DME Chip Problem

[Lorenfb]

The circled area indicates the component difference between the USA and the
EURO DME ECM, i.e. the O2 system. The EURO DME is the upper image without
the components.

[Hendog]

Originally posted by Lorenfb
At this point it's best to convert it to a 28 pin DME ECM which is basically
what a performance chip attempts to do.

Bottom line: All 3.2 DME ECMs should be converted to a late 28 pin DME ECM
and not waste money with 24 pin performance chips. .

It's been a while since I looked inside the box, but I know I have a 24 pin. Was the board manufactured with the extra 4 holes to accomodate a 28 pin chip in 1987? Were they moving in that direction at that time?

[Lorenfb]

"Was the board manufactured with the extra 4 holes to accomodate a 28 pin chip in 1987? Were they moving in that direction at that time?"

Yes to both.

[Hendog]

Originally posted by Lorenfb
"Was the board manufactured with the extra 4 holes to accomodate a 28 pin chip in 1987? Were they moving in that direction at that time?"

Yes to both.

How much work is involved in updating the board to accomodate a 28 pin chip? I make my living with a soldering iron .

[ToddM]

get a 28 pin DIP socket, remove the old 24 pin DIP socket, and install the pin DIP socket. The PCB is the same for both versions so the extra holes are there to accomodat eit already.

[Por_sha911]

Originally posted by Lorenfb


The circled area indicated the component difference between the USA and the
EURO DME ECM, i.e. the O2 system.

Which is the Euro?

[Lorenfb]

"Which is the Euro?"

The upper image is the Euro.

[jbrinkley]

gosh.......... I feel bad, I have three 24pin chips

[Steve W]

Before anyone feels bad, some of the information presented here is seriously erroneous and needs correction.

a) there is no advantage going from 24 to 28 pin. The coding is identical. In the 24 pin setup, On the U.S cars, once you convert from 2k to 4k, and use the appropriate chip, there is absolutely no difference between that and a 28 pin chip - the programs are identical. On the European cars, it is a waste of time and makes absolutely no difference going from 2k to 4k, or converting to 28 pin.

b) you do not want to convert a 24 pin Euro box to 28 pin. Not only is there no advantage, but you start causing more confusion, as you will need to configure additional wiring and need a Porsche part adapter to select the correct Euro spec map in the 28 pin program, which again is idential to the original Euro spec 2k program. Without proper configuration and the necessary adapter, it will be running the default U.S. maps.

c) There are some major difference between a Euro and US chip. A Euro chip will not recognize the O2 sensor, and without going into excess detail, because of the differences in the fuel and ignition maps, it responds and performs differently.

Joe, I take you got my reply to your email, but if not, basically it does not sound like a big deal what your friend did and should be salvagable, but for now, he should not be within 50 feet of that DME with a soldering iron(or any power tools for that matter). He ripped the original soldered in chip out of the board. I would have a 24 pin socket put in and another copy of the proper Euro chip installed. The rpm limit sounds like a rpm sensor issue.

[Lorenfb]

"there is no advantage going from 24 to 28 pin. The coding is identical"

Please! Porsche/Bosch just doubled the EPROM memory (4K>8K-28pin)
because they just wanted to make manufacturing production
changes without any benefit. RIGHT! It has been posted on Pelican
Parts by others about the switch to the 28 pin EPROM and its benefit
early on when Pelican first started the web site. These benefits have
been posted before on this thread. It's very obvious that the above
statement is indicative of a lack of understanding of the 8051up and
its memory addressing modes and how the 3.2 DME ECM really operates.

"you do not want to convert a 24 pin Euro box to 28 pin. Not only is there no advantage, but you start causing more confusion, as you will need to configure additional wiring"

Totally incorrect as those who have exchanged late DMEs with
early DMEs in an early car did it WITHOUT wiring changes.
That's the purpose of having a socketed EPROM, i.e. to make production
upgrades without making major production changes (wiring).

"need a Porsche part adapter to select the correct Euro spec map in the 28 pin program"

More misinformation! Porsche shops have been exchanging Euro & USA chips
wihout any "part adapter" (Do what??????) for over 20 years in both DMEs.
THAT'S THE PURPOSE OF USING AN EPROM!!!!!!!!!!!!!!!!!! Versus using a
fixed coded (no changeable firmware) microcontroller (ECM). Bosch just
changed the EPROM for various markets, e.g. ROW or USA/Japan, which
was also the case for basically all the 964 DMEs. There's NO such thing as
a "part adapter", i.e. more hyperbole.

"Euro chip will not recognize the O2 sensor, and without going into excess detail"

So!!! All who really understand the 3.2 911 are quite aware of this.
Guys running a Euro DME couldn't care less about the O2 sensor anyway.
As was posted before, the Euro & USA maps are basically the same.
And, "excess detail", like what??? More hyperbole maybe? Please!

Bottom line: The upgrade to a late 28 pin DME ECM is significant
as has been verified by all Porsche shops that have used a late
DME in an early car. This has been known for over 15 years now,
but for some may be not. Many knowledgeable Pelican guys
who have been involved with 911s over the years are aware
of this too. Many Porsche shops request this upgrade when
their customers' DMEs require rebuliding, as a value-added benefit
without the problematic issues of a performance chip.

Actually, the 28 pin EPROM setup allows the 3.2 DME ECM with
the proper EPROM to have diagnostics and a CEL (check engine
light). Just take a look at the DME schematic. It's all there!
As mentioned by another poster, Porsche/Bosch was thinking ahead
when the 3.2 DME ECM was initially developed.

[Steve W]

Well, since you seem come off as such a expert, why don't you tell us all specifically what is the advantage of going from 24 to 28 pin - and no technobabble jibberish assumptions. List exactly what are the performance differences and why. Without real facts, your statements have no merit. I heard it so because someone told me so doesn't count.

And of course there is a difference between a U.S. and Euro chip, or I would not state so. I am not here to teach a chip programming class, so if you don't know the differences, and don't like my clarifications, too bad.

Over the years, many of your past posts are so full of errors and misleading information, you should be prohibited as making erroneous statements as a self proclaimed expert is the most dangerous of all. I could post links to many of them, but I don't have that kind of time. If you only heard all laughs and jokes from shop, tuners, and manufacturers regarding the errors of your posts.

[Nine9six]

Ahh, forget about all this and just change the plug wires. That oughta git er done.
Sorry fellas, I couldnt resist.

[MattAlpha]

On a side note, once I get my suspension fixed up, I'll be purchasing one of Steve's chips. Just thought I'd mention that.

-Matt

BUY STEVE W CHIPS! BUY STEVE W CHIPS. ISNT THAT EASY TO SAY! HAVE A NICE DAY!

[ToddM]

I think the real laughable thing about all of this is that somebody looked at something, thought it looked weird, and completely pried it out of it's PCB when it had zero issue and was probably stock from the factory.


Makes you really think before buy ANY used car.. just what dolt(s) owned it previously

[theiceman]

Do Steve and Loren agree on anything ? seams like two very knowlegeable guys with differing opinions, if they were to work together in the analysis we would all be better off.

[scottb]

Originally posted by theiceman
.... if they were to work together in the analysis ...

That's about as likely as the Israelis and Iranians working together to achieve Mid-East peace!

[88-diamondblue]

Iceman,

Getting helpful information from Loren is a feat all in it's own. There are the derogatory comments and the rhetoric that goes with it. The discussion has been had about "if you have the information" why not share that info. Steve W has done that clearly and concisely when ever help was asked of him. His technical support is awesome as well. I know where my trust is and many others are on this issue.

Do a search on "chips" and read a few of them since there will be many. Loren has attacked Steve so many times that it has has just become ridiculous. He also has been temporarily banned here and at Rennlist for his bad behavior. Other posts at Rennlist were sent to the abyss by the mods because of nasty posts. Grab a brew or two and start reading, you will understand more about it.

[Flyer88]

Originally posted by Nashville84Cab
Hey Joe,

Besides the incurred chip problem, sounds like your friend is experiencing issues with the speed sensor. After getting the chip/DME problem fixed, I would suggest him to take a look at the gapping between the speed sensor and the fly wheel.

I spent alot of money, headaches, and time chasing the exact problem (replaced DME chip, DME itself, plugs, wires, cht, AFM, most ignition related parts, and even new Speed and Ref sensors). It turned out that my speed sensor was gapped to close to the fly wheel and causing a misfire that acted like a rev limiter at the exact RPM every time (~4800).

If he has no luck finding ROW DME or repairing his, I do have my extra DME if he wants it. I was planning on keeping it, but I guess there really is no need for it anymore as my Rev Limiter problem was the speed sensor gap. And Steve, the chip is awesome - going to Mid-Ohio in 10 days and can't wait to give it a workout with all systems performing correctly!

BTW, your friend will be amazed at the difference in HP between RPM's at 5600 vs redline (near).

I bet Steve Wong could repair and make a chip for the Euro 3.2. I just reinstalled my Autothority MAS with Steve's chip for it and it runs very strong!

Good luck,
Darrell

I agree with Darrel on the crank sensors. I was having a "jumping" issue under hard acceleration and had replaced the cap, rotor, wires, plugs, O2 sensor, and WOT sensor (all after having replaced the clutch and installing a Steve Wong chip in a 24 pin DME). Turns out one of the crank sensors was bad - replaced it with a used part (for now) and it runs stronger than ever. BTW my wrench informed me that BMWs use the same sensors (with a 3" longer wire) and they sell for 1/2 the price.

[Nashville84Cab]

Originally posted by Flyer88
I agree with Darrel on the crank sensors. Turns out one of the crank sensors was bad - replaced it with a used part (for now) and it runs stronger than ever. BTW my wrench informed me that BMWs use the same sensors (with a 3" longer wire) and they sell for 1/2 the price.

Yup I think someone else here purchased the BMW sensor, but never really confirmed if it worked the same... but my guess is that it will work (looks like an identical Bosch part).

But before your friend goes purchasing and replacing parts, I would recommend he first swap the speed sensor (aka rpm sensor) and the reference sensor (same part) to see if the speed sensor is actually working. If you get a no start, then the possible problem is that the swapped sensor is bad. If you still get the "rev limiter" then from my experience, the gapping on the speed sensor is slightly off and not magnetically picking up the flywheel teeth at the higher rpm... hence the rev limiter. In my situation, my speed sensor was too close to the flywheel. Did he have a recent work on flywheel or tranny?

BTW, I should give credit where credit is due: I had called Steve Wong about getting one of his chips to solve my rev limit problem (perhaps thinking the same as your friend in that the DME or chip is the problem as a last resort) and Steve told me that the problem is not with my current chip nor DME, but with the speed sensor... he was right (as he and Flyer88 mentioned in this post)!

After replacing many parts, I now have extra speed and ref sensors if your friend needs them.

Best regards,
Darrell