24pin vs 28pin DME Upgrade?

[GeneBraddock]

I have 4k/24 Pin circuit board that a bought that has already been upgraded.

Should I upgrade it to 8k/28pin?

Will I see any advantages with the 28pin over the 24pin set up? I get the whole more memory concept but will it help in the performance of the car?

Or should I just keep the 4k/24pin set up and just order a 24pin Chip from SWong for example.

[Raceboy]

There's no performance difference in that.

[Peter M]

Bit more detail here:
https://www.911chips.com/dmeconvr.htm

[ischmitz]

I respectfully disagree with above. The latest stock Bosch/Porsche code that came in the 8k EPROM in the 28-pin sockets is much more advanced and shows better drivability compared to the earlier code versions in the 2K or 4K EPROM. To make matters a bit more complicated there are very different 24pin versions out there. Some have only 1k of usable code/maps and others have 2k or 4k. The lower 4k of stock code comes from the MCU. That is sort of the basic programming and it hasn't changed over the entire production run of the 3.2 DME. All changes happened in the upper 4k segment. And that's where changes were significant:

The first version was only 1k for a additional code and maps in a 24-pin chip. Then came the more popular 2k version in 24-pin chip and finally there is an early 4k version in a 24-pin chip.

The next change was made where the entire 8k of programming was contained in the EPROM and the code in the MCU is no longer used. Only the upper 4k was changed one more time with more maps and different code. All the time ignition and fuel maps evolved further.

Most aftermarket chip tuners (e.g. SV and others) take the stock code of a certain vintage and then modify the maps further. But unless you deal with Sal (he re-wrote portions of the machine code) the base code is left alone and remains whatever the tuner started with. So you need to keep in mind that a performance chip based on old an older 4k EPROM is not the same as a performance chip based on a later 8k EPROM version.

The simple answer is that upgrading makes absolutely sense. It allows you to use the latest stock code with all the improvements Porsche made over the years. Next consider an aftermarket chip with more aggressive timing and fuel tunes depending on what you are after.

Ingo

[Quicksilver]

To simplify what ischmitz said.

- In the 24 pin DME the actual program code is burned into the processor. In other words you have the first programming that Porsche released to run the original 3.2.

- In the 28 pin chip, the DME flips a switch to ignore the code burned into the processor. In the years following 1984 Porsche learned a lot more about controlling the 3.2. The 28 pin upgrade contains their upgraded programming for the DME which is noticeably better.

To be clear: The "programming" of the processor is completely different then the ROM data tables that the DME uses to control the engine. When you buy a chip they are changing the data in the ROM tables. Porsche's upgrade of the programming is a much bigger deal.

[GeneBraddock]

Thank guys, that really helps clarify things a lot. Sounds like I will just upgrade it to 8k since its not that difficult.