The 15 Y/O Turbo M42 Build Thread (Now Holley EFI Terminator X Controlled)

[Dj Buttchug]

Both the M20 flywheel and the M50 flywheel have 137 teeth. I verified this yesterday after removing the clutch and flywheel off the M42.

Here are some photos of why this doesn't work. You can see the starter bendix gear is not the correct size or pitch to fit into the flywheel ring gear. The bendix will just bounce off when the starter engages.


So my plan to run an m50 flywheel is out. After some digging and a conversation with ClutchMasters I have ordered a a new clutch and flywheel that SHOULD work.

M20 flywheel has seen better days. Clutch looks ok but the hotspots are not very satisfying to see. This clutch has 6k miles on it.

[varg]

That sucks, and is a real drawback to that system that is good to know about; it won't start if the battery gets low. Is the ratio of flywheel to starter tooth counts any different between M20 and M42? I don't think my M20 E30 cranks at under 200rpm but I've never paid it much attention because it's enough to start so

[Dj Buttchug]

Long over due update. Figured I should outline some of the process installing Terminator X LSX based hardware in the E30 chassis to run the M42B18 engine so if anyone tries to attempt this the thread may pop up in a google search.

The basics on the subject are what I have found to work/not work so far with the swap. Removing most of the engine wiring harness and installing the LSX harness is pretty straightforward. Obviously only using 4 injectors and 4 ignition coils the other half of the harness is neatly tucked away and nothing was cut. Pins were moved in the JB1 connector so the ecu will control the correct coils and injectors. Also not very difficult. All engine management sensors are now GM based. For my application a Holley sniper 2.5 bar map sensor was used. I found a GM coolant temp sensor with the correct thread pitch that will screw into the M42 head. The throttle position sensor on the M50 TB I am using is compatible with the ECU so nothing was changed there other than the wiring connector so it will clip into the Holley harness. No oil pressure, fuel pressure or knock sensors were used. Cam and crank sensors were made using Sieger Electronics cherry sensors. Overall the install was free of problems however it was very time consuming to install clean and to my liking. Budget 40 hours from start to finish just for the wiring harness install.

Now onto the problems. There is only one but it is a major one. The cranking speed of the engine is not fast enough to sync the cam and crank sensors on the 60-2 toothed harmonic balancer.

This may not happen on other installs but it did on my car. My engine has a lightweight M20 single mass flywheel. I installed this years ago because it was cost effective. Working through this problem I believe (and this is just a theory as of now) that the M20 flywheel could be a cause of a slower cranking speed due to the number of teeth on the ring. The starter bendix has a smaller pitched tooth gear as well. Cranking speed is 190 RPM with no spark plugs installed. With plugs in the engine it is probably 140-150 rpm.

Anyway, without sufficient cranking speed (over 200RPM at least) there is no fuel and no spark. The old MS1 system would catch it just fine. Never had any issues on the previous engine control stuff. So with that said, make sure to plan for this if you decide to go this route and update to a much newer management system. It is likely other brands will have this same issue if the cam and crank sensors used are digital.

As of now the engine cranks, all sensors are working. I am waiting for a WOSP high output starter motor on way from overseas to attempt to correct the issue. We will see how that favors. A possible flywheel change may be needed but I am not certain just yet.

[TobyB]

Also, I should add that during the install of the new standalone I was able to find the reason why the MS1 was turning off randomly. Turns out the main terminal connection at the front battery tray was the cause of the issues. The + connection was dropping out causing the car to suddenly shut off. My assumptions about the MS1 board were wrong. Too late to go back now.

I feel that pain-
a few years ago, I stripped apart the power supply for a very low- volume early automated audio console.
The thing was waaay ahead of its time in 1992, but had been flakey since its initial installation, and was scrapped sometime around 2007.

When I took the power supply apart, I found that one of the main ground busses had never been soldered, and there was evidence
of arcing in more than a few places. 2 minutes of soldering missed, 15 years of intermittent failures that couldn't be duplicated.

I now triple- check my own work, and then run a 150% current test looking for voltage drops....

t
which is why as you age, you work faster by working slower, I guess.

[Dj Buttchug]

Hello again, been a while. Now I got an M42 turbo setup of my own going. As of right now I don't have a good tune going though. Was wondering if DJ Buttchug or someone else had a good starter tune for MS2 to share. I cannot find a tuner locally and in some parts of the tune like the ignition table I am quite unsure what to do. So I need something safe i could run for this winter. Thanks! Any ignition, afr, VE tables or any other information very welcome. Even info about the general engine setup. Im running a 3.0mm MLS head gasket, arp headbolts, 0.5mm ring gaps and a large chinese turbo. Stock injector/fueling setup. Running planning on running 7psi for the next few months.

PM me a good email and I can send you a few things to get you started.

[baltic_wh4le]

Hello again, been a while. Now I got an M42 turbo setup of my own going. As of right now I don't have a good tune going though. Was wondering if DJ Buttchug or someone else had a good starter tune for MS2 to share. I cannot find a tuner locally and in some parts of the tune like the ignition table I am quite unsure what to do. So I need something safe i could run for this winter. Thanks! Any ignition, afr, VE tables or any other information very welcome. Even info about the general engine setup. Im running a 3.0mm MLS head gasket, arp headbolts, 0.5mm ring gaps and a large chinese turbo. Stock injector/fueling setup. Running planning on running 7psi for the next few months.

[Dj Buttchug]

Still working. Waiting on LSX coils and wires. New map sensor on way.

New routing for crank sensor harness


Constructed small heat shield to keep wash bottle from melting.


All wiring done except for these connectors. Bout time to get out the laptop and check our signals.

[Dj Buttchug]

Also, I should add that during the install of the new standalone I was able to find the reason why the MS1 was turning off randomly. Turns out the main terminal connection at the front battery tray was the cause of the issues. The + connection was dropping out causing the car to suddenly shut off. My assumptions about the MS1 board were wrong. Too late to go back now.

I will sell the MS1 with my current loaded tune (uses 440cc Bosch green giants) for the cost of shipping anywhere in the US.

Let me know if you're interested.

[Dj Buttchug]

Here is the Can network part of the harness. I was able to keep to stock boot for the install.

The Factory M42 DME and the Mega squirt grounded the main and fuel pump relays when the ignition was cycled on. With the Terminator X you can do this but you must use one of the input/output channels. Instead I opted to ground the ECU and the fuel pump manually. The two switches on the center console control the DME startup and fuel pump now.


And finally after a shit ton of wiring, going cross-eyed looking at flow charts the new DME is alive.

[Northern]

I'm sure I could google this, but any chance the m3 battery cover still fits with the ix washer bottle?
One of the many things I still haven't figured out a good solution for lol.

[Dj Buttchug]

Final fitment of the harness going in. Trying to retain the OEM harness cover. IX wash bottle I had laying around. Nice to have washers again.

[Dj Buttchug]

^ Very true.



Moving onto the crank and cam sensor issues. M42 runs mag sensors which kind of suck imo. Terminator X is better fitted with Hal Effect style so we order 2 proximity sensors.

After about 3 hours, some ACE harward bushings and a 4inch ABS plastic sheet I was able to create my own sensors for about $30 each. Crazy less expensive that OEM.

Here are a few photos of the final product. Cam and crank sensor have the same hold tab. I was able to trace out the mount tab and shape new ones out of the ABS





Fitment is good. Here is what they look like installed. We are running the exact same distance away from toothed wheels as OEM.

[Northern]

It's always so satisfying to see all the crap you can pull out of the harness when you know exactly what you need or not.

The harness on my silver car is in good shape but there's a bunch of useless wiring, ADS port, etc.

I pulled almost a whole grocery bag of wiring out of my shitbox's M52 harness once I understood wiring I actually needed, and realized how to depin the DME connector.

[Dj Buttchug]

Took a break from wiring and made a barrier for the intake.



Also city light retro wired up finally after 6+ years of having the option but never doing it.

[Dj Buttchug]

Engine wiring harness is now separated from the main and fuel pump relays along with the starter and alternator wiring harness. Several pins removed from the C101 and diagnostic connector. A mess of wires to be cleaned up. I have isolated the oil pressure, tach signal, coolant temp, and vehicle speed so the stock cluster will work as designed. The process is time consuming but not hard if you can follow a flow chart.


Here you can see we remove the o2 sensor relay. Main and fuel pump relay retained. This is the remains of the M42 harness. None of this will be used.




The engine cranks.



Waiting on cam and crank sensors from Sieger Electronics.