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Question Difference between 944 DME ECU's.

I have an 87 non-turbo 944 that is refusing to start.

I've got no pulse and no spark. My tach bounces slightly when cranking, and I've even jumpered the appropriate ports where the DME Relay plugs in to ensure the fuel pump runs... I've got fuel at the rail, but still no spark or pulse from the injectors...

Okay, so with that out of the way - What's the difference between the 944 DME ECU's with a black label and those with the beige label?

I pulled the ECU from my non-turbo car, and it has a beige label. Is that the correct ECU? Could it be possible the previous owner replaced it with the wrong one?

Thanks for any help - I'm still learning all there is to know about the 944.
Old 03-24-2009, 07:42 AM
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The label isn't as important as the insides.

See if this helps: http://www.the944.com/88_to_86.htm
Also: http://www.the944.com/dme.htm

You're right on the line of when they changed the chip in the DME. I've never messed with removing mine, so maybe some other folks can provide additional insight.
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Old 03-24-2009, 08:19 AM
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The 944S and the Turbo DME will not work with your car
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Old 03-24-2009, 04:17 PM
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there is a voltage difference with AFM/DME starting in 85.5, IIRC. someone is sure to chime in.

what you need to verify is the part number and cross reference that with the year of your vehicle. there are sure to be other years' DME's that will work with your vehicle. more history with the problem may be helpful.

i see this is your first post, let me be the first to say WELCOME to the FORUM!
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Old 03-24-2009, 04:25 PM
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Well, this ECU's numbers are as follows:

0 261 200 077
944.618.121.04
944 MWN-01

I should probably slap myself for not including them in the original post.
Old 03-24-2009, 05:33 PM
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From looking at those pages, I've found that my ECU has the 24 pin EEPROM port.

I have a suspicious black mark on the back side of the ECU board, beneath the long chip, which is beside the EEPROM. Here's a pic:



Any thoughts? Is it a burned chip, or is it simply a heat mark? It makes me think the chip is dead. The other side of the board appears normal.
Old 03-24-2009, 05:55 PM
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pull the chip and check the bottom side.
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Old 03-24-2009, 06:08 PM
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just while DME s are being discussed, anyone know if a ROW early 944 DME will work on a ROW '88 924S engine? what if that 944 DME has an authority chip?
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Old 03-24-2009, 06:17 PM
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Quote:
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pull the chip and check the bottom side.
I can't pull the chip - it's soldered directly in. It doesn't have a socket like the EEPROM does. I'd have to cut it out, because de-soldering would probably cause too much heat damage.
Old 03-24-2009, 10:11 PM
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mAd924 How "early" is the 944.
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Old 03-24-2009, 10:15 PM
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Its an '83...
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Old 03-24-2009, 10:19 PM
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Quote:
Originally Posted by memoriter View Post
I can't pull the chip - it's soldered directly in. It doesn't have a socket like the EEPROM does. I'd have to cut it out, because de-soldering would probably cause too much heat damage.
i thought it was the EEPROM. sorry.

i guess it could have heat damage that discolored the board. i doubt it.

i would borrow a known good DME and see if that works to make sure the problem is the DME.
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Old 03-24-2009, 11:59 PM
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That DOES appear to be heat damage, I showed the picture to a long time friend and head mechanic (yes, I said mechanic, he's very old school, and a 944 owner) at my local Porsche dealer. He suggested that you may be able to have your local computer repair shop check the chip to see if it has burned.
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Old 03-25-2009, 04:56 AM
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Quote:
Originally Posted by 89-944NA View Post
He suggested that you may be able to have your local computer repair shop check the chip to see if it has burned.
A modern computer repair shop will not have a clue as to how to test that chip. Repair shops haven't worked on computers at the component level for a long time.
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Old 03-25-2009, 05:09 AM
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Then you better find a better shop, any one of a number of shops around here works to the component level....I had my mainboard in my laptop repaired less than a month ago
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Old 03-25-2009, 05:40 AM
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Quote:
Originally Posted by 89-944NA View Post
Then you better find a better shop, any one of a number of shops around here works to the component level....I had my mainboard in my laptop repaired less than a month ago
You can't even properly resolder many components on a modern laptop mainboard without relatively specialized equipment. TSOP and QFP packages can be soldered relatively easily with either a very steady hand or some tricks, but a lot of parts are moving towards BGA. BGA needs a reflow oven and an X-Ray machine to verify that the all the joints are good.

Replacing a connector or a socketed chip on the mainboard sure, replacing a popped capacitor maybe, but the surface mounted ICs very unlikely.

Besides, just because they know how to test a desktop or laptop motherboard, there's no reason to believe they'll have the knowledge or equipment to test a DME. You would either need a specialized harness that could simulate sensor signals and test the response (which they obviously won't have) or a logic analyzer with enough inputs to monitor the microcontroller (expensive).
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Old 03-25-2009, 06:32 AM
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memoriter.....call this guy, he REPAIRS DME's for all the Porsche shops around here, and is well know nationally......and he is reasonable.

His name is Loren (310) 545-3716 Tell him Phil at Noirtech said to call
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Old 03-25-2009, 06:53 AM
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Quote:
Originally Posted by mAd924 View Post
just while DME s are being discussed, anyone know if a ROW early 944 DME will work on a ROW '88 924S engine? what if that 944 DME has an authority chip?
The '88 944 NA and '88 924S have the same DME but it is specific for that year. Earlier DME's will not work in an '88.
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Old 03-25-2009, 08:04 AM
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Thumbs up

I must say, all of you have been quite helpful. I appreciate the information.
Old 03-25-2009, 12:47 PM
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Quote:
Originally Posted by memoriter View Post
I must say, all of you have been quite helpful. I appreciate the information.
Did you find out the correct answer by calling Loren?

I followed your post on the www.944online.com forum and you have many answers.
http://www.944online.com/cgi-bin/forum/forum.cgi?board=944-2;action=display;num=1237908862

GL
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Old 03-26-2009, 04:44 PM
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