I am going to document my ECU conversion as it progresses over the next few months and share as much info as possible. While the M42-specific stuff won't be useful to all that many people since it's still sort of the red-headed step child of the E30 world, I think that a lot of the methodology, wiring harness design and connector part numbers will be of interest to people.
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/Xtr...InECUSpecs.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
I highly recommend using parallel splices for joining wires. It is the OEM method. These are the terminals I use, and the second link is to crimpers that would work well with them.
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-T...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!
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/Xtr...InECUSpecs.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-...-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.
- 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
90° 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...ector-kit.aspx
https://www.automotiveconnectors.com...-assembly.html
https://www.msel.co.nz/epages/motors...ucts/CONAMP88K
https://racecal.co.uk/products/bosch...ctor-terminals
A catalog for the 88-pin series of plugs: https://www.dalroad.com/wp-content/u...connection.pdf
I highly recommend using parallel splices for joining wires. It is the OEM method. These are the terminals I use, and the second link is to crimpers that would work well with them.
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-T...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!
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