pcmhacking.net

It has come to our attention that there are now Real-Time PCM and ECU conversions being sold online. While we welcome users sourcing their own RT setups we are finding it increasingly difficult to support the unknown hardware being sold elsewhere. While we are happy to help with tuning related queries, all hardware configuration and usage questions must be done with the supplier.

To also help show the differences in what you are getting this is a quick overview and comparison of a NVRAM to suit VS Ecotec and later PCM.


Delcohacking.net / PCMHacking.net PCM NVRAM Genuine Dallas DS1245Y
Industrial temp rating suitable for automotive cabin use
70 or 85ns access speed (the ECU/PCM requires 150ns or faster)
Professionally made PCB using SMD and quality hardware
Power supply filtering
Selectable for VS or VT
Removable jumper to disable writing for when your finished tuning
Easily removable DS1245Y for reprogramming to different vehicles
Support forum containing the developers and active user community.



Genuine PCMHacking products are available in the for sale section here: http://pcmhacking.net/forums/viewforum.php?f=14



Typical eBay RT PCM Cheap counterfeit* DS1245Y
Unknown temperature rating
Unknown access speed rating
Unknown internal (sealed) battery condition
Requires a special adapter for reprogramming (DS1245Y soldered direct to memcal base)
Not jumper selectable for either VS and VT, requires a new unit
Limited support from seller – they direct you to the delcohacking.net forums
Majority of included software and bins developed on delcohacking

* Reply from maxim (who own dallas) on the counterfeit DS1245Y..
“We have no records of manufacturing a product matching the one in your
photo (DS1245Y-100+ 1116L 291972).

We are very aware of counterfeit NVSRAM products being peddled by
brokers, especially via the internet.

We strongly suggest that you purge these units, and see if you can
locate the vendor that sold you those parts; return them for a refund.
(If you wish to help us stop this activity, tell us who it was.)”


Some further notes on counterfeit DS1245Ys
If you are planning on building your own it is becoming increasingly difficult to purchase genuine Dallas DS1245Y NVRAMs. Almost every unit on eBay is counterfeit, the short of it is they are not cheap. Even in larger (10,000+) quantity's you are paying good money per unit. If you want a genuine unit I would suggest buying from a large reputable electronics chain such as Mouser or Digikey.

Of course like all cheap things you get what you pay for. They do not use the same rating and quality of battery as in the genuine article, you will be lucky to get a year or so before it goes flat. This will leave you stranded on the roadside if you dont have a backup memcal. Being a sealed unit the battery is not easily replaceable, so it will loose all the data and become completely unusable. The counterfeits also tend to corrupt very easily.

Because of the use of CR type batteries it could at worst lead to a fire hazard, they dont have a high temperature rating, 60 DegC MAX and that is from a quality brand like panasonic, so the cheap batteries would have much less than this, say 40-50c. Cabin temperatures can easily get this high in a parked car, BR type battery's as used in the Standard genuine ones are rated to 85 DegC. The nvram's for sale on delcohacking are industrial rated, these have a rated working environment of -40 to +85degc with a guaranteed 10yrs minimum use.

Some users on delcohacking pulled appart a counterfeit unit to see what really goes on inside ..
https://pcmhacking.net/forums/viewtopi ... 45y#p18600

Good info there

hopefully will save alot of people wasting money and get the dodgy sellers off ebay!

I've had a few "conversations" with ebay sellers from China and Hong Kong where I've pointed out to them that they're selling counterfeit NVSRAM ICs...
Most denied they were fake to start with - but when I pushed the point, they usually came back with an answer like "We aren't experts and can't guarantee they're the genuine article, but our supplier told us they were" which to me is as close to an admission as you'll ever get
The one in the pic above stands out as a fake, but the case quality is improving to the point where it's getting harder to pick them just from a photo.

Although the fake chips are more or less functionally the same as the real ones, one feature they're missing is the initial battery isolation.
With a genuine DS1245Y the internal battery is not connected to the SRAM until first use, whereas the fake ones start draining the battery during assembly.
That's made worse by the fact that a lot of these fakes are very old - the date stamp on the front is not the manufacturing date (and I suspect old stock is re-screen printed to give the illusion that they're recent production). You could easily be buying a 10 year old chip that was re-labelled last year.

The production code 291972 is a dead giveaway that the chip is fake, and although most of the fakes I've seen have this same code I have seen some where they've used other numbers. 291984 is another one to watch out for...

And to show that even the genuine ones don't last forever, when I went to start my car after a 6 month rebuild the other day, the NVRAM was blank and wouldn't reprogram.
It was a 2003 batch, didn't quite make 10 years - but pretty close

Thanks for the extra info festy I reckon you should send the 2003 DS back to be replaced

I bought a cheap $9 DS1245 chip and it didn't work. Got one from VL400 and all sweet.

so they die after 10 years? I guess its worth burning one to an old fashioned EPROM just in case as a backup.

i typically do in my car anyway, just leave one in the glovebox, have never needed it in the years ive used a nvram but no reason not to.

I'd start to think about replacing them around the 5-6 year mark, but they're probably reliable for a bit longer than that on average.
Whenever they're disconnected from power, the internal power management IC switches the SRAM to a write-protected sleep mode, which draws just a tiny amount of current from the NVRAM's internal battery cell.
It also monitors the internal battery voltage, and when it drops below a certain level it leaves the SRAM write protected when external power comes back - the idea being to prevent possible corruption.
But the write protect mode only comes into play at the lowest possible voltage (to maximize the life of the NVRAM) so the time between being read-only and becoming corrupted isn't that long.
The current the SRAM draws in sleep mode is low enough that the internal battery will usually die of old age before it becomes flat - in which case there is no read-only phase, it goes from working to dead in one step.
The internal batteries are poly-carbonmonofluoride lithium type - which are ultra-reliable and safe compared to the more common manganese dioxide lithium (CR type) - but the trade-off is a lower power storage.
They also hit a "voltage cliff" as they get older, typically they might maintain a voltage above 2.8v for 5 years, but drop below 2v in the 6th year. This depends on load, but Panasonic's lifespan graphs don't go past 7 years even for the smallest load scenarios.
Also, they're lifespan is usually rated by how long they maintain >1v output, but once they get below 2v the NVRAM's power mgmt IC goes into write-protect mode anyway.

12P could be made to test for this condition by reading a memory location on startup, writing a different value to that location and reading it back - if the original value was returned on the second read, the NVRAM is on it's last legs and a DTC could be logged to tell you
(of course this would only work for NVRAM, running from eprom would look like a failing NVRAM with this test...)
But I imagine VL400 has more important things to be working on, so just replace your aging NVRAM chips before they fail

Ideally, using an FRAM/MRAM type of NVRAM would be a better solution - but the >256k versions are all 3.3v so would require buffering, but the bigger problem is that they require a /CS pulse for every read or write, so not a drop-in replacement for the DS1245s

yeah its a problem that isnt that much of a problem. My very original nvram from 2005 is still running to this day, and I havnt seen any genuine ones go flat in my time playing with delcos yet.

12p does actually do a write test to see if its an nvram or rom at startup, so that functionality is allready there, it just doesnt set a DTC. But as said, its worth keeping a backup memcal in the car. And worth not using a fake nvram