DME upgrade

luyckxglen · 07-19-2012, 06:38 AM

Hi did any of you guys try this upgrade?

Sometime in 1987, Porsche upgraded the software used in the U.S. 84-86 911 Carreras, from a 2K to a 4K program. The primary differences were refinements for an improved idle and additional part throttle performance and response. All 84-86 911s can upgrade to the later 4K program by a simple jumper move and readjustment of the base idle speed. If your 911 is an '84, '85, or '86 model, there is a 50% chance your computer may be a 2K DME, in which case you will need to unsolder and move a single jumper to update it to a 4K DME. After you make this mod you can still run your old chip without changing the jumper back.

Your computer is a 2K unit if it looks exactly like figure 1. If it does not look exactly like figure 1, you already have a 4K unit, and do not need to do anything further. Figure 3 shows examples of computers that are already 4K DMEs that do not need any modification.

Converting a 2K 84-86 DME to use the later 4K chip:

Just unsolder (or clip off) the jumper that connects "B702" and "B1" and solder it (or a new one) between "B703" and "B704"

Note: this conversion will do absolutely nothing for the ROW/European spec 911s and only applies to North American and Japanese cars that come with a oxygen sensor and catalytic converter from the factory.
911Chips.com - Motronic DME Update

Let me know if its worth trying

Tippy · 07-19-2012, 07:29 AM

Pffft.....4K?

They had 8K too.

My '87 had an 8K conversion to the DME to run a custom turbo chip.

BTW, I took a 2K to 8K. They all can be modified from understanding.

luyckxglen · 07-20-2012, 11:54 PM

and is it worth upgrading to 4 k then? cause it seems easy to do?

Quicksilver · 08:00 AM

The actual program code for the 24 pin DME's program was stored in ROM on the processor itself. The ROM chip simply held the maps for the desired ignition and fuel delivery. Having to work with a fixed program kind of ties your hands.

Then the DME was updated to 28 pin in the later part of 87. What this did is allow the program to be changed. The original program is still there but one of the jumpers is simply telling the processor to go to the external ROM for its program.
That is why the chip is bigger: To hold the actual program and also hold the fuel and ignition maps. This allowed them to make any program changes that they wanted and apply what they had learned from all the cars they had shipped.

When I had my DME repaired a couple years ago the one big change I made was having it updated to 28 pin. I put in the 1267355358 chip which is the last chip the factory made for the 3.2. It is identical to the 1267355330 Club Sport chip except for the redline. (6550 vs 6850 if I remember correctly) Seeing that the 3.2 has an internal rev limiter built in (ie: sketchy stretch-to-torque rod bolts that go boom when you over rev) I think the 1267355358 is much more to my wallet's taste.

End result:
The 28 pin update allows you to have the factory's latest programming as opposed to just the latest map. This gives you smoother idle, response and more power. All good stuff.

KFC911 · 07-21-2012, 08:17 AM

Quote:

Originally Posted by Quicksilver

The actual program code for the 24 pin DME's program was stored in ROM on the processor itself. The ROM chip simply held the maps for the desired ignition and fuel delivery. Having to work with a fixed program kind of ties your hands.

....

^^^ This! Moving from a 2K to a 4K chip doesn't mean squat for a typical owner...it's the "subtle map changes" that net the differences in performance between the versions. Takes me back a few years (fresh out of college) when DMEs appeared and I was developing microcode for IBM.... PROM(s) & EPROM(s)...good stuff

jplucas · 07-21-2012, 08:32 AM

My car is hugely different with 4k conversion & SW chip. Better at every RPM point.

KFC911 · 07-21-2012, 09:09 AM

Quote:

Originally Posted by jplucas

My car is hugely different with 4k conversion & SW chip. Better at every RPM point.

Go back and reread Quicksilver's post. I've had one of Steve's chips for years, but make no mistake, place Steve's "maps" on a 2K chip, and the results will be identical to the same "maps" on a 4K version (or 8K, or 64 GIG version

). The larger capacity simply facilitates "upgrades" and some allow for multiple versions of the "maps" (all good).

jplucas · 07-21-2012, 05:41 PM

Steve sent me a 4k chip so I have no SW+2k to compare to, just stock+2k.

luyckxglen · 07-22-2012, 01:20 AM

tell me more about this steve wong chip

how do i install it where do i get it?
Cause ive read alot about it.. Now my trottle responds is so slow.. is it normal? And ive heard you can easly upgrade the US 3.2 to european model?

KFC911 · 07-22-2012, 03:25 AM

Quote:

Originally Posted by luyckxglen

tell me more about this steve wong chip

how do i install it where do i get it....

"Chips suck, case closed" - an infamous quote by one of Steve's incognito marketing agents

. It's all in the search archives...nearly a decades worth of information and "debate". The OP has a link in his first post...

luyckxglen · 07-22-2012, 04:45 AM

i am the op

But okay i think ive got the main info.. only price is a lil high for a chip? 375 $ not incl shipping..

KFC911 · 07-22-2012, 05:15 AM

Quote:

Originally Posted by luyckxglen

i am the op

But okay i think ive got the main info.. only price is a lil high for a chip? 375 $ not incl shipping..

Oops...I wasn't paying attention

. I'm not one who will claim it's an earth shattering upgrade, but I've had mine for years and it's a nice improvement. BTW, we have 93 octane here (so the timing is "safely" tweaked a bit more over the '88 stock version). If you by chance have an '84-86 MY, then you will absolutely "gain" 10 more hp than I did (Porsche changed the maps in '87). Although the price has increased since my purchase, as I recall, Steve offers a "satisfaction/money back guarantee". The man knows his stuff and offers great advice & support imo. Good luck!