RoW Carrera Motronic Part Number
 

I have a 1984 originally purchased in Germany (by a little old lady from Stuttgart), converted to pass US emissions in '86. I know the pre-muffler was replaced with a cat, but I'm curious to know if the computer would have been swapped out for a "US model" as well. The O2 sensor harness when I bought the car was a green wire, spliced into the computer harness, I added a yellow heater wire a few months ago but can't figure out how any of this works to begin with?!?!? Does the Euro compuer ignore the O2 sensor data? I think an excellent starting point would be if one of the Europeans out there could post their Motronic's p/n... the one I have is:

911 618 111 05

I've heard that "05" and "01" were used for US models but I cannot get any confirmation or denial that the p/n's are the same for RoW models.

When you consider that the compression is higher on this engine than the US (10.3:1 I think?), this becomes very important to me to know if I plan on updating the firmware one day.

Anyone know of any good German bone-yards or recyclers?

Was just at 20th Street Auto here in Phoenix and they have a good selection, reasonable prices and ship worldwide. More wrecked Porsches here than I have seen in years.

JoeA

I've seen both 01 and 05 on U.S. '84 Carreras, but can't comment on the first 9 numbers without looking in my car, but they probably are the same - so I don't think that would designate a European box. There were a few dmes for sale in the parts for sale forum. Do a search for dme or Motronic. There was a guy selling an '84 European box here:

http://forums.pelicanparts.com/porsche-911-used-parts-sale-wanted/67301-carrera-dme-brain-motronic-ecu.html

My experience between the 01 and 05 boxes showed that the 01 boxes had the eproms soldered in the board, whereas the 05 boxes were socketed. The computer would ignore the 02 sensor anyways if there wasn't one, but one way to know for sure if it does acknowledge a sensor if one is connected, is to disconnect the sensor, disconnect the idle control valve, lean out the mixture at the air flow meter, then reconnect the 02 sensor. If the idle changes with the sensor connected, it is obviously working.

Mine is the same model as the one listed in the classifieds and says "Made in Germany" on it as well (in English) whereas almost everything else on this car is written in German. I needed to do a metric conversion just to determine the weight, since it is listed in Kilograms!

Anyone out there ever do a US EPA conversion? I've gone through all of the cars conversion papers, I just cannot find a THING about the computer, maybe I'm overestimating the extent of the inspection and mods?

Thanks for the replies!

Btw Steve... is the mixture under the "Tamper proof" cover on the airflow meter? Mine has definitely been removed before, I assumed this was done when the O2 sensor was added. Is the t-p cover supposed to be air-tight? Guess my question is, if I start dorking around under there, will I need to replace the cover (or at least make sure the seal is good) after I replace it? Always curious about that but afraid to pull it apart to see!

The tamper plug does not seal any air passages - it's just there to keep people from randomly turning it. You don't need it if you trust yourself. You need a 2.5 or 3.0? mm allen wrench to get in there. Clockwise richens the idle mix, counterclockwise the opposite. If you want to understand and trace the Motronic wiring schematic, pick yourself up a Haynes manual for the Porsche 911 at Pep Boys.

Thanks for the info... I use the Bentley, that Porsche 911: 1965-1989 Haynes just doesn't do it for me! lol. Kind of reminds me of the chilton I had for my first car, a 1981 Mazda 626, they tried to cram in every US model Mazda ever made INCLUDING RX engines! Ironically, the Haynes I had for that car was killer. Go fig'r.

I've removed the air flow meter assembly and noticed that the "tamper proof cover" (the large black cover, not the mixture adjustment cover) had been removed and reglued back on. Being the curious type, I re-removed it to look inside and check the condition internally. The potentiometer is in there and I lightly cleaned it's tracks with a pencil eraser and then with some electronics cleaner and lubricant (the TV tuner type). It looks like the air door spring action is adjustable, there is a dial, looks something like one of those light-timer dials and it has been adjusted. I can see the wear from it's previous position?!?! Did someone _REALLY_ know what they were doing adjusting this, is this a common practice? Seems to me that by adjusting the air door tension, you are recalibrating the assumed density of the intake air (again: ?!?!?) This seems pretty f/u to me and I was thinking of reopening it and switching it back to test which way runs better (my car has always idled a bit on the rough + low rpm side). Unless one of you gurus out there can maybe explain the situation? Just for informational purposes, it appears the clamp-down was loosened and the dial rotated clockwise....

Thanks...

You can play with the black round dial in there and change the overall fuel mixture. Loosening it a click or two will richen the overall mixture in the part throttle fuel map and may tend to give a snappier throttle response because of the richened mixture and faster barn door flapper response at the expense of gas mileage. Tightening the door a click or two will lean the overall part throttle mixture, useful if your car is running too rich and you need to get your car smogged, especially with some aftermarket performance chips. If there is a O2 sensor connected, and it is working, the air/fuel mixture ratio should stabilize to stoichiometric at steady state cruise or idle. With a stock US spec Carrera, disconnecting the O2 sensor usually makes them run rich. If your car came without an O2 sensor, the grey market importer may have loosened the dial a couple of notches during the conversion.

I think there is a Pelican member here who also played with this and claims to gets good power and fuel economy. He did this by increasing the fuel pressure at the fuel pressure regulator, and tightening the dial in the air flow meter, and manually metering an air leak into the motor at cruise to get 28 mpg. The net effect should be a mixture increase at full throttle, with a leaning out of the part throttle fuel map. I have done the opposite in the past, increasing the fuel pressure from stock 37.5 to 49 psi by compressing the stock pressure regulator a bit in a press, and loosening the dial a couple of notches, increasing the richness everywhere. This was in conjunction with other mods such as exhaust, a chip, porting, and ExtrudeHoning. Now that I've figured out how to remap and burn a new chip, all that is rudimentary and unnecessary. It is better to put everything back to stock and tune the fuel maps instead.

Great info, thanks. So if I were trying to get my car back to it's original configuration, I would disconnect the o2 sensor, replace the cat with a premuffler, and reset the dial to it's old settings? Only other question, why would they adjust the mixture there instead of with the recessed mixture screw? More range?

I would probably leave the O2 sensor in for emissions and fuel efficiency, and tune everything to work as a typical US car. Try to locate an original Porsche premuffler for the best power gain. I've seen a couple of different kinds but you'll see the Porsche symbol on its exhaust flanges. Also, it may also depend on what chip is in the box. The place that did the conversion may or may not have replaced the chip in there. Look at your box to see if it has been opened before, and/or write down the number on top of the eprom chip and compare it to US ones to see if it is different.

The recessed mixture is used mostly to adjust mixture at idle and to a smaller extent, the mixture at part throttle cruise. The big dial under the cover has no influence on the idle mixture, but shifts the range of the overall part throttle mixture by a significant amount either up or down

Steve,

Would you get a Porsche pre-muffler over switching to the SSI system or is this advise only for states where you have to have the stock exhaust on the car for inspection? I have the SSI system on now and could not imagine going back, except for the inspections.

My feelings were that nothing could beat a set of SSI and a good muffler!?

Joe

Thanks Steve, your wisdom is greatly appreciated! I've seen threads here previously on cat-bypasses vs. euro premufflers but cannot understand why the premuffler is considered better on an otherwise stock exhaust system. The premuffler creates slightly more backpressure I understand, but since I have the stock heat exchangers wouldn't less backpressure be better since the exhaust is already fighting the more restrictive heat exchangers? Or am I missing the point of heat exchanger upgrades entirely, which is quite possible.
Since I received my first speeding ticket today (80 in a 55, yep in VA this is reckless driving), I have a feeling that more self-control is probably what I need rather than more HP, but hey, its only money, points, and insurance right? :(

Your setup sound tres cool. Do you tune with a laptop? Where did you ever find all of the info you needed to interface, I figured all of the pinouts and data would be proprietary (I'm a computer programmer, this holds a lot of appeal to me)

Steve,

Have you ever thought of a new career!? You sure have done your homework and glad that you are a regular on Pelican!

Thanks for the insight!

Joe

So Steve, you made the DIY wideband O2 sensor? How hard was it?
thanks,
Chris

I was the guy selling that Euro brain. A guy came over to pick it up with his '84 USA targa. He tested it out and the one from his car was the same number so I guess either mine was a USA brain or the USA and Euro brains are the same number.

Hello

AFIR 08, 09, 11, 12, 13, 18 are the # for ROW Non catalyt versions.

Since 1984 the Porsches in germany could be ordered with US engine and since 1988 all Porsches came with US catalyt engines. in germany too

However some have low compression or are smoked via external airpump ( swiss )

A oversight is ,or should be, on Tobias Carrera 1 page www.netmotor.de

Porsche Boneyards in Germany ?

Freisinger, Tebernum, Braun, Kannacher.

used parts dealers in germany ?

Mittelmotor, Stöckel, FVD, Eiden, Eckert, Theimann, Albert

Grüsse

Thanks Roland, because of all of the replies on this thread, I have a much better picture of my car's motronic inner workings.