10 mpg 3.2 - can’t find where the fuel is going

[mysocal911]

Originally Posted by Discseven

Dave... there's not a single Porsche/Bosch sticker on exterior of the box anywhere. Only one is the one I put to indicate the date it was tested and by who. Anything inside you want referenced?
.

Well, this is a problem! It may be a converted 944 ECM and have circuit board problems. You once indicated it was "rebuilt", e.g. Vertex, ECU Docs, ProgRama, that's a problem too.
They may have bridged circuit tracks, it happens! Without fully testing the DME ECM before installing it in your vehicle with a replace chip, is not a good idea.
You need to talk to Systems Consulting (systemsc.com).

[Discseven]

Originally Posted by mysocal911

Well, this is a problem! It may be a converted 944 ECM and have circuit board problems. You once indicated it was "rebuilt", e.g. Vertex, ECU Docs, ProgRama, that's a problem too.
They may have bridged circuit tracks, it happens! Without fully testing the DME ECM before installing it in your vehicle with a replace chip, is not a good idea.
You need to talk to Systems Consulting (systemsc.com).

Dave... Understood. Will call SC Monday.
.

[Discseven]

Originally Posted by ant7

Just for a bit of clarity on the chips fitted to Euro, or in my case UK DME/ECU.
Hope this helps.
Ant.

Ant... Is that your driven ECU with the "Euro" (ROW?) chip 1267355181? What's the chip to the left of it on the black box, the ...027?
.

[proporsche]

Karl i have these 2 chips from 1988 us carrera if you like one you can have it for free.if you going to be updated you ecu..

Ivan

[silverlock]

Originally Posted by Discseven

Dave... Understood. Will call SC Monday.
.

Note that System SC is Dave’s shop.

[ant7]

Karl,
Its a bit of a long winded story, but here's the short version; The chip on the left is the original from my UK 1985 year ECU [currently in my car running a SW chip] the one on the right was the original chip that came from the ECU that was in my car when I got it some 14 years ago now, which should be a Euro spec, however; I was informed that this chip was designated for low quality Gas, so not original for UK cars ??? I guess there are some here who could verify that.
Hope this helps.
Ant.

Originally Posted by Discseven

Ant... Is that your driven ECU with the "Euro" (ROW?) chip 1267355181? What's the chip to the left of it on the black box, the ...027?
.

[Discseven]

Originally Posted by proporsche

Karl i have these 2 chips from 1988 us carrera if you like one you can have it for free.if you going to be updated you ecu..

Ian... You know I appreciate this.

Originally Posted by ant7

Karl,
Its a bit of a long winded story, but here's the short version; The chip on the left is the original from my UK 1985 year ECU [currently in my car running a SW chip] the one on the right was the original chip that came from the ECU that was in my car when I got it some 14 years ago now, which should be a Euro spec, however; I was informed that this chip was designated for low quality Gas, so not original for UK cars ??? I guess there are some here who could verify that.
Hope this helps.
Ant.

Ant... Yes, thank you. I'm gaining insight to what chips belong where.
.

[ischmitz]

wow - looks like I am late to this party - here are some simple facts:

To my knowledge 0.261.200.050 is a Euro DME if it comes with the 1.267.355.180 chip. That version of software does not process the O2 sensor signal even if the hardware is present inside the DME. Tried, tested and confirmed.

And while the EPROM itself is a 4kB chip the code is actually only 2kb. The second part of the chip either contains an identical copy or it's empty. The 2kb is mostly maps and constants and jump tables. The base code resides on the Intel MCU. It is a custom mask-programmed version that is common to all 911 DME boxes and contains 4kb of universal code. Think of it like an OS with application data in the EPROM.

Later DMEs with the 8kb 28-pin EPROM disable the internal code section of the MCU and the entire code resides on the EPROM. Pretty simple.

Further, you can convert a 944 DME into a 911 DME. It's a pretty simple process if you know what you're doing.

[mysocal911]

Originally Posted by ischmitz

wow - looks like I am late to this party - here are some simple facts:

To my knowledge 0.261.200.050 is a Euro DME if it comes with the 1.267.355.180 chip. That version of software does not process the O2 sensor signal even if the hardware is present inside the DME. Tried, tested and confirmed.

And while the EPROM itself is a 4kB chip the code is actually only 2kb. The second part of the chip either contains an identical copy or it's empty. The 2kb is mostly maps and constants and jump tables. The base code resides on the Intel MCU. It is a custom mask-programmed version that is common to all 911 DME boxes and contains 4kb of universal code. Think of it like an OS with application data in the EPROM.

Later DMEs with the 8kb 28-pin EPROM disable the internal code section of the MCU and the entire code resides on the EPROM. Pretty simple.

Further, you can convert a 944 DME into a 911 DME. It's a pretty simple process if you know what you're doing.

The poster at post 208 disagrees;

that's not a Euro chip. It's a stock chip commonly found in in all US and Canadian 85-86 3.2s.

[ischmitz]

You're a funny guy Loren. Look at the bright side, no one has blamed an "out-of-spec" transistor as root cause yet...

[Steve W]

So just to save everyone time on what is a wild goose chase. So much bad information here. A factory Euro chip will not cause the car to drop to 10 MPG. I'm sure any Euro/ROW owner here can verify that. There is almost no difference in MPG between a US vs Euro car, maybe 1 or 2 mpg at worst, if one car is out of tune. It's a different story if you put a US chip in a Euro box, but I won't get into that as that's not the situation here.

Originally Posted by ant7

Just for a bit of clarity on the chips fitted to Euro, or in my case UK DME/ECU.
Hope this helps.
Ant.

Ant, the above are both standard chips from an 84-86 ROW/Euro car. There is no difference between the two, mappings are identical. The 027 chip programmed on a 2k memory chip is commonly found in the earlier of the series, and the 181 on a 4k memory chip and found in some of the later ones.

Originally Posted by proporsche

Karl i have these 2 chips from 1988 us carrera if you like one you can have it for free if you going to be updated you ecu..

Ivan

Ivan you must have chipped a couple of 993s before? The above chips won't work on a 3.2, as they are from an immobilized 993.

Originally Posted by ischmitz

wow - looks like I am late to this party - here are some simple facts:

To my knowledge 0.261.200.050 is a Euro DME if it comes with the 1.267.355.180 chip. That version of software does not process the O2 sensor signal even if the hardware is present inside the DME. Tried, tested and confirmed.

84-86 ROW DMEs are typically 0.261.200.051 (911.618.111.04 or 06 or 07), while the US cars are 0.261.200.050 (911.618.111.05). 0.261.200.050 is not a Euro DME, and 84-86 Euro units typically come with the chips Ant has. And I'm repeating myself here but the 1267355180 chip is not a Euro chip but is the standard chip found in all 86 and some 85 cars and processes an O2 signal. If the unit you have does not process the O2 signal then you either have a unit with a missing or failed O2 circuit, or your wideband sensor, if that's what you're using to verify, is not working.

But what do I know? I only have an original USA 86 3.2 here with its original 1267355180 chip and been doing this since 2001 so you can either go with what this construction worker is saying, or that of that TV repair tech out of the pie hole city of Lomita, or perhaps the factory service manual. Excuse the poor screenshots, taken from POSES on a PIWIS2:






What is the conclusion of all this? Based on what Karl found, it's likely the DME unit is faulty. Although Pelican Parts, who hosts this forum, provides the service to repair these units, I'm sure there's more than one individual here waiting to snatch the job. Best of luck!

[ischmitz]

and just like that the thread is going south and the name-calling starts

[Steve W]

Well Ingo if you're so confident, I'll offer you the same bet that I did to Dave of Lomita. Pink slips, your 911 against any of mine. And Dave, I'm still waiting for your answer ... well?

[ischmitz]

Use Ghidra or IDAPro and look at the 8051 code

[Steve W]

Well apparently your files must be misnamed or you're not looking hard enough. The simple way is all one needs to do is put a wideband analyzer in the exhaust and monitor the Lambda ratios at idle, part throttle and cruise. Disconnect the O2 and you'll see the AFR/Lambda all over the place. Reconnect and you'll see it lock down to Lambda 1.0 or 14.7 AFR.

[proporsche]

Steve W..thanx a lot i was always wondering about those chips.Yes i did some chip changes in LA about 18 years ago and way too many beers ago to remember;-)

Keep up the good work Steve.

Ivan

[mysocal911]

Karl's #173 post explains in detail what was happening after he received a loaner;

According to Dean, his ECU is an ‘87 box that works fine with his ‘86 engine. Unit’s been checked by Ingo Schmitz who upgraded it to a 28 pin.

Although Karl's ECU operates closed-loop with the 180 chip, it runs richer than the later (last) 911 3.2 U.S chip (8K) of the loaner from Ingo.

It's that simple!

[Steve W]

Originally Posted by mysocal911

Karl's #173 post explains in detail what was happening after he received a loaner;


Although Karl's ECU operates closed-loop with the 180 chip, it runs richer than the later (last) 911 3.2 U.S chip (8K) of the loaner from Ingo.

It's that simple!

What, so you're now conceding that the 180 chip runs closed-loop so is thus not a Euro chip?! Isn't that what I've been saying? Of course Karl's unit runs richer because there's something wrong with his unit - reread post #232 - t's not because of the 180 chip. Your logic skills and that of some posters here just astounds me, it's like reasoning with a wall, a huge time suck. I'm out, you guys have at it,

[mysocal911]

The S100 chip (339 quad comparator) two (of 4) outputs drive the 8051 two interrupts to either cause the fuel mixture to become lean or rich momentarily,
based on the O2 sensor's input (pin 24) voltage to the DME ECM. The way the S100 inputs are biased (resistors) can affect the Lambda, e.g. a value greater than 1.0.
Most likely, it's just the two interrupt subroutines of the EPROM which determine what the average Lambda will be.

Note: Remember some Euro chips run closed-loop too! Understanding digital/analog electronics and repairing a DME ECU isn't as simple as changing map cells
in an EPROM - "performance" tuning, as we've learned from naive posts of some.

[ant7]

Sad to see this thread go the way of many others on this subject, some very useful info has been submitted here though' by those with extensive experience and knowledge of these old ECU's.
Good luck with the car Karl
Ant.