the ecm/memcal and the checksum is based on both devices rather than that of just the memcal eprom itself.
Hopefully we can figure it out.
I understand that the Callaway has some sort of supplemental fuel controller. I admit I don't have a good grasp of the hardware involved.
Is it possible that this is piggybacked with the ecm/memcal and the checksum is based on both devices rather than that of just the memcal eprom itself.
Hopefully we can figure it out.
Team Owner
Joined: Aug 1999
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St. Jude Donor '10
guys I can tell you from experience..the stock b2k tune was extremely conservative for warranty reasons. If it was my car I'd go to a dyno and custom tune it. You'll pick up a good deal of power and probably better driveability. 
Thread Starter
Burning Brakes
Joined: Aug 2006
Posts: 1,061
Likes: 99
From: Seattle WA
tequila - you hit the nail on the head. I'm an idiot, and sometimes it pays to stop working when you're frustrated because it just leads to mistakes.
Conclusion - the callaway bin is corrupted. I kept assuming it wasn't since I can still read & verify it without error, and it always compares exactly to when I originally read it out. And, I misposted above - I was only working with the callaway bin to get rid of the checksum errors. Too many different versions of things on my desktop...
After a fresh start, I modified the abtb bin, and it works just fine. So, it isn't the ECU.
I know for a fact that the program area of the callaway bin shouldn't be modified, and the aux inj controller does not integrate to the factory ECU in any way. I should be able to restore the corrupt callaway bin by fixing the dropped bits in the program area and double-checking that the checksum tunerpro calculates matches the one stored on the chip (presuming that area of the chip is undamaged). If I can do that, I'll get the posted one replaced with the corrected version.
Thanks for helping me sort this out. To quote my wife "Only you could take a perfectly good Corvette and render it useless!"
Conclusion - the callaway bin is corrupted. I kept assuming it wasn't since I can still read & verify it without error, and it always compares exactly to when I originally read it out. And, I misposted above - I was only working with the callaway bin to get rid of the checksum errors. Too many different versions of things on my desktop...
After a fresh start, I modified the abtb bin, and it works just fine. So, it isn't the ECU.
I know for a fact that the program area of the callaway bin shouldn't be modified, and the aux inj controller does not integrate to the factory ECU in any way. I should be able to restore the corrupt callaway bin by fixing the dropped bits in the program area and double-checking that the checksum tunerpro calculates matches the one stored on the chip (presuming that area of the chip is undamaged). If I can do that, I'll get the posted one replaced with the corrected version.
Thanks for helping me sort this out. To quote my wife "Only you could take a perfectly good Corvette and render it useless!"
Thread Starter
Burning Brakes
Joined: Aug 2006
Posts: 1,061
Likes: 99
From: Seattle WA
new corrected file posted over at moates.net.
I found 5 bits that were corrupted in the program area of the chip. I fixed those, and now the calculated tunerpro checksum matches the one stored on the chip. I tested the corrected bin on the car, and all is good.
I found 5 bits that were corrupted in the program area of the chip. I fixed those, and now the calculated tunerpro checksum matches the one stored on the chip. I tested the corrected bin on the car, and all is good.
Melting Slicks
Joined: Aug 2003
Posts: 3,399
Likes: 394
From: Lakeville MI
Thanks for posting/sharing.
I see that the checksum is now correct again with the corrected bytes in the bin: 64 08
By the way, I'm curious, how did you come up with the correct values for the 5 bytes that were blank? Or, did you just copy them from another bin and then verify that the checksum was correct?
Good job on the corrections.
I see that the checksum is now correct again with the corrected bytes in the bin: 64 08
By the way, I'm curious, how did you come up with the correct values for the 5 bytes that were blank? Or, did you just copy them from another bin and then verify that the checksum was correct?
Good job on the corrections.
Last edited by tequilaboy; Apr 28, 2008 at 09:29 PM.
Thread Starter
Burning Brakes
Joined: Aug 2006
Posts: 1,061
Likes: 99
From: Seattle WA
That's exactly what I did - I did a bin compare with a stock abtb bin that I read off another memcal I had and figured the program areas should be identical. There were 5 bits that weren't. I used the values from the abtb bin for those 5 bits and recalc'd the checksum, which now matched the one stored on the prom.
Intermediate
Joined: Jun 2015
Posts: 30
Likes: 0
From: Nessebar
OK, a VERY old thread here, but can someone help me as to shere this chip is? I've got the 51 error and the car is running erradically rough..
All other codes got cleared and do not return, but the 51 stays on.
I was advised to chech the connections for corrosion etc..
Is this thing inside the cumputer? I have a tech to check and redo the soldering if needed, but I have to bring him the part.
thx
All other codes got cleared and do not return, but the 51 stays on.
I was advised to chech the connections for corrosion etc..
Is this thing inside the cumputer? I have a tech to check and redo the soldering if needed, but I have to bring him the part.
thx
