When I was running the engine on the stand, I used the default tables and only modified a handful of settings specifically to the engine. It started and ran "fine" that way. Once I moved everything into the vehicle and was ready to actually start tuning, I wanted to establish a more rational baseline to work from. The very first thing I did was upgrade my MegaSquirt firmware to the latest version. Mine was very old (3.1.0 vs. 3.4.2), and this change alone made the engine run noticeably better. I then made changes to the settings and tables following the approach of Andy Whittle on YouTube. Lastly, and this made the greatest improvement, I generated a new initial ignition table.
You can watch Andy's initial setup how-to video here. In just 11 minutes he walks you through the key initial settings that are specific to your engine and sensors. Since I am not running boost, his instructions on how to change the scales of the MS tables to give greater resolution for N/A builds was a nice insight. If you've done a MegaSquirt build before, there is really nothing new here, but for us first-timers, it's a concise, helpful walk-through.
For an initial ignition table, this tool is really handy. The table it generated with M10 specific information was radically different from the default table and dramatically improved running and driving. In the image below you can see the data for the M10 typed into the tool. Your idle vacuum may vary. If you don't have a vacuum gauge, you can calculated the idle vacuum from the MS MAP reading like this: Your in-Hg of vacuum at idle = 0.346 * (100 - your kpa of MAP at idle).
I made one more change after driving around for a bit, which was to turn Overrun Fuel Cut-off on with a delay of 0.5 seconds. This eliminated deceleration backfiring, which was really intense since I was driving with no exhaust system.
I hope this has been helpful.
So, my first specific task towards converting my M10 over to EFI was to draw up a wiring diagram for my MegaSquirt-based (more specifically, MicroSquirt v2.2 based) Stratified PNP ECU:
I will update this image as I continue to refine the diagram (updated 5/22/18 to correct coil wiring). There are few enough wires involved that I can use just the big 26-pin plug going into the OEM-style connector on the ECU.
I'm using the TPS from a 1984-89 Nissan 300ZX with the adapter from 02again that allows that TPS to screw right onto the BMW throttle body:
It may seem unnecessary, but I made a fancy fuel pump delete plate:
This is my first-ever attempt at sand-casting aluminum. I have wanted to get into sand casting for some time, and for this project in particular I want to cast a low-profile distributor delete cover. So, I started off with this much more simple fuel pump delete, using a wood-and-cardboard master, Petrobond casting sand and some scrap aluminum I got from Clint Eastwood.
That's it for now.
As I suspected, the Geo Metro air control valve did not move enough air for the m10 engine. So, I got a Ford style valve and installed it. Now the engine starts and idles as it should. Here are the details of my installation.
1. I made this steel bracket to mount the IAC under the first and second tubes of the intake. You'll note that I had to grind that nubbin down a little to clear the valve body:
2. Here is the Ford idle control valve mounted to the bracket. I have this thin wall tube that has an outer diameter that is exactly 16mm. I slid short lengths of it into the ports of the IAC and fixed them with Loctite 680 retaining compound:
3. I found a hose at the auto parts store, Gates #19047, that I was able to cut up to connect the valve and the inlet on the intake. Here is the lower section:
4. I made a flange from 1/4" aluminum plate with a bored hole and another length of that 16mm O.D. tube press fit into it:
5. Here is a shot of the upper hose. It is connected to the lower hose via yet another short length of the 16mm O.D. steel tubing:
This valve moves a lot of air, so the PWM duty cycle values for both start and idle are rather low.
That's it for this installment. There's not really anything left to do other than tune.
So, this project has been on hold for a while as my next big step is to really learn how to properly tune MegaSquirt, and I just haven't had the time to commit to that.
But, I had a couple hours today which I spent casting a proper delete plate for my distributor. This is my first sand casting using a core (to create the hollow for the cam end).
You'll see there's a little divot at the upper left. This is where I can drill and tap for the oil pressure sender, although I may end up moving that over to the oil filter housing.
That's it for now.
So, I've been busy selling off some of my cars, and haven't really been giving this project as much time as I'd like. But, I managed to finish the wiring harness and start the engine this week. I've updated the wiring diagram in the first post to reflect the current configuration. After the successful start, I'm taking some time to reconfigure my engine stand set-up so that it will be less ad hoc during the tuning phase.
Here is an overview shot of the engine as it sits this evening:
I ended up going with pencil coils on plug from a 2003-04 Honda CBR600RR motorcycle. I used a Bosch 0 227 100 211 igniter from a late '90s / early 2000s Volkwagon to fire the coils based on logic-level waste-spark signals from the MicroSquirt board. They are so low-profile:
For injectors, I used 19#/hr units that are much cheaper when you buy the rebuilt "Ford" versions on eBay (p/n 0280150943). I discovered that you can't re-pin the OEM AMP connectors in the BMW harness, so I bought new AMP Junior Timer Power connectors and terminals from Mouser for both the injectors and the ECU temperature sender:
Here is the PWM-driven idle air control valve, from a Geo Metro / Suzuki Swift 1.0L engine, mounted to a boss under the intake manifold. I am honestly not sure if it's working. The open-pipe first run was very loud and necessarily brief as I have no radiator installed. it remains to be seen whether this can move enough air to control the idle:
Here you can see the throttle body, TPS with adapter from 02again, and GM air temperature sensor (next to the dip stick):
I had the wiring tidy for the start, but then jumbled it in moving the engine around the shop this morning. I need to create a little panel/console to mount everything to so that everything remains orderly:
That's the news for now. The first start was so easily achieved, but the real work is really in this next phase of tuning. Especially given that while I am experienced with building wiring harnesses, I know next to nothing about tuning MegaSquirt.
So, this week I found time to finish machining my 36-1 teeth into the stock pulley and cast two more pieces for the EFI conversion.
First is a bracket to hold the crank sensor from DIY AutoTune:
Second is a small plate with a port to connect to a Suzuki Swift IAC (idle air control) valve. I'm not 100% sure that this IAC will allow enough air flow for the M10, considering it's from an engine with half the volume, but I had one easily at hand, so I'm giving it a try. I'm going to mount it to the underside of the intake using two pre-existing bosses and a custom bracket.
There are two smaller ports underneath my IAC inlet plate. One goes to the fuel pressure regulator, and the other I will use to provide a MAP reading to the ECU.
These two cast pieces really could be a lot more attractive and look more like "car parts" but right now I'm going for functionality and ease of production. It's amazing how quickly you can turn a piece of scrap aluminum into a usable part. The IAC plate took just 90 minutes from start to finish.
I think my next step will be building the wiring harness, which will probably take a while because I will be ordering new connectors and pins to make it from scratch... I don't like splices.
I've decided to share my process of converting my M10 engine over to MegaSquirt EFI. There are several build thread here and elsewhere that chronicle this process, but I'll be doing a few things differently, and I find that it's helpful to be able to see these sorts of projects from a variety of approaches. I will attempt to be as thorough as possible, including process, part numbers and prices. But, for now here's some random initial progress.
Here's my engine on the stand, largely stripped down.
The general scheme is tried and true method of slapping an intake from a 318i onto the 2002 engine and making it work. I have the intake and throttle body from a junkyard car, along with the necessary 318i water temperature sensor housing. I did not get the water return hard line that runs along the block under the intake, because my cooling system will not be stock. I will be using an electric water pump, among other changes.
I also have a largely pre-assembled MS-2 ecu from Stratified. This is a generic plug-and-play unit that they no longer sell. I bought it back in 2015, and it was insanely cheap for a pre-assembled unit. I liked the form factor (the stock MS boxes are so gross) and the OEM-style harness plug in the back.
These days, DIY AutoTune offers a very similar package they call the DIY PnP. I would highly recommend this approach if you care what your ECU box and plug look like.
Today, I made a flywheel holder and removed the front crank pulley. This pulley is odd to me. It carries three belts, none of which line up with my water pump pulley.
But, I'm not using the water pump, and the pulley has a nice fat, flat back face that I am currently machining my 36-1 trigger wheel teeth into.
That's it for today.