Check It Out! OEM, Autothority, Weltmeister chip maps!

[Steve W]

Those of you with '84 to '89 Motronic equipped Carreras may have wondered what the differences in fuel mapping between some of the different popular chips for our cars are. I pulled it off three different chips I have with a eprom reader/programmer and used a program to disassemble the code and map the fuel values shown here.

The first graph is that off the original Porsche chip from my '84 non-California equipped Carrera. California cars were even more conservatively mapped and so are a 1/2 sec. slower, however I don't own my '84 California Targa anymore so I can't map it. There is also a mapping for full throttle. Full throttle is when the throttle switch of the Motronic is tripped closed, when past 75%-80% open, and a fixed fuel map is engaged. In this situation, the O2 sensor is ignored and a fixed fuel quantity is injected. If your car has been modified via intake or exhaust modifications, and this timing is not increased, you will not notice a significant increase in power, for the amount of power you generate is generally proportional to the fuel you burn.

The second is that of an Autothority chip. Its rev limiter is set at 7040. The third is that of a Weltmeister chip with a 6840 limit. What is interesting about the Weltmeister chip is that it was originally a Dinan Engineering chip, as evidenced by the letters 'Dinan Engineering' I found in parts of its hexadecimal code.

Quick code examination reveals that Autothority is actually coded a bit more aggressively (richer) at the top end while the Weltmeister is coded a bit richer on the low end.

[dickster]

i'm impressed

way over my head of course

but seems like it could be straightforward with the right kit

richard

[Siena911]

This is neat!!!, makes for an interesting read.

Am I right in my understanding that the percentage values on the rhs of the data represent the value of the throttle position i.e. 10, 12, 15% open etc...

With all of this, is there a maximum length of time that an injector can remain open? i.e. you don't want the injector injecting when the inlet valve is closed?

Another thing, are the injectors either fully open and then fully closed or can injectors be gradually opened, i.e. 20, 30 or 40% of the full value?

Cheers Jakes

[Kurt B]

This is the kind of data that desperately needs to be archived...someone put that in the 911 information pages, seriously.
I'll have to give it a long think tonight when I get home...try and figure out what it all means. I have weltmeister.

[ChrisBennet]

Just for fun, I've been trying to reverse engineer this stuff from scratch. I can send you a .BIN or .HEX file from an '89 DME if you'd like to compare.
Chris

[falcon]

Need help guys. When I try opening the .gif file it give me a file format error. What program(s) can I use to open these files.

[widebody911]

It's because there's spaces in the file names - some programs don't handle this well.

Originally posted by falcon
Need help guys. When I try opening the .gif file it give me a file format error. What program(s) can I use to open these files.

[nhromyak]

Rember the 84-86 did NOT have a knock sensor. The 87-89 did. They also got the higher compression, and probably the reason for the more aggresive ignition timing. Then when knock is detected, they get retarded.

Just my .02

[Joeaksa]

Steve,

If you have the ability to "look into" the data programmed in the chips, is there anyway I could pay you to check out my chip?

It was purchased off of the internet used and my main concern is that the RPM limit may be higher than I like (above 7100!) and that my limits may be the rod bolts! There is a name on the puppy but evidently its someone who has gone out of business. I placed a notice on Pelican a year ago and no one had heard of the company.

Would be happy to pay you to check this out if you would have time. I have an extra stock chip and could put this in the car to drive it in the interim.

TIA,

Joe

[Clark Griswald]

Actually no knock sensors on the later 3.2s. First knock sensors appeared when the 3.6 showed up.

[Steve W]

Hi Joe,

I would be glad to dump the eprom mapping your chip or anyone's chip for that matter and send you the results, along with emailing you the bin file. If I get enough samples, I could post them up on a web page for everyone to reference and compare. I can do it for you or anyone for the basic cost returning your chip via USPS Priority Shipping and insurance if desired. Email me at stevekw@pacbell.net to make arrangements.

[ChrisBennet]

Joeaksa,
The "distrial" program for dumping the chip contents is available from Protomotive. Go to their web sight and download it.
http://www.netquest.net/~knighton/software.htm
Have fun.

nhromyak,
The difference between the early (US) 3.2s and later ones was pretty much just the DME. No knock sensors or compression differences.

Chris

[Joeaksa]

Steve,

Thanks much! Will email directly.

Chris,

I would do it myself but no EPROM reader! I am an old "heathkit" kind of guy and love to chase sparks but have never played with chips.

Would love to learn though!

Joe

[Oliver911]

Ok I must be missing something really simple, I have distrial, but how do I open a binary file with it. I'll post the map of the autothority mass air flow chip.
Thanks

[svlTarga]

I've got a '88 CA car. I didn't know that the CA cars were different then the rest of the US. 1/2 sec, hmmm.

I used to be a hardware designer but since the current job is Software only, I don't have direct access to a EPROM reader. I'm trying to hook up with someone who does and I'll pull the chip and send it on as well.

Do you have copies of the ROW PROMs? I know that they had a higher HP rating and most of it was in the programming. I would love to see how those maps compared.

[wolfrpi]

Steve - is there any way to burn new chips with the distrial system as it is available to the public? Or is the save feature a limiting factor in the burning? Thanks.

[wolfrpi]

Much thanks

[ChrisBennet]

In case any of you are interested in this sort of thing I put the results of some my investigations up on my web site.

http://members.rennlist.com/messinwith911s/DMEHacking.htm

Many thanks to Steve W for starting this thread!
Chris

Key words: Motronic, DME, Carrera, EPROM