'84 Eta Crank Trigger

[ForcedFirebird]

Look at a pic of an e30 rotor cap. It's not a little point like most. This makes it so the ECU has a large window to fire. You can add as much as 50°, but realistically an n/a m20 doesn't need any more than 25 or so at peak TQ.

[flumph]

That's pretty cool about the distributor rotor! Never would have even occurred to me.

I pulled off the E manifold today and bolted up the I parts. Took the chance to clean some stuff up while I was in there. Managed to do everything without a wobble socket, which was interesting. Took about 3 hours to do the whole swap, not knowing what I was doing. Probably could do it in 1 now that I know where everything is.

Notes to anyone who hasn't pulled a manifold off before:
I had to pull my fuel rail off to get it to clear the thermostat housing. Strategic use of a rag and unconventional application of a breaker bar makes this easy though. Also, you have to pop out the oil return tube to get the manifold off. Other than that, it's a breeze.

Kind of funny though, apparently my car has been running in open loop for the last year. I've been probing around the harness that I pulled out of the car, and I found that the O2 sensor heater relay control pin is disconnected from the ECU. My O2 sensor has been running without a heater this entire time. Also found that someone played some funny games with the injector wiring at some point. Unless I'm mistaken, it seems that the earlier Motronic 1.1 cars fire the injectors on the positive side, where the later 1.3 cars fire them with an open collector signal from the DME.

Tomorrow I'm going to start routing wires in the engine bay and crimping stuff together. Getting nervous!

[ForcedFirebird]

Kind of funny though, apparently my car has been running in open loop for the last year. I've been probing around the harness that I pulled out of the car, and I found that the O2 sensor heater relay control pin is disconnected from the ECU. My O2 sensor has been running without a heater this entire time. Also found that someone played some funny games with the injector wiring at some point. Unless I'm mistaken, it seems that the earlier Motronic 1.1 cars fire the injectors on the positive side, where the later 1.3 cars fire them with an open collector signal from the DME.

no, all MFGR's that I know of provide a fuse 12+ signal to the injectors and the ECU grounds them to fire. The e30 has 2 injector banks on the "i" stuff which is controlled by the #6 spark plug sensor (cylinder identification) to cause a semi-sequential condition. If you don't have the #6 wire sensor plugged in, the ECU reverts to full batch fire.

As far as the 02, the e30 treats open and closed loop a little different than what most are used to. Since the NB o2 is heated, the "closed loop" is more based on coolant and air temps than o2 heating, NOT like most single wire o2 sensor systems do (the e30 is a 4 wire NB o2). The biggest factor the 02 sensor has on the Motronic stuff is fuel trimming. Problem with that is every time the ECU looses it's B+ memory input, the ECU is reset and all fuel trim memory is lost. This is why a CEL is erased on an obd1 when the battery is disconnected, later obd2 stuff hols faults until cleared electronically.

EDIT: None of this really matters with MS as you can control the variables that cause open/closed loop situations.

[flumph]

So it finally stopped raining and I had some time to start crimping stuff together. I got the relay block to work on the bench while the storms passed over, and I took the time to probe around the Motronic 1.1 harness.

One thing that I noticed is that the starter solenoid connector runs directly to a pin on the connector on the side of the fuse box. This is a black and yellow wire, which is also represented as you'd expect in the wiring diagram available from BMW on the internet. I discovered today that this pin has battery voltage in the default key run position, not just in the start position. In this case, the starter solenoid would always be engaged, and this would initiate cranking in the run position, not the start position!

Am I missing something? It would be easy enough for me to mount a pushbutton for this, but obviously I want to use the key. The fuel pump wiring is the only other thing I really want to use from the existing wiring, and that works fine.

Does the starter solenoid have battery voltage on it in the run position? If so, how does the crank position differ from the run position? This is the only thing I can't figure out, even after looking at the wiring diagram.

Also, I chose to ground the Megasquirt to the intake manifold. My multimeter shows 0.0 ohms between the manifold and the chassis ground from the engine block beneath where the AFM was. There are 5 wires that I crimped into 3 ring terminals and threaded down onto a stud on the intake manifold. I know resistance can vary under high-current load, and I'm just wondering if this is a bad idea.

The main thing though: the starter solenoid engages and activates the starter as long as it has battery voltage on it, right? If so, why does the same pin on the existing harness have battery voltage on it in the Run position AND the Start position? How do I wire this??

Edit: I also bought an AEM wideband because of the things I read about trying to tune with a narrowband, and that Innovate controllers blow sensors after a month. It still stands that in the harness I pulled out of the car, one of the injectors was hard grounded. Considering that the DME fires the injectors on an open collector ground signal, that means that one of my injectors was operating at a 100% duty cycle, even when the engine wasn't running. This means that I was firing SUPER rich on just one cylinder, fouling the NB reading for the other 5 and making them run super lean. This explains the fuel cut I was getting at high RPM and the mysteriously rich idle that I always had, no matter how hard I was with the parts cannon.

[ForcedFirebird]

The late model wiring harness has two wires that go to the starter solenoid. One is the heavy black/yellow wire that goes to the 6mm stud, then there's a black/green (or black yellow) that goes to the k5 relay in the fuse box (4mm stud). This disables power windows/lights etc as you are cranking the car, so that wire is open during start and should be grounded in run. If your starter doesn't have the second lug (ie early starter with late harness), then you can ground that wire, just not a good idea to operate accessories while cranking.

[flumph]

Alright, this is making sense. The confusion came from the fact that I have a donor harness that came out of a later car. Grabbed it from a junkyard a few months ago when I was still planning on a 1.3 conversion. The way the multimeter was reading voltage on the solenoid wire in Run makes more sense if you know what unloader relays are!

I got everything wired today except the FP/main/O2 relays, VR sensor, idle valve, and the coil. The starter works, and I verified the fused point on the body harness connector that leads to the fuel pump. More good news, the fuel rail that I put together doesn't leak with the 3 bar fuel pressure regulator that I'm using (old eta configuration was 2.5 bar). Fuel pumps do not sound good though...

I still have a couple more questions though.

1. I think I want to relocate the relay block to the other side of the engine bay. There's a neat little spot for it in what would be the battery tray if this were a 318. Comes complete with a chassis ground point for the main relay. Is it ok to drill a couple of holes in this little web so I can bolt down a bracket for the relay block? I don't think it's structural. This also seems like a good place to have a catch can.
2. The driver's side is now left with brackets for the AFM and relay block that aren't being used anymore. Is there any reason that I shouldn't cut these out? I don't know if I'm going to reuse the stock airbox or not.
3. I do not see any good way to route the wires for the VR sensor. The bracket is on the exhaust side. I guess I could run it along the spark plug wire conduit, but this gives me worries about EMI, even though the cable is shielded. Thoughts? I'll be leaving a significant service loop in this cable in the event that I decide to convert to coil-on-plug later and decide to reroute this.
4. People with widebands: where did you mount your controller/gauge?
5. The blank harness I got came with the plastic split loom cover stuff. I've obviously ended up with a lot of branches and sections of reused BMW wiring that aren't protected. I have a special distaste for electrical tape. What should I wrap with? Bonus points if it comes in red, because that's +5 bhp.

It seems like a realistic goal to turn the key by the end of this week. Poor little eta has been parked for too long. This is honestly a lot of fun though. People seem to be afraid of wiring, but to me it's like a big logic puzzle. Just more pressurized fuel and high voltage.

[ForcedFirebird]

The battery tray is not structural. A lot of turbo builds remove them for down pipe clearance.

You can remove the brackets. I use a spot weld hole saw. Little tiny hole saw that removes just the area around the weld for a clean removal.

The stock routing goes behind the water pump pulley. The later model timing covers have holes for a plastic conduit to keep the wire from touching the pulley. Local here did a wire tuck in his race car and used the spark plug conduit for the CPS and it works fine. Just keep in mind the stock ECU is less picky about air gap. For MS I use a business card as a shim. To adjust, loosen the two 13mm bolts that hold the bracket to the block - the holes are much larger than the threads to allow adjustment.

WB gauge is preference, but the cubby below the radio works well, but a little out of line of sight. I usually mount the controllers in the glove box and use the factory o2 wiring to power and send signal into the cabin.

You can purchase plit loom just about anywhere. Home Depot even has a small selection. Pep Boys usually has the larger selection around here.

[flumph]

Good progress tonight.

I've wired in everything except the wideband, coil, and idle valve. Screwing in the hold down bolt for the VR sensor was something of a problem. The AC compressor is in the way of any socket that you would fit in there, and it's hard to get two hands down there because of the mess of coolant hoses. Relay block fits in the battery tray like it was meant to go there. I also noticed a concerning amount of oil on the exhaust side of my block. Not sure what that's about. Never noticed a drip. Valve cover gasket?

I did make a small mistake though. My crimping scheme mistakenly didn't allow for the positive on the primary of the coil. You're supposed to put this on the fuel pump relay, right? The wire I clipped from the donor harness is super thick and my connectors aren't that big, so it's going to get a bit messy there... Also not sure how I'm going to splice the wideband sensor ground into the sensor return. I almost got away without doing a single T-splice!

Unfortunately, it's supposed to rain again tomorrow (and probably the next day), so progress will slow. I will likely trace out how the idle valve needs to be handled (I have a 40 ohm power resistor to put on the closing coil) and power the car up for the first time tomorrow night, just to do a sanity check that all the sensors and outputs are working and that the IAT isn't reading 85,000 degrees. Maybe wire in the idle valve if it's not pouring.

[flumph]

Update!

The last crimp was made tonight. Everything got wired in except for the brown plug coolant sensor, which I'm not super happy about, but I'll have to live with it for now. The injector conduit I got fits a later style thermostat housing, so the plug doesn't reach (and I'm not honestly sure where that signal is supposed to go anyway). I had all the ring terminals down finger tight so I could pull everything back out once it was finished, and heat shrink all of my crimps at the same time, which I just finished doing.

I kind of left a lot of extra wire in a couple places, so it's not the cleanest looking job ever, but I'm kind of shooting in the dark here. There's a chance that I'll buy another pigtail (they're only $50 for an 8' one) and use this one as a reference to make a new one that's a bit better planned out. For now though, I think this will work just fine.

I do have one concern that I don't know what to do about, and that's the wideband sensor pigtail. Because I have stock eta exhaust, the sensor bung is in the midpipe, which required getting under the car. The factory routing has it jump across on the transmission crossmember, and then plug into a connector on the body harness. I don't think I'm comfortable just drilling a hole in my floor pan to duplicate this, so I just ran it straight up on the driver's side instead to avoid the exhaust manifolds. It does now come concerningly close to the steering shaft though, and I'm wondering if there's a good way to secure it to the firewall.

The AEM controller did come with a stainless bung, which I will have welded into a more reasonable location once I've got the car in a good enough running shape. Tomorrow, if I don't get too drunk, I'll run some preflight checks, comb over my tune file one more time, put the harness back in, and then hopefully I'll be tuning my idle on Saturday. Yes, I have a timing light.

Seeing what I've seen though, I'm really heavily considering stripping my interior and rewiring everything. This car really should be stripped and redone anyway. The PO was not nice to it, and I have more than one parasitic draw even without any kind of engine harness. That's next phase, I think. We'll see how that goes...

[flumph]

Update, probably the last one.

First crank today. It was quite an adventure. In my excitement, I tried to start the car without the MAP line plugged in. It actually managed to run for a few seconds! It runs SO much better than it did with the factory ECU though. Also, for anyone using this as reference, be sure that your ignition input capture is set to Falling Edge. If you don't, it gives you some weird lost syncs. Spent probably half an hour tuning the idle and I've got it dead solid with open loop. I hit it with a timing light and ended up advancing the trigger by a degree, but nothing crazy. The mark was easier to see than I expected.

Now I just have to clean everything up, connect the brake booster, rig the PCV up, figure out an intake (probably some PVC pipe with a cone filter on it for now), and go driving! This process has been so much fun and I want to say thanks to everyone who's posted in this thread. You guys are awesome.

[e30davie]

Nice work. Sounds like you are well on track.

For my wideband wiring i went up through the shifter hole. I kept out out of the way of the linkage under the car and then poked it through an existing hole in the gearbox rubber boot. The reverse light does the same thing so i figured it cant be too bad of an idea. I got a wideband bung put in basically right next to the gbox x member so theres not that much cable at all to deal with under the car.