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bmwbav
bmwbav New Reader
5/28/14 3:24 p.m.

In reply to RoughandReady:

"Might be a stupid question, but what do I really need to run the engine fuel wise? CIS seems to have so many redundant and overlapping parts. I have less experience with modern-ish EFI than I do with K-jet (all my cars have been old as dirt). So I need a MAP, TPS...RPM, temperature, idle control?"

Look at a wiring diagram, it should be pretty clear. http://www.msextra.com/doc/general/ms2external.html

bluej
bluej SuperDork
5/28/14 3:40 p.m.

OK, thanks. It's for an 80's sixpot running the earliest Bosch motronic, so not far off from you anyways.

I have an MS1 V2.2 board that I've had for years now that I'd like to finally put to use on my recently low pressure turbocharged '86 325e e30 bmw.

End goal is a squirt n spark setup using the LSx COP's I already have, but in the mean time I need to get it up and running on fuel only as soon as possible.

First off, it seems the easiest way to get up and running would be to setup the MS in a "piggyback" mode and leave spark up to the stock ECU, pulling engine timing from the single coil. The question is due to the nature of how the stock ECU controls ignition. The six cylinder e30's have a rotor/distributor attached to the end of the cam, with a "swipe" type of contact on the rotor. The ecu grounds the stock coil for spark signal, advancing/retarding as necessary, which the swipe nature of the rotor contact allows for.

Does that mean that I will not be able to use that signal for engine timing to control fuel? I understand that with batch fire, the timing isn't quite THAT critical, but I don't know if the variance due to the ignition advance/retard is something that can be tuned around.

If it's a problem, the later versions of these motors use a crank trigger wheel/sensor setup behind the crank pulley that is easy to retrofit, and I'd eventually be going that route. Not having to source the parts yet would allow me to get the fuel-only setup up and running sooner to be safer than the rising-rate fuel pressure regulator that I currently have installed.

Another option that occurred to me: just pull the rpm signal from the stock ecu tach output? I think I read somewhere you just need to set the input type to hall/optical? I could just keep the stock ECU long term and let it play nice with things like the stock gauges in this case.

Two more questions, and I'll try to be brief since this is a bit of a novel:

IDLE: The early e30 eta's have a separate idle control module from the stock ecu that controls an ICV similar to the one pictured above. Any reason I can't just keep this and not use any sort of idle control through the MS?

TPS: The stock TPS is the kind like RoughandReady described above, where it's basically two switches that close when the throttle plate is either closed or at WOT. If I'm not going to use the MS idle control, will that work for speed density/hybrid or do I need the potentiometer type?

Thanks, sorry for the novel!!

bluej
bluej SuperDork
5/28/14 4:17 p.m.

I just realized that I won't be able to use the stock ecu tach output for the ignition trigger long term since it won't tell me position, just speed. doh.

I was just starting to read about dual sensor/trigger input setups. (http://www.msextra.com/doc/ms1extra/MS_Extra_Ignition_Hardware_Manual.htm#2senscrank) These cars use a dual VR crank sensor setup. One senses engine RPM from the flywheel ring gear teeth. The other is a TDC position sensor that reads off a single extra tooth on the flywheel farther back from the ring gear. Would I be able to use the stock ecu tach output as a hall/optical and then the second VR for crank position like in the link above? I remember seeing somewhere that you can't use the ring gear sensor for crank speed because MS can't handle a wheel with that many teeth.

bigdaddylee82
bigdaddylee82 Dork
5/28/14 6:00 p.m.

While we're at it...

I've read the DIYAutotune FAQ about "Installing MegaSquirt in Parallel with the Stock ECU" a few times, but the typical search results I get when searching for actual parallel/piggy back implementation are a bunch of people shouting, "why would you piggy back a stand alone?"

I've thought a lot about a particular project that involves forced induction, on what is considered by the masses to be a castoff, worthless engine. The general decree is "engine swap" and/or "sell it." While I dare to be different, this particular platform doesn't get a lot of support and is OBDII/CAN-bus. I'd like to retain the stock gauges, A/C control, transmission control, etc. and still have a reliable tunable engine management. It seems to me that the correct answer is, Piggy Back, no?

As complete and powerful as Megasquirt is, combined with Tuner Studio, in my mind at least, it far outshines the "piggy back" controllers offered from the likes of Split Second, or AEM's FIC.

I guess I said all of that to ask, is Megasqurit the right/best answer for scenario like I described above?

While I'm at it, anyone have first hand experience, with Piggy Backed MS, and what all did you control with it?

  • Lee
bmwbav
bmwbav New Reader
5/28/14 6:07 p.m.

In reply to bigdaddylee82: I can't speak from experience on the piggyback set-up. However, I see issues with using megasquirt, or any standalone for that scenario. To keep your stock OBD2-CANBUS ECU relatively happy, it's probably going to want to see a lot of the sensors that megasquirt would need to operate. You can't share the sensors between the ECU's and still retain accurate measurements. It's not insurmountable, but it's definitely more of an electrical engineering problem than just replacing the stock ECU.

turboswede
turboswede GRM+ Memberand UltimaDork
5/28/14 7:09 p.m.
RoughandReady wrote: I thought the CIS fuel pump ran at a pretty high pressure (like 90 psi or something?), maybe an LH pump or a Walbro or something might do me better? As for a TPS, do I need a constantly variable kind or can I use something like later Volvo 240s had, where it's basically 3 microswitches in a box?

An EFI rated regulator will work fine with the CIS pump. Did on my 924 before the pump died and I used a Walbro to replace it. No changes to the fueling were needed when switching pumps.

Technically you don't "need" a TPS. But it helps to have one. You'll want one that is constantly variable 0-5v.

Some have adapted MAFs to their MegaSquirt, but that's a whole 'neither can of worms.

RoughandReady
RoughandReady HalfDork
5/28/14 7:40 p.m.
turboswede wrote:
RoughandReady wrote: I thought the CIS fuel pump ran at a pretty high pressure (like 90 psi or something?), maybe an LH pump or a Walbro or something might do me better? As for a TPS, do I need a constantly variable kind or can I use something like later Volvo 240s had, where it's basically 3 microswitches in a box?
An EFI rated regulator will work fine with the CIS pump. Did on my 924 before the pump died and I used a Walbro to replace it. No changes to the fueling were needed when switching pumps. Technically you don't "need" a TPS. But it helps to have one. You'll want one that is constantly variable 0-5v. Some have adapted MAFs to their MegaSquirt, but that's a whole 'neither can of worms.

Okay, cool. My concern was putting too much stress on what will most likely be a pic-a-part FPR.

A Volvo LH 3.1 throttle body appears to be what I want. I think also fairly scrap yard common. I foresee a log manifold being made instead of dealing with the stock manifold. Yeah, cool long runners, forget wrenching on anything below it and kiss anything goodbye that you drop.

bigdaddylee82
bigdaddylee82 Dork
5/28/14 10:11 p.m.
bmwbav wrote: In reply to bigdaddylee82: I can't speak from experience on the piggyback set-up. However, I see issues with using megasquirt, or any standalone for that scenario. To keep your stock OBD2-CANBUS ECU relatively happy, it's probably going to want to see a lot of the sensors that megasquirt would need to operate. You can't share the sensors between the ECU's and still retain accurate measurements. It's not insurmountable, but it's definitely more of an electrical engineering problem than just replacing the stock ECU.

The way I understood it, Megasquirt wouldn't necessarily need/have to share any sensors with the original ECM, Megasquirt would have it's own sensors. That could make for a mess of spaghetti wiring, and some extra challenges with stuff like the TPS. Original injector wires go to the Megasquirt, and Megasquirt controls the injectors.

bmwbav
bmwbav New Reader
5/28/14 10:59 p.m.

In reply to bigdaddylee82: Yes, you're right, that would work, more of a logistical challenge than electrical engineering at that point.

MadScientistMatt
MadScientistMatt UberDork
5/29/14 7:31 a.m.
RoughandReady wrote: I don't really need a fine control of the idle. It's getting old and had never really idled where it's supposed to or without some coughs, weezes, and sneezes. If it had a constant idle at the correct rpm, I'm happy. The car will be a daily driver, so I think simple = better. Even a MAP is pretty new, i'm more used to MAF's and air flappers. haha.

You can simply set the idle speed with a set screw. That will give a higher idle than what's possible with an IAC valve when the engine is hot if you set it high enough to keep it from stalling when cold, but that's not a big deal. You can start without the IAC valve and add it in later if you're so inclined.

I thought the CIS fuel pump ran at a pretty high pressure (like 90 psi or something?), maybe an LH pump or a Walbro or something might do me better?

It does and you don't need to change out the pump. Just the injectors and pressure regulator.

As for a TPS, do I need a constantly variable kind or can I use something like later Volvo 240s had, where it's basically 3 microswitches in a box?

MegaSquirt does not use a switch type TPS - you could either use a potentiometer type or run without one.

MadScientistMatt
MadScientistMatt UberDork
5/29/14 8:01 a.m.
bluej wrote: I have an MS1 V2.2 board... End goal is a squirt n spark setup using the LSx COP's I already have, but in the mean time I need to get it up and running on fuel only as soon as possible.

Easiest way to trigger the ignition is the later M20 crank trigger, but this will require adding a VR conditioner (like the Zeal daughter board) to use the stock sensor.

The question is due to the nature of how the stock ECU controls ignition. The six cylinder e30's have a rotor/distributor attached to the end of the cam... Does that mean that I will not be able to use that signal for engine timing to control fuel? I understand that with batch fire, the timing isn't quite THAT critical, but I don't know if the variance due to the ignition advance/retard is something that can be tuned around.

You don't even have to tune around it - in practice, this is a non-issue. Batch fire isn't very sensitive to fuel timing at all.

Another option that occurred to me: just pull the rpm signal from the stock ecu tach output? I think I read somewhere you just need to set the input type to hall/optical? I could just keep the stock ECU long term and let it play nice with things like the stock gauges in this case.

That should work OK too as long as it puts out enough current to trigger the V2.2's optoisolator.

IDLE: The early e30 eta's have a separate idle control module from the stock ecu that controls an ICV similar to the one pictured above. Any reason I can't just keep this and not use any sort of idle control through the MS?

That's what I'd do.

TPS: The stock TPS is the kind like RoughandReady described above, where it's basically two switches that close when the throttle plate is either closed or at WOT. If I'm not going to use the MS idle control, will that work for speed density/hybrid or do I need the potentiometer type?

Just ignore the TPS and use MAP for everything. That's how the MSPNP works on the later E30s, although it has provisions to allow adding a variable TPS.

I just realized that I won't be able to use the stock ecu tach output for the ignition trigger long term since it won't tell me position, just speed. doh.

Not as big an issue as it seems - a batch fired, fuel only install doesn't need engine position, just speed.

bigdaddylee82 I've thought a lot about a particular project that involves forced induction, on what is considered by the masses to be a castoff, worthless engine. The general decree is "engine swap" and/or "sell it." While I dare to be different, this particular platform doesn't get a lot of support and is OBDII/CAN-bus. I'd like to retain the stock gauges, A/C control, transmission control, etc. and still have a reliable tunable engine management. It seems to me that the correct answer is, Piggy Back, no?

That seems reasonable to me.

bluej
bluej SuperDork
5/29/14 2:03 p.m.

Thank you, Matt!

So i guess my last question for now, can you run a mix of sensor types, ie: hall/optical for rpm and a separate vr for crank timing (single tooth on bmw eta fw in this case)? I'm thinking for fuel and spark as phase II.

MadScientistMatt
MadScientistMatt UberDork
5/29/14 2:16 p.m.
bluej wrote: Thank you, Matt! So i guess my last question for now, can you run a mix of sensor types, ie: hall/optical for rpm and a separate vr for crank timing (single tooth on bmw eta fw in this case)? I'm thinking for fuel and spark as phase II.

The same sensor(s) is used for timing and RPM, but you can use different types for crank and cam sensors if you have a setup that calls for that. An MS1 on a M20 motor, you're best off with a single crank sensor for fuel and ignition.

bluej
bluej SuperDork
5/29/14 3:35 p.m.

Do you think a single tooth crank trigger would potentially work if MS was set to read it as a two tooth cam trigger if using different types of sensors? I understand that adding the 60-2 wheel from an "i" m20 motor is the best option, I'm just curious if there's a way to do it with the stock eta m20 hardware and sensors.

bentwrench
bentwrench Reader
5/29/14 4:58 p.m.

Actually a 60 tooth crank wheel is not the best.

The frequencies get pretty high in the upper RPM ranges with 60 teeth.

A 36 tooth wheel is a much better source.

The smallest I would run on a crank is 12 teeth. I like numbers that evenly divide into 360, integers not allowed.

I don't think one tooth will fly. TS will take the setting but I don't see it working well.

bluej
bluej SuperDork
5/29/14 5:36 p.m.

I know there are a bunch of 60-2 setups running around on e30's since that was a stock wheel setup for many of these motors. I could grind off every other tooth, though, to make a 30-1. What qualifies as upper rpm? Redline is sub 5500 due to cam bearing count and cam profile.

MadScientistMatt
MadScientistMatt UberDork
5/29/14 8:45 p.m.
bluej wrote: Do you think a single tooth crank trigger would potentially work if MS was set to read it as a two tooth cam trigger if using different types of sensors? I understand that adding the 60-2 wheel from an "i" m20 motor is the best option, I'm just curious if there's a way to do it with the stock eta m20 hardware and sensors.

For fuel only, but not for ignition.

If the motor revved to 10,000, I might worry about MS1 not keeping up with 60 teeth - but for an eta motor, it'll be fine. (And MS2 can handle 10,000 RPM on a 60-2 wheel without breaking a sweat.)

bluej
bluej SuperDork
5/30/14 9:19 a.m.

Thanks, Matt!

yupididit
yupididit GRM+ Memberand New Reader
5/31/14 9:56 p.m.

Funny I was thinking what it be loke to run MS on the 450sel and get rid of the kjet and emissions stuff.

bentwrench
bentwrench Reader
6/1/14 9:02 a.m.

I want to do a MegaSquirt and a CNG conversion for a DD.

No emissions testing, no road tax, a ridiculously small percentage of fueling cost, never have to go to a gas station again, plug it in in the garage fills itself overnight, quadruple motor oil change interval, high octane (BOOST!).

Knurled
Knurled GRM+ Memberand PowerDork
6/1/14 11:02 a.m.
MadScientistMatt wrote: It could if your engine was exactly the same and you were running the same hardware and firmware. Otherwise, the tune may be a starting point, but will need some final adjustments.

When I first started playing with Megasquirt, a "known good" tune was as much as 40% off from what I needed. The fuel curve was shaped all wrong. The injector constants were also massively off and the PWM settings were not feasible. A day's worth of learning and tweaking fixed all that. It was fun.

Flash forward six years, and my 1.01 box let the smoke out when the battery came disconnected while driving. Oops. The laptop with the latest tune is nonfunctional, so I just popped the chip out and threw it into a MSnS-built box I had lying around after verifying that being configured for VR signal would work with my distributor setup. Starts and runs great, although it doesn't turn on the fuel pump on first key-on anymore (...huh) and fuel economy is a much lower now, I'm seeing 12-16mpg instead of 20-24mpg. Same tune, same firmware, same car, just different box.

Knurled
Knurled GRM+ Memberand PowerDork
6/1/14 11:06 a.m.
bentwrench wrote: I want to do a MegaSquirt and a CNG conversion for a DD. No emissions testing, no road tax, a ridiculously small percentage of fueling cost, never have to go to a gas station again, plug it in in the garage fills itself overnight, quadruple motor oil change interval, high octane (BOOST!).

All of the parts to do this are readily available in the aftermarket. The injectors drive like normal injectors too.

Every CNG conversion that I've seen would run on gasoline for a minute or two to warm the coolant enough to keep the pressure regulator from freezing as it drops ~3000psi gas down to working pressures. You should still be able to work around this.

Paul_VR6
Paul_VR6 HalfDork
6/1/14 11:29 a.m.
Knurled wrote: Same tune, same firmware, same car, just different box.

If they arent the same board version, I believe it the injector drivers changed from v1.01, 2.2, v3

Knurled
Knurled GRM+ Memberand PowerDork
6/1/14 12:10 p.m.
Paul_VR6 wrote:
Knurled wrote: Same tune, same firmware, same car, just different box.
If they arent the same board version, I believe it the injector drivers changed from v1.01, 2.2, v3

Would that make a significant difference given that I am running through a resistor block with PWM disabled?

I'd have to buy a new wideband sensor to tweak the tune (every time engine sucks oil, it kills the wideband) and the bung got crossthreaded and I'm thinking that it's easier to just spend an extra $200/mo in fuel than be arsed to fix it right now.

And then I'd still have to try to find a copy of Megatune to tweak with, since TunerStudio locked itself out unless I updated, and the new version does NOT run on it. Le sigh.

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