teske

I have a 95' 993 and want to put the in another chip. Once the DME is out of the car and the lid is removed, how can you tell which electronic device above the board is the OEM chip that I will be replacing.

Does the OEM chip have recognizable characteristics? Like certain #s or other distinguishing markings? I assume from what I have gathered it unplugs directly from the board. Is this true?

It would be greatly appreciated if someone could please attach a close up picture or pictures of the chip, and where it is situated on the board or boards in the Motronic box.

Are all OEM chips in the 993 the same, or is the '95s appearance unique to that year? If appearance is the same, is the mapping for all the years pretty much the same also?

Thanks for any help!
Paul Teske
'95 Polar Silver Carrera Coupe
'78 Guards Red 911SC

JasonAndreas

The MY95 EPROM (27C512) is unique to that year. MY96 came with a OTP (one-time programmable) ROM and MY97-98 has an EEPROM (flash).

For the most part the fuel & timing maps are the same between model years. There are little tweaks for varioram but not much else. Code wise there are a LOT of differences.

c993k

You just can't use any generic IC and expect miracles.
It's best that you get one that's specific for your car then get it on a Dyno and reprogram it.
Makes a huge difference, especially if you have a few mods like cams and exhaust or a bit of head work.
Hope this helps, good luck. Chris

teske

Thanks for the information and pictures!
Paul Teske

teske

I just went out to llok at the box open on the work bench. There is a device in the location indicated in the pictures with the number M27C512 ..then a sequence as follows: -10F1 8881A 0032K Singapore. To the side is a Brand icon that looks like an italizied ST.

Is this a stock chip for the MY95 ( the M27C512 does match) or does the other info mean anything that would lead one to think it was not the OEM chip? Would just like to know whats in the car now?

Thanks
Paul

kb

Could you post a picture of your set up? Will be easier for someone to provide you with info you need. Not being rude - just a suggestion.

rkam

M27 Device type
C 5Volt Supply Voltage
512 512Kbit (64Kb x 8)
-10 100ns Speed
F FDIP28W Package (Shape of eprom)
1 0 to 70 Temperature Range in degree Celcius

This is probably a standard chip, but it is possible to remove it, erase it and reprogram it.

Datasheet found at st homepage. (I am not allowed to post links)

Edit: typing error.

JasonAndreas

I would be really surprised if Porsche or any automotive manufacturer supplied their cars with narrow (0-70C) temperature range ICs. Usually any chips used in a car have a minimum temperature rating of at least -45C!

rkam

The fact that this seem to be a standard chip could as JasonAndreas suggests mean that somebody have replaced the chip with an easily available eprom.

My own eprom has only a Bosch number B57701 in addition to M27C256 and the top is covered with a label with a Bosch software number.

I don't know how temperature affects the eprom. It could be OK at other temperatures. Slower?
Somebody who knows they have a standard chip should check if they have similar temperature range.