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Old 11-10-2017, 02:11 PM   #1
Broke4speed
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Default Tuning the M1.8 ecu (pre-95 960), an experiment.

I'm a decade or so too late, and maybe someone's already done it, but I can't find any of their work...so I'm going to post my own. I like deciphering early Bosch ecus, and when a 94 960 popped up in one of my local yards, a swap project was born. I plan to wire it up using the stock ecu and tcu (minus the torque reduction wires), and flesh out the file with an Ostrich emulator. There will be no boost, but I don't see why there couldn't be, once I'm more familiar with everything.

I've put some of my XDFs up on the tunerpro website (M2.9, OBD1 VW ABA, and VW Digifant 1 G60), so I'll be sharing everything I learn. Whether or not anyone uses it doesn't matter, I just like doing this .


The first thing I've discovered is that if you can find a copy of "Motronic Suite" (when you do, run it in admin mode), there will be M1.8 (pre-95) bins, and the software can convert the hex into maps already. It can only describe a few of them, but the raw data is all there. It looks a bit like BMW M1.7, which has part-throttle/idle mapping and separate 1x16 WOT maps for both fuel and ignition. With the realtime emulation function of the Ostrich, it's easy to trace the maps while running, so I'm currently transcribing everything over to Tunerpro to make an XDF.

I've pulled the bin out of the ecu I got at the junkyard (and the entire engine...but that's not the focus yet), and am using it as my base, but the other bins I've found are very similar. Just a bit of an offset between files, so the same xdf will work with adjustments. When I have a bit more of the transcribing done, I'll post up what I've got. I'm hoping to stumble upon the checksum info somehwere, so if anyone has any tips, it would be much appreciated. Too bad there aren't any ebay 'tuner' chips, they're always good for comparing and reverse engineering .
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Old 11-12-2017, 07:00 PM   #2
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Hmm...can't find any concrete info on the checksum, but I did find a document that describes how M1.8 works (although if you can't read french, it doesn't help much, lol). It does describe the various limp modes though, and it doesn't look like a missing speed signal is a terrible thing. I'm still trying to figure out a way to get the computer what it needs, but since I'm not running a 960 speedo, the speed signal might not be available. I can fake a 12v square wave pretty easily though, if need be.

http://en.calameo.com/books/0028413558bc9ef8a7643
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Old 11-12-2017, 07:46 PM   #3
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Contact LookforJoe > http://forums.turbobricks.com/member.php?u=25552
check out his thread, he used LH2.2 in his '87 X1/9 & get rid of the L-Jet. And seems to be a master of ecu tinkering. Or try contacting Sabbs, Or the Lostartof, or Fredsems
http://forums.turbobricks.com/showthread.php?t=287824
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Old 11-17-2017, 10:42 AM   #4
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One of the things that's been bugging me has been the whole 'speed sensor' nonsense, and whether or not it's a critical component of M1.8 or not. I can say for certain that it isn't on the later M2.9 I've worked with, but it's never a good idea to overlook a sensor input...just in case. Luckily, there is a bit of info out there about what type of pulse the ecu needs, so I can work with that.

The 48-window wheel in the diff sends a pulse to the 960 speedo, and it splits it off. A 48-pulse signal goes to the ABS, and a 'fabricated' 12-pulse signal goes to the ECU (possibly TCU as well, but not clear yet). The raw VR signal from the diff is conditioned by the speedo to look more like a square wave, from what I understand. I don't want to go through the hassle of mounting the 960 speedo as a standalone unit just to get the signal I need, and I already have a nice GPS speedometer, so I started looking in to how to get a proper pulse. I found this from 2010 on a Haltech forum:

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Greetings all, i felt like posting this to give people a little bit of insight on the calibration of their speed sensor inputs. All it takes is a little math.

To determine the number of pulses per km the ECU requires in the speed sensor calibration field, we first need the number of teeth that our trigger wheel, transmission, wheel hub teeth, etc., has. For this example, we'll keep things simple, we'll pretend we've got a wheel sensor with 8 teeth around it.

We also need to determine the circumference of our tire, in order to know how many pulses per km the sensor will read. So, on this example, lets make it a 27" tire diameter.

Our formula for calculating the pulses per km can be summed up like this:

P/Km = 1000 (meters in 1km) / [ (pi * diameter) / # of teeth on sensor ]

So, in this example with our 27" tire we must convert 27" to meters to keep things in the same unit system (metric), so multiply inches by .0254 to get meters.

P/Km = 1000m / [ (3.1415 * .6858m) / 8 ]
P/Km = 1000 / 0.2693
P/Km = 3713 <<<< This is the number you will put in your pulses per km field in the Calibration tab for the vehicle speed sensor.
So, my rolling diameter is 24.9", and I'm looking for a 12-tooth signal. The math works out to 3765 ppm (taking into account the difference between KM and miles)...which is close enough to 4000 ppm that I could actually get away with using a cheap GPS-to-pulse signal converter. It should be close enough to keep the ECU from freaking out. If anything, the speed cut may kick in sooner than it should, but I highly doubt I'll ever go fast enough to trigger it anyway.
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