M42 ECU Conversion: Link G4X/E36X

[bmwman91]

I am going to document my ECU conversion as it progresses over the next few months and share as much info as possible.

First, which ECU am I going to be running? It is the BMWLink E36X, which is a Motronic form-factor version of Link's G4X XtremeX product. The G4X line was released around the beginning of 2019 and is their current latest-and-greatest platform. The XtremeX is the 2nd highest-tier ECU in that line. As far as "enthusiast" grade ECUs go, it is one of the better ones out there spec-wise, with AEM Infinity products being IMO the main competitor (not that it matters...Motronic has an 8 bit MCU running at 1MHz...basically everything on the market now runs 100-200MHz and on 16 or 32 bit cores).
E36X ECU: https://dealers.linkecu.com/E36X_2
G4X XtremeX specs: http://linkecu.com/documentation/XtremeXPlugInECUSpecs.pdf

These seem to retail for $1000-1100 at US dealers. That is VERY affordable for a quality aftermarket ECU. It is still what I'd consider an enthusiast-grade ECU, although plenty of racers use Link. "Real" motorsport-grade ones usually start at $4000 as a bare minimum, and have a ton of features that I have no need for (the M42 is a very simple engine compared to modern performance engines). Even better, it uses the same 88 pin connector as the M42's Motronic 1.7 ECU, so I really just need to move some terminals around and add new wires for the features I will add. It was a close call between this and the AEM Infinity 506, but the AEM ECU had a top-entry connector that I disliked since it would not work well with the factory ECU mount location, and it would require me to either use external ignition coil drivers, or change over to newer ones with built-in drivers (which would have been fine, but a bit more wiring work). I only recently became aware of the E36X, and it checked all of the boxes I cared about. For the M20 folks out there, the 88 pin connector used by M1.7 can be bought new at a number of places (quite a few motorsport ECUs use it as it turns out), and it uses the same terminals as the 55 pin connector on M1.3, so you could actually swap it right onto your harness if you get the terminal extraction tools.

Regarding connectors and terminals, I will try to keep this post updated with part numbers as I accumulate them. Nearly every connector on our wire harnesses is a commercially available part from TE/Amphenol, from their various "Timer" series. The Motronic connectors use Micro Timer 1 and Junior Power Timer terminals, almost the entire rest of the harness uses Junior Power Timer terminals and housings, and (at least on the M42) the ignition coil connectors use Standard Power Timer terminals. You'll note that the technical drawings/datasheets for these have a zillion different variants. Most are unavailable, and the ones below were among the few that were both the correct type and still available on the web. This applies to all of the terminals listed below. BMW also has PNs for all of them, but they also mark them up heinously, so I only list those when it's the only option.

COMMON TERMINALS / CONTACTS
Micro Timer 1 female terminals: TE PN 929952-1 (for 0.5-1.0mm^2 wires)
So far this is the only problematic one...it is very likely out of production, and there is only one place that I have found which still stocks them. Micro Timer 2 & 3 terminals won't work in the Motronic connector as far as I can tell. I bought way more than I needed so as to have spares, and I got them here:
https://www.onlinecomponents.com/te-connectivity-amp-brand/9299521-10530804.html
I have also seen PN 929927-1, which takes 0.2-0.5mm^2 wires, available at a few places in the UK.

Junior Power Timer female terminals: TE PN 927771-3 (for 0.5-1.0mm^2 wires), 927768-3 (for 1.0-2.5mm^2 wires)
Used on the larger Motronic connector terminals, and nearly everywhere else in the harness where a rectangular housing is found.

Standard Power Timer female terminals: TE PN 927831-2 (for 0.5-1.0mm^2 wires), 927837-2 (for 1.0-2.5mm^2 wires)
These are used on the M42's ignition coils, as well as in the relay sockets up on the firewall.

2.5mm round male terminals: TE PN 929963-1 (for 0.5-1.0mm^2 wires), 929964-1 (for 1.0-2.5mm^2 wires)
Used in many of the same places listed for the female terminals below.

2.5mm round female terminals: TE PN 929970-1 (for 0.5-1.0mm^2 wires), 929971-1 (for 1.0-2.5mm^2 wires)
At least on the M42, these are used in the AFM connector and O2 sensor connector, C101, diagnostic plug, as well as in various places in the chassis wiring.

COMMON CONNECTOR HOUSINGS
2 position compact receptacle, Junior Power Timer (JPT): TE PN 1-825414-5
Used on the M42's fuel injector sub-harness. There is another PN, 826008-5, which looks similar but will not work on the injectors. It lacks the cut-out needed to clear the injector body, so don't buy that one.

2 position receptacle, JPT: TE PN 827551-3
This one is on the ICV, oil pressure switch, temperature gauge sender and some other places.

3 position receptacle: TE PN 1-827578-1
This is found on the M42 TPS, the M20 ICV, and a few other places.

7 position round connector housing. The TE parts are not available, but BMW parts dealers seem to have them.
Male housing: BMW PN 12521718125
Female housing: BMW PN 12521718126
Female housing lock ring for panel-mounting: BMW PN 12521718127
90deg rubber boot: BMW PN 12521737944
The male & female housings are used on the M42's AFM connector, and on the M20's fuel injector harness connector. I can't find the PN for the straight boot at the moment.

Other JPT connectors: Search around online for Junior Power Timer connectors and you'll see a bunch of the other ones with 2-7 positions. There are really too many to list here since, at least for this project, I don't need them all.

88 pin "Motronic" connector, with a few places that I found it for sale. Not cheap, and you could probably find a hacked-off one on eBay for a lot less (just de-pin it and you are good to go). M42 owners don't really need to worry about this since we already have one!
https://prowireusa.com/p-2487-88-way-bosch-connector-kit.aspx
https://www.automotiveconnectors.com/88-way-boch-ecu-connector-housing-assembly.html
https://www.msel.co.nz/epages/motorsportelectronics.sf/en_US/?ObjectPath=/Shops/motorsportelectronics/Products/CONAMP88K
https://racecal.co.uk/products/bosch-88-way-connector-terminals
A catalog for the 88-pin series of plugs: https://www.dalroad.com/wp-content/uploads/2015/05/88way-plug-in-connection.pdf


To crimp the terminals, you will want to get some decent crimpers. There are generic ones out there that work reasonably well, although they don't make the crimps as nicely as the factory did. Although I use different ones, these look like cheap ones that would work well with all of the terminals above:
https://www.amazon.com/IWISS-Barrel-Terminal-Crimper-Terminals/dp/B07476C1LD/
Personally, ratcheting ones are a lot more pleasant to use and this looks like a decent cheap setup:
https://www.amazon.com/IWISS-Ratcheting-Crimping-Tool-Non-Insulated/dp/B08DRCRRCQ/

For terminal extraction, this is the kit that I have. It has many more than are needed for this connector system, but I have lots of projects so it's fine for me. There are a bunch of cheaper copycat kits of this out there now, and they are all just as good. Don't buy any of the really cheap sets that look like a bunch of keys on a ring...they are not going to work well at all.
https://www.amazon.com/Performance-Tool-W89732-Terminal-Release/dp/B00EDEEICA/


I am working out the initial plans for the wiring harness modifications, and it is all still pretty rough since Link tech support needs to get back to me on a couple of questions, and I need to decide which new features actually matter enough to add. I'll post up a big table of the stock & new pinouts for things when I finalize it in the next week or two. Additionally, some of you may recall the big full-color complete M42 wire harness drawing I made a while back. I'll be making another one of those to fully document the new and improved one.

To finish, as if there is not enough to read already, here is the list of "improvements" I plan to incorporate with this ECU:
1) Dual knock sensing. The M42 block already has 2 threaded bosses for knock sensors which were added in the E36, so I just need to buy them and bolt them on (plus add wiring).
2) Full sequential injection. Motronic 1.3 & 1.7 were set up to fire the injectors in two groups. I will be adding the necessary wiring to fire all of them individually.
3) MAP-based load measurement. No more AFM (or in my case, MAF).
4) Closed loop feedback using a wide-band O2 sensor.
5) Traction control, or at least limited traction control. I can pull wheel speed signals from the ABS unit, and the ECU can do some limited torque management without an electronic throttle. Call E-throttle 5b...I may look into some variant of this if I have enough IO's left.
6) M50 ICV. This should lead to a nicer idle than the M42's very basic PWM valve.
7) Logging oil pressure & temperature, fuel pressure & exhaust gas temperature (all 4 cylinders individually, using an external TC DAQ via CAN).

That's it for now. I'm going to take a break from thinking about this and go relax for the rest of the evening!

[bmwman91]

Here's an update for today, since I had a chance to do some poking around with the wheel speed signal sensors and a $20 eBay ABS computer. It turns out that bench-testing these things is not simple. They have extensive fault detection routines that run at start-up, and in the event of a fault they will basically not power themselves up enough to do any sort of meaningful testing. I'd have to connect some dummy relays and resistors to mimic the ABS pump. So, other than that I just used this thing to trace out the input circuitry for the wheel speed sensors and make sure that nothing there might get upset if I tapped into the signal lines externally.




I did pull the cover off of the one in the car and probed it with the rear wheels lifted and the engine idling in gear. The 16 pin DIP IC in the middle is the signal "conditioner" that takes the VR sensor signal and turns it into a 5V TTL signal. The 3rd pin in from each corner is the TTL output, with the 4 corner pins themselves taking in the VR sensor signal. The simplest solution for my ECU project would be to tap into those TTL signals, but I have no desire to go mucking around with the ABS computer. While the chances of causing it to malfunction are small, I don't want to chance it.

So, the way I plan to go is with some MAX9926 chips. I had this little board from a data logger I had installed in a spare Motronic, which has a MAX9926 on it. I soldered some new wires onto it and tapped into the ABS computer connector (shoved stripped wire ends into terminal slots).






The connector itself is very easy to work with, and popping the terminals out / replacing them with double-wires later will be nice and easy I think.




I got the oscilloscope on the two rear wheels' sensor signals, plus the output of the MAX9926, to verify that I would get a clean TTL signal, and that the introduction of the MAX9926 was not causing any sort of issue or change in the VR sensor signal that the ABS computer also relied on. Here is what it looks like in first gear at idle. Yellow is the right-rear wheel, and green is the left-rear which also had the MAX9926 tapped into it.




Here's ~10MPH...




And ~45MPH...




The other thing I was curious about was any voltage difference between the ECU ground (on the battery tray) and the ABS computer ground (up under the dash). The multimeter showed a negligible difference with RMS averaging.




The oscilloscope showed significant, but extremely brief, transient spikes. This is from the ignition, and the peak value was influenced by how I routed the wire from the ECU ground over to the ABS computer. So, at least some of this is driven by EMI in the long extension wire. Anyway, this is ~1-20MHz noise, which should be a non-issue with any reasonable amount of bypass capacitance installed in the VR conditioner circuit I'll make.




Other than that, I received the E36X today. It is a nice little unit with full conformal coating all over (looks like they dipped the 2 boards separately before assembling them, while being careful not to get it in the connectors). The large ignition coil driver ICs are placed intelligently near pin 55, which is the dedicated ignition ground connection. This thing is intended to run an M50, so any M20 folks here who want to go full COP could definitely use this thing. A big part of this thing's appeal is the fact that it'll drive the coils directly, negating the need for a "smart coil" conversion or any sort of external coil driver module.




Part of me was tempted to plan to void the warranty and solder wires between all of the "extra" connections and the unused pins on the Motronic connector, but I need to make a hole in the ECU case to run the MAP line anyway, so I think I'll just leave well enough alone. Although...I could run an external MAP sensor and connect its output to a spare analog input so that everything is routed through a single main loom...must resist the urge to immediately hack-up my new toy.






Other than that, I got out some of my spare Motronic bits and did a quick bench test to ensure that it was functioning and talking to my computer.




That's it for today. There will be plenty more TMI updates as I continue to work on this!

[keflaman]

I'm amazed at what you can do and your knowledge of all this (to me) voo doo.

[Warsteiner]

That's awesome!!!  Keep up the great work!

Cheers,
~Ralph

[bmwman91]

Thanks guys, hopefully this will be an informative thread for folks. I have a parallel copy going on over at r3v too.

So I played around a bit more with the oscilloscope and MAX9926 board today. This time I connected it to the wheel speed sensor inputs, but ran the engine with the wheels stopped. I'll need to work a bit on some filtering and changing threshold voltages since I was getting a good amount of ignition-driven false triggers. The MAX9926 is pretty configurable, and the little board I bought is by default set up to (basically) run at maximum sensitivity. It can be configured to have a higher minimum threshold before it'll trigger, and the input can be low-pass filtered to reject stuff like the ~10MHz ignition noise pulses.

Here's a false trigger with everything grounded at the ABS computer. Blocks of these pulses were occurring at ~30Hz at idle, which coincides with 900RPM, so it is most likely a product of the ignition system. Fuel injectors could also be making some noise since they produce ~80V flyback spikes when they close, which are clamped by the driver ICs in the ECU and dumped to ground. ignore the cursor measurements, I forgot to turn them off.




I captured a bunch of these, and while many had spikes from the ignition, some were triggered by ~200mV drift in the wheel speed sensor voltage (the MAX9926 is VERY sensitive when set up to be). Based on my signal captures, the wheel speed sensors put out ~2Vp-p with the car idling in first gear, which is SLOW, so I could probably set 1.5V as a minimum threshold and be good.

Here is what it looks like with the oscilloscope grounded at the ECU, and the MAX9926 still connected over at the ABS computer. Basically, this is what the ECU would "see" coming from it, although I suspect that some of the extra noise spikes are EMI being picked up by the 4ft ground wire I ran from the ECU ground point to the driver's footwell. Everything starts acting like an antenna to some degree.




Here's that big noise spike, zoomed in. Again, this is mainly >10MHz noise here, and based on measurements with the wheels moving I think that the wheel speed signal will be ~1600Hz at like 150MPH, so I can definitely put some low pass filtering on the MAX9926 input.




Other than that, it's back to work tomorrow and I think that the remainder of 2020 will be fairly busy for me. Progress on this may be slower than I like, but I will keep the updates coming.

[bmwman91]

I am basically done with the wheel speed signal investigation stuff today. I had some spare components laying around and redesigned the input to the MAX9926 so that it would much more effectively filter noise out. You may be wondering why I am starting out putting so much effort into setting up the signals for traction control, since it is probably the least necessary part of this project. Well, it's sort of the only part that is "new" to me in terms of the electrical stuff. Some of you may recall my Motronic reverse engineering thread, and my engine harness rebuild earlier this year...there's not much mystery there for me, so I am just tackling the thing I am least familiar with first.

Anyway, I swapped out the 1nF cap that this little board came with for an 8.2nF cap in my spare parts pile. That went on the positive input line after the 10K resistor. For the negative input line, I jumped it directly to ground (bypassed the 10K resistor) since the second wire of the wheel speed sensors is also grounded. If both were actually usable, this never would have been an issue to begin with since the MAX9926 works a hell of a lot better with differential signals, but oh well, the E30 is old and just designed that way. For the 4 channel board I will design for the permanent install, I will probably make the low pass filter even more aggressive since I only need it to work for an input of 2kHz (that's like 180MPH...which is a lot faster than the car can go).




After hacking together the changes I went back out, removed the knee bolster and shoved the wires into the rear of the ABS plug's terminals yet again. The result was ZERO false triggers with the car running. The ignition noise spikes were still there of course, but the disturbances they created were of too small an amplitude and too high a frequency to trigger the MAX9926. The noise still gets through a little, but not nearly enough that it would register as a logic-high state anywhere.
Yellow = MAX9926 output (no false triggers wanted here)
Green = Filtered input signal
Blue = Raw/pre-filter input signal
Note the voltage scales.




Zoomed in a bit more on the central spike.




I also lifted a wheel and played around to see how slow I could spin it and still trigger the MAX9926. It looks like ~6.7Hz, or ~0.6MPH. So...I think it is plenty sensitive.




Just for fun, here's a capture of me using my foot to give the wheel a big push and letting it coast to a stop again. I managed to get it going a whopping 7.4MPH! The Wavetrac diff did present a little bit of resistance to spinning one lifted wheel.




That's enough fooling around with this for now. At some point I will have more than oscilloscope shots to share lol. Well, it'll probably be Excel tables of wiring diagram pinouts and drawings of the harness before photos of anything actually interesting show up lol. Madness? This is NERD OCD!

[apexspeedtech.com]

I'm glad to have ran into this thread,   I joined this forum yesterday, and I happen to be a motorsports electronics engineer.... and a Link dealer... and am converting my 318ti M44 to a standalone ECU in the next few weeks.

Comments on your thread:

1.  You can get all those Mini Timer (we call them Bosch LK's) connectors and components from milspecwiring.com or racespeconline.com.  Great resources for engine management system wiring supplies.

2.  Based on your posts, if you can somehow return that E36X link, I would.  Get yourself a Storm or Extreme instead, the hardware is the same but they have a lot more flexibility as they're not constrained to the BMW AMP connector on the ECU.  You can find the headers with flying leads, or even buy complete adapter harnesses, in plenty of places.  So its still plug & play, but more flexible.  This is what I'll be doing, with adapters for several different ECUs.

3.  When you're ready for knock sensing, get a Link KnockBlock or another knock audio amplifier with a 3.5mm audio out that you can connect to your computer. 

4.  Go fully sequential on fuel and I'd consider a coil on plug conversion to go fully sequential spark as well.  I've just received the plate and coils to convert my M44.

5.  Link has 2 fueling modes, "traditional" uses MAP as the primary load source; you may find the modeled fuel equation better.  This uses MAP as well but creates an air charge estimate and then determines fuel mass to inject.  It requires a bit more injector data but its ability to track the lambda target is excellent.

6.  For traction control, throttle-based torque reductions are about NVH and emissions compliance.  Torque reductions based on fuel reductions and ignition cuts are more incremental, responsive and effective.

7.  The M50 IAC is a good one, so good in fact I use it everywhere.  I have twin M50 IACs on 1400hp turbocharged offshore powerboat V8s.  I used a pair on a Lamborghini LM002.  We used them for active engine braking control on Suzuki Superbikes.  Its the Swiss-army knife of air control valves.

8.  I highly recommend adding a fuel pressure sensor from the beginning.  It is the most common, #1 issue in engine management system installations, and doing it now will save you at very least an equivalent amount of time at some point later in your project.

10.  And NOW FOR THE WHEELSPEED SENSOR discussion.  Caveat #1:  I'm not an EE, I'm a calibrator with an old and worn out brain.  So please tolerate my muddling through the following:

All the Link ECU digital inputs are designed to read open collector 0-5V square waves.  They are not variable reluctance like the crank and cam.  They do have a software-selectable pull-up and you can define the edge.  Problem is that most ABS sensors are VR, and worse, they have a pretty low output at low speeds because of the tooth counts involved, as you saw from your testing.  I've used this unit:  https://www.milspecwiring.com/DMC-D-Converter-Wheel-Speed_p_528.html

I haven't had luck piggybacking ABS signals an ECU speeds with a mag/hall convertor, and I don't know anyone who has.  Standard practice is to get wheel speeds off of a CANBUS (which your ABS unit doesn't have) or to use an ABS unit that has open collector outputs.  2002 and later E46 ABS units are like this, and I know quite a few people who have retrofitted this to the E30 and E36 chassis with success.  Honestly, this is the best way for you to get traction control & upgrade your abs in one shot.  That said, it might be a fun experiment to see if you can share those signals between the stock ABS unit and get a reilable speed at the Link.

Feel free to ask any questions! As soon as I find a clean, complete DASC kit I'll be doing a standalone install myself.

Cheers,
Neel

[bmwman91]

I'm glad to have ran into this thread,   I joined this forum yesterday, and I happen to be a motorsports electronics engineer.... and a Link dealer... and am converting my 318ti M44 to a standalone ECU in the next few weeks.

Comments on your thread:

1.  You can get all those Mini Timer (we call them Bosch LK's) connectors and components from milspecwiring.com or racespeconline.com.  Great resources for engine management system wiring supplies.

2.  Based on your posts, if you can somehow return that E36X link, I would.  Get yourself a Storm or Extreme instead, the hardware is the same but they have a lot more flexibility as they're not constrained to the BMW AMP connector on the ECU.  You can find the headers with flying leads, or even buy complete adapter harnesses, in plenty of places.  So its still plug & play, but more flexible.  This is what I'll be doing, with adapters for several different ECUs.

3.  When you're ready for knock sensing, get a Link KnockBlock or another knock audio amplifier with a 3.5mm audio out that you can connect to your computer. 

4.  Go fully sequential on fuel and I'd consider a coil on plug conversion to go fully sequential spark as well.  I've just received the plate and coils to convert my M44.

5.  Link has 2 fueling modes, "traditional" uses MAP as the primary load source; you may find the modeled fuel equation better.  This uses MAP as well but creates an air charge estimate and then determines fuel mass to inject.  It requires a bit more injector data but its ability to track the lambda target is excellent.

6.  For traction control, throttle-based torque reductions are about NVH and emissions compliance.  Torque reductions based on fuel reductions and ignition cuts are more incremental, responsive and effective.

7.  The M50 IAC is a good one, so good in fact I use it everywhere.  I have twin M50 IACs on 1400hp turbocharged offshore powerboat V8s.  I used a pair on a Lamborghini LM002.  We used them for active engine braking control on Suzuki Superbikes.  Its the Swiss-army knife of air control valves.

8.  I highly recommend adding a fuel pressure sensor from the beginning.  It is the most common, #1 issue in engine management system installations, and doing it now will save you at very least an equivalent amount of time at some point later in your project.

10.  And NOW FOR THE WHEELSPEED SENSOR discussion.  Caveat #1:  I'm not an EE, I'm a calibrator with an old and worn out brain.  So please tolerate my muddling through the following:

All the Link ECU digital inputs are designed to read open collector 0-5V square waves.  They are not variable reluctance like the crank and cam.  They do have a software-selectable pull-up and you can define the edge.  Problem is that most ABS sensors are VR, and worse, they have a pretty low output at low speeds because of the tooth counts involved, as you saw from your testing.  I've used this unit:  https://www.milspecwiring.com/DMC-D-Converter-Wheel-Speed_p_528.html

I haven't had luck piggybacking ABS signals an ECU speeds with a mag/hall convertor, and I don't know anyone who has.  Standard practice is to get wheel speeds off of a CANBUS (which your ABS unit doesn't have) or to use an ABS unit that has open collector outputs.  2002 and later E46 ABS units are like this, and I know quite a few people who have retrofitted this to the E30 and E36 chassis with success.  Honestly, this is the best way for you to get traction control & upgrade your abs in one shot.  That said, it might be a fun experiment to see if you can share those signals between the stock ABS unit and get a reilable speed at the Link.

Feel free to ask any questions! As soon as I find a clean, complete DASC kit I'll be doing a standalone install myself.

Cheers,
Neel

Thanks for the detailed response, there's a lot of good feedback in there.

1. Good to know. I am always happy to find new sources for these things. Regarding wire harness materials, I will be able to keep together most of the existing wire in the stock harness, but will be replacing a few key conductors. Specifically, I am replacing the switched legs of the ignition coil primaries since the stock shielded wire setup is not up to "modern" standards...they stripped the shield back almost 5" where the wires go into the 88 pin plug, so the big EMI spikes from the inductive flyback on the primaries are unshielded where those wires are stuffed up against all the other signals. Obviously it works well enough, but I want to yank them and replace them, with shields terminated in the way specified in all of the newer BMW wiring diagrams ("shield extends up to <= 10mm from ends"). Right now, I have found very good pricing on shielded TEFZEL wire (MIL-DTL-27500/MIL-DTL-22759) at several aircraft wiring supply sites. I am 99% sure that I'll be going with "TG" series shielded TEFZEL wire for the new ignition lines since it is rated at 150degC and 600V, and has a braided copper shield which is probably even better than the lightly twisted shield in the stock wire. I'll be using 16ga (~1.5mm2) there. Since most places sell 100ft minimums, I am also going to use it for the switched legs for the injectors, ICV and evap purge valve (all the switched items). Necessary? No. But why not, if I have a spool of it. And at least for injectors & ignition, 16ga is a bit larger than the stock stuff anyway.

2. I am pretty locked-in to the E36X (which Link confirmed is an XtremeX main board mated to a Motronic-shaped carrier board that houses the IGBT coil drivers and whatnot). Since I am not all that concerned about the warranty, I do plan to solder jumper wires between various pins on the board-to-board header and the AMP connector, so that it all runs through one loom. I am also considering a remote MAP sensor so that I don't have to run a vacuum line from the ECU through the firewall. Anyway, I really want to maintain the stock form factor & connector. Emissions inspections don't involve looking at the ECU or anything, but the state of California is kind of crazy and I want to look as stock as possible if they ever decide to start looking there.

3. Good to know about knock calibration. I assume that getting it set up properly involves more than just plugging in the bore diameter and a windowing angle range? This is 100% new to me.

4. Yup, full sequential fuel is a requirement...no point in all this work if I don't take full advantage of it. Also, fun fact...I invented the M42/44 COP conversion, right here on M42Club back in ~2006. So, it is needless to say that I have already converted.

5. I plan to roll with the modeled fuel mode. Again...all this trouble for (likely) little power gain, so I am going to use every feature that I can. My plan is to machine an inline adapter that goes into the feed line to the fuel rail, and equip it with a Bosch PST-F1 (combined temperature & pressure sensor). I figure that I'll get a reasonably good read of pressure, and "close enough" on the temperature, with the sensor mounted ~12" from the rail. The other option would be to get a spare rail and try to mount it directly into there, but I don't know if that is necessary. Additionally, I plan to use the same sensor in place of the stock oil pressure switch so that I can monitor pressure & temperature, and have the ECU control the oil light in the instrument cluster. The only challenge is that the pressure switch hole is M12x1.5, and the sensor is M10x1, so to adapt the sensor it'll be offset out of the hole ~5mm by the adapter.

A tuner that I have worked with a lot recommended retaining the MAF sensor during tuning. Not that the ECU will use it, but using it as a source of additional telemetry (since the ECU does have spare ADC inputs) was suggested as a good way to start really getting a good feel for the VE/MAP readings as I tune stuff. Thoughts?

6. Good to know about TC methods...I'd like to not have to convert to E-throttle if possible. Programmable throttle curves seem fun, but it would be a tremendous amount of work.

7. Awesome to know that the M50 IAC is a solid performer. I have one on order.

8. See #5.

10. Regarding the wheel speed sensors, the custom board I design will basically be an actively driven TTL output setup. That is what the MAX9926 is all about. It is a chip designed specifically for interfacing with VR sensors and producing a TTL output. Personally, I don't like open collector arrangements in the car environment since the pull-up resistor makes for a high impedance signal line when the output is "off", and at least as far as I have seen so far, ignition EMI is not insignificant. So, I will be taking the MAX9926 open collector output and then buffering it with a fully active line driver, so that both high and low output states are actively driven / low impedance. As you can see above, the rough tests I did show that the MAX9926 will reliably pick up the wheel speed signal down to ~0.6MPH, which I assume is going to be fine. My interest in TC is much more about conditions when driving / cornering under high throttle, not so much to minimize wheel slip when accelerating from a stop. Besides, the ~200bhp I am making now combined with very sticky tires means that I can't do much spinning anyway lol. I will be happy to share what I do regarding VR signal adaptation since it looks like I have it all taken care of. The ABS computer does have its own IC that does a pretty good job of converting the VR sensor signals to TTL output, but I want to avoid hacking up the ABS computer at all since it is a critical safety system, and it also (basically) disables itself in the event of any fault condition, to the point that it drops the power rail to the VR signal conditioner IC. So, an external solution that directly reads the VR sensors seems like the way to go.

[apexspeedtech.com]

All good.  I'm in Southern California, smog's going to be an issue.  A circuit that will convert common ABS wheel speed sensor outputs to a 0-5V square wave without any effect of the operation of the ABS is something I wished I had multiple times.

[Warsteiner]

All great info here.

Welcome to the forum Neel !!  We can definitely trust what Neel brings to the table since I know of Neel and have heard only great things about him.

Neel... we have a mutual friend !!! Jimmy Pettinato. Neel did an amazing job with Jimmy's 2.3L S14. Jimmy is a really great friend of mine.

Welcome again!!

Cheers,
~Ralph

[apexspeedtech.com]

Ralph, thanks for the kind words.  Jimmy is a good friend and I look forward to when I can see him and his stable of E30's myself!

The funny thing is I am here as a "civilian."  Though I've been a tuner for 20 yerars, I've never tuned my own car.  So its time to put my money where my mouth is.  Guess I'll be taking my work home with me!

All great info here.

Welcome to the forum Neel !!  We can definitely trust what Neel brings to the table since I know of Neel and have heard only great things about him.

Neel... we have a mutual friend !!! Jimmy Pettinato. Neel did an amazing job with Jimmy's 2.3L S14. Jimmy is a really great friend of mine.

Welcome again!!

Cheers,
~Ralph

[bmwman91]

Ha, small world it seems! At least it is for lovers of old German cars.

Do you have a recommendation for a type or source for splices? I'd like to find a small/compact butt splice with heat shrink tubing for some areas of the harness where BMW used an existing splice but a lot of extra wire looped in (which I'd remove) for ease of assembly. For a case like where a bunch of wires join (like where most of the ECU ground all tie together with one larger conductor that goes to the ground lug, what's a good sleeve type to use?

[apexspeedtech.com]

Ha, small world it seems! At least it is for lovers of old German cars.

Yes it is, and one more thing:  Jimmy's car also runs a Link ECU, so there's another resources for this thread.

Do you have a recommendation for a type or source for splices? I'd like to find a small/compact butt splice with heat shrink tubing for some areas of the harness where BMW used an existing splice but a lot of extra wire looped in (which I'd remove) for ease of assembly. For a case like where a bunch of wires join (like where most of the ECU ground all tie together with one larger conductor that goes to the ground lug, what's a good sleeve type to use?

See here:

https://www.milspecwiring.com/search.asp?keyword=splice&search=GO

The more expensive Raychem ones come with shrink, the less expensive barrel splices you should cover with a piece of semi-rigid glue shrink:

https://www.milspecwiring.com/W5-Glueline_c_450.html

I don't find a need to use the Raychem species except where weight and compactness is the #1 priority; in practice I feel both work the same.

Cheers,
Neel

[bmwman91]

Thanks! "Parallel splice" is what I was looking for it seems.

Question...I have seen some places mention that MAP sensors (and oil pressure) should not be mounted on the engine itself as the vibrations will cause premature failure. Other places make no mention of this. What is your thought on it? In my case, I am running stock M42 hydraulic mounts, and I plan to continue to do so. The oil filter housing already has a perfect threaded boss for the Bosch PST-F1, and I am 99% sure that I am going to use a Bosch PST-1 mounted on the intake manifold plenum since that gets me MAP+IAT, and I don't have to mess with a vacuum line to the ECU. Also, it looks like the Bosch KS4 knock sensors are cheap and readily available, so I will be getting some of those too.

PST-1 data: https://www.bosch-motorsport.com/content/downloads/Raceparts/Resources/pdf/Data%20sheet_70513419_Pressure_Sensor_Combined_PST_1/PST_3.pdf
PST-F1 data: https://www.bosch-motorsport.com/content/downloads/Raceparts/Resources/pdf/Data%20Sheet_70496907_Pressure_Sensor_Combined_PST-F_1.pdf
KS4-P data: https://www.bosch-motorsport.com/content/downloads/Raceparts/Resources/pdf/Data%20sheet_69010059_Knock_Sensor_KS4-P.pdf

[apexspeedtech.com]

Question...I have seen some places mention that MAP sensors (and oil pressure) should not be mounted on the engine itself as the vibrations will cause premature failure. Other places make no mention of this. What is your thought on it?

Like so many things its on a spectrum, the answer is if you can remove mount the sensors you they will last longer.  The more high-frequency vibrations your motor has, the worse its going to be.  I've had customers direct mount them and they are fine.  We hard mounted them to some Rousch v8's in early Grand-Am days, they wouldn't last a race that way.

Bosch motorsports sensors are great, for your application just find their OEM application. 0261230030 1 bar TMAP is used on all sorts and will work great.
The PST-F1 is just a Mazda CX9 part.

That KS4 is super, super common.  Just google it.

I can't comment on whether the ones bought directly from Bosch Motorsports are in some way superior, but in my experience the OEM sourced ones have never failed me.  And its really, really hard to mess up something like a KS4.  If I was running a pro-racing team, I'd buy them from Bosch Motorsports for the peace of mind.  On my car?  I'd find the cheapest alternate supplier version - not to save money, just to see for myself if there's any difference in performance or longevity.