Mark944na86

I've discovered that S2 changed the Bosch DME midway through 1990:

Bosch DME Unit
Porsche 944S2 1988 - 1990 0 261 200 195
Porsche 944S2 1990 - 1992 0 261 200 458

OK, so what happens if you put a chip designed for the later unit into the earlier one? The reason I'm asking is that I was considering buying a Weltmeister chip, but it is unclear whether it was designed for the early of late DME unit. It's advertised as a 90-92 chip, which would indicate it was designed for the later DME, but the Weltmeister site only indicates Weltmeister only seems to make one S2 chip, and it is for the 89-90 (i.e. earlier) DME!

ProMax Motorsport http://www.promaxmotorsport.com/ at the very least make two separate chips for these different DME units; it's not clear that other manufacturers do.

Anyone know what the story regarding differences/interchangability is? Obviously don't want to buy a Weltmeister chip that won't work, or will cause damage.

Mine is the earlier DME, BTW.

-Mark

Mark944na86

No-one?

Not enough S2s out there, obviously. If this were a question about about an '86 951, I'd have at least four replies already, and at least five arguments on my hands!

Oh, the loneliness of the RHD S2 driver.

Hey, I even discovered something else "interesting" about later model DMEs. Apparently, to keep parts inventory under control, they had fours sets of AFM maps encoded in the one EPROM, selectable by a switch. The four maps corresponded to:

1) California
2) Rest of US
3) ROW

and the last one is...

4) Australia

Now that's even more encouraging!

So... any RHD-S2-DME-set-to-Australian-AFM-maps experts out there?

:sob:

-Mark

Eric in Chicago

Sorry I cant help you Mark, but I do know that the other options (ROW) can be enabled to gain more HP. Not sure how that would effect a street car but many racers do pick up HP by running the ROW map. I have run chips in my 993 and 944 S2, never saw a great increase in HP but did seem to smooth out the power delv. I think it was a placebo effect. As for changing your map, a good race shop should be able to help you out, doubt you will get much info on ROW maps here. Race shops/racers dont generaly share that info on public fourms

Peter Badore

Here is what Porsche said in the 1991 model year 944S2 Service Information Technik (sic)
"From the year 1991 injection valves with brass coils are being used. The injector valves of the Model 91 are smaller and are colored coded brown at the plug connector. The magnetic coils have a resistance of 16 ohms. Due to the higher specific coil resistence of the new injection valves the ballast resistors in the engine compartment are being deleted. The injection valves used until the end of the 1990 model year are marked green at the plug connector and have a coil resistance of 2.5 ohms.
Important: to avoid faults and damage to the injection valves and control units use the brown injector valves only with control unit with part number 944 618 124 05 (from 91).
The green injection valves must never be used with the DME control unit with part number 944 618 124 05 but only with the control unit with part number 944 618 124 02 (until 90 ).
Also, for 91 model year the circuit plate switch by which the fuel/ignition characteristics could be influenced is now deleted because of the anti-knock and adaptive lambda control. The familiar coding options with the coding plug remain unchanged. Introduction of the "Check Engine" lamp has been made possible . However the lamp is only fitted in the USA and Canada versions."

Mark944na86

Thanks Peter -- that's very useful info. My faith in the list has been restored (I'm sorry I ever doubted you all...)

It seems that with the change of injectors, the fuel maps for the two DMEs may well be different. The earlier injectors (944.606.112.01, OEM Bosch part # 0 280 150 811) are rated at 29.2 lb/hr. I haven't definitely tracked down the Bosch OEM part # for the later injectors (Porsche part # is 944.606.120.00. Bosch part # might be either 0 280 150 003 or 0 280 155 003.) The 0 280 150 003 is rated at 37.3 lb/hr, haven't seen a number for the 0 280 155 003 (not even sure it exists.)

At any rate, I think it would be foolish for me to assume that the EPROM for one DME could be expected to work in the other. So I'm going to give the chip advertised as a "Weltmeister" a wide berth. It says it's intended for a 90-92 S2, but Weltmeister says (I phoned them) they only ever produced a chip for the 89-90 S2.

So who knows what this guy is selling. Probably he doesn't even have a clue -- some pirated chip from who knows where.

The joys of eBay...

Thanks all -- particularly Peter. I appreciate the effort getting that text in!

-Mark