Yet Another Cheap DME Replacement

[Tim Polzin]

Edited on November 8, 2004. Before considering this mod, read what Chris Bennet has said below.

Thanks..Tim

As noted from past posts, a few of us have been playing around with various DMEs. We know the 85.5-87 944 DME can be made to work in the 911. Now here is another.

The DME was from a BMW 535is, which is a six. Bosch # 0 261 200 059

Externally, the unit is identical to the 911. Internally, the date codes are all around 89 and it seems to have a later version of the 911 PC boards. It uses the 28 pin EPROM and the other chips bascially seem all the same. Now, the interesting stuff. With the BMW EPROM still installed, the car started and ran at idle. Not knowing what the advance or fuel tables were like, I did not want to actually drive it with that chip. With the 87-88 Porsche EPROM installed, it ran perfectly. This box seems to be a direct plug in replacement for the 911 DME. The only difference I noticed was that the shift light came on at redline instead of at shift point. The rev limiter worked as it should, and the light came on at about 200-300 RPM below cut off. Interesting. I'm not sure if the difference is significant, may just be a jumper.

The best part of the whole thing is that I paid $12.00 for the DME (plus shipping)! I've seen them irregularily on EBay and they go usually for less than $60. Might be a cheap way to test performance mods to the EPROM without hacking our precious 911 DMEs. Certainly a cheap way to have a spare in the trunk.

Cheers....Tim

[emcon5]

Originally posted by Tim Polzin The only difference I noticed was that the shift light came on at redline instead of at shift point.

In my opinion, that is where it ought to come on.

Tom

[Steve W]

That's awesome Tim. Makes I wonder how difficult it would be to take a DME from a car with a Bosch hot wire air mass meter instead of our restrictive air flapper meter and replace our boxes with that along with the hot wire meter into our cars.

Some BMWs had speed limiters programmed in. I don't know which models though. Maybe it's also time to test the top speed of your car. Got to make sure it hits 149 mph!

[Jim T]

The 059 is not only for the 87/88 535is, but also for the 86-88 535i models (which are more plentiful than the 535is). Maybe also for the 1985 535i.

I only point that out so that if you search for one, you don't limit your search to the 535is model.

[Tim Polzin]

Steve:

Good question. But the later DMEs have an extra row of pins on the connector, so the process would not be too simple. I'd be more interested in seeing how the 944 Turbo's KLR knock sensor ties into the DME.

Jim:

Thanks for the update. I was clueless as far as what BMW's have what DME.

I also was thinking about the lack of a shift light. If the DME was from an automatic, would it still have a shift indicator? Perhaps it may just be a jumper, although as Tom said, it may be more useful this way.

Tim

[ChrisBennet]

Since this was posted back in 2002 more info has come to light. It turns out there is more than one "flavor" of BMW '059 DME. Some will work (28pin seem to) and some won't. Some 24 pin flavors won't work even when converted to 28 pin.
Out of 5 24->28 pin conversions I've done or know of, only 3 have been "successful". Because the circuitry is different between these and the Porsche DME's I would confirm that the mixture is what you expect.
-Chris

[Tim Polzin]

Chris's comments are on the money. Looks like I might have found a 30% solution. A 28 pin DME may work, but the 24 pin is iffy.

Tim

[Joeaksa]

Very good work! Now, what DME unit will interface with the 964 model cars?? Believe that the computers are way different.

Thanks,

JoeA

[scottb]

Steve W: Would one of your 911 chips work with the BMW box?

[Joeaksa]

Scott,

Would not look at it so much as a "BMW or 911" box but its a Bosch Fuel Injection computer and would feel that anyone's chip would work in it if its the same type of unit.

Granted later mods may make this statement invalid but from Tim's work above it sure looks like the DME computer from various cars that use the Bosch FI system will work in all of our cars.

Joe

[scottb]

I love threads like this one....where someone figures out a way to avoid the "Porsche tax."

Nice going, Tim!

[Tim Polzin]

Gang, please re-read this post. There is only a chance that it will work, and even then, only likely with a 28 pin "059" box. It probably is not worth the effort.

Tim

[Jim Garfield]

Great work Tim. I hope that I won't need it, but thanks if I do.

[Joeaksa]

Tim,

For a price of $12 or so, I will take a lot of chances!

This is a fuel injection computer from Bosch, not something that Porsche made. Bosch will not make a totally different unit for each car, but hopefully change chips to fit each application.

Thanks,

Joe A

[Lorenfb]

"Granted later mods may make this statement invalid but from Tim's work above it sure looks like the DME computer from various cars that use the Bosch FI system will work in all of our cars. "

Not true! You might want to look MORE closely at ALL the various outputs and how
they REALLY are implemented & function. There're many differences between the
boxes.

[Wayne 962]

This is a related, and useful tech article that most of you probably haven't seen:

http://www.pelicanparts.com/bmw/techarticles/E36-DME-Repair/E36-DME-Repair.htm

-Wayne

[Joeaksa]

Loren,

Considering that you might have a bit more experience than most with DME boxes, are there any other Bosch DME units that will work with the 964 systems?

Wayne, very good article on the various units. Now we need to figure out which ones work in Porsche's!

Thx,

Joe A

[Lorenfb]

The 964 unit is unique as it has complex on-board diagnostics ONLY for a 964.

A VW crank looks and probably fits a 356 engine. Would you use it?

Don't waste your time trying to find alternate compatible Porsche DME units,
each is different for different functionalities. That's why Bosch has different
designs for each manufacturers' cars. Some of the DME "families" are the
same, but some of the circuitry is usually different.

Check out this web site (www.systemsc.com) on the Parts page for more info
on the Porsche DMEs.

[ausgezeichnet]

I have an 84 3.2L that I suspect my have a bad DME. Since the 84's have 24 pin chips, I was wondering of any one knows if the DME from a 85-87 BMW 535i/is would work. The part number is 0 261 200 059 Bosch Motronic M1.0 Adaptive (24 pin)

My other option is to try the 28 pin version from an 88. The part number 0 261 200 059 Bosch Motronic M1.0 Adaptive (28 pin). In that case I would need a 28 pin chip. What do people do with their stock chips when they upgrade. I've never seen any for sale. Thanks.

[DonMo]

I am running a 28 pin 88 DME in my 84 Carerra, no problem. Be sure to set your idle accordingly.