E28 Megasquirt FAQ

[Owndapwn]

What do people do to add the shielded cable from the b35 crank sensor into a from scratch harness? Do people cut the cable before the large plug at the original location b35 injector box and add it to the new harness at that point, or is the large plug connection kept and the shielded cable pulled from the b35 up to the dme plug? I guess the question is, should the ability to unplug the sensor be kept or gotten rid of for a cleaner install? How important is keeping the shield on the cable all the way to the relay board?

Shielding is VERY important in an area that's exposed to the elements, or exposed to heat. Personally, I would (And will) heatshrink the bundle (Medium sized pack of assorted heat shrink is like $3 at Harbor Freight), and then put a nylon shielding sleeve over that. I intend to do this to the bulk of my harness when I have the motor out and can get to it all, as it really makes a difference long-term.
Unless you're talking about a heat shield type thing on the actual plug end, in which case, I couldn't tell you. But the wires themselves should be shielded if it's even remotely feasible to do so.

[BuzzBomb]

What do people do to add the shielded cable from the b35 crank sensor into a from scratch harness? Do people cut the cable before the large plug at the original location b35 injector box and add it to the new harness at that point, or is the large plug connection kept and the shielded cable pulled from the b35 up to the dme plug? I guess the question is, should the ability to unplug the sensor be kept or gotten rid of for a cleaner install? How important is keeping the shield on the cable all the way to the relay board?

Shielding is VERY important in an area that's exposed to the elements, or exposed to heat. Personally, I would (And will) heatshrink the bundle (Medium sized pack of assorted heat shrink is like $3 at Harbor Freight), and then put a nylon shielding sleeve over that. I intend to do this to the bulk of my harness when I have the motor out and can get to it all, as it really makes a difference long-term.
Unless you're talking about a heat shield type thing on the actual plug end, in which case, I couldn't tell you. But the wires themselves should be shielded if it's even remotely feasible to do so.

The shielding I'm referring to is electrical, to shield the wiring from interference. It is the third "wire" that is a woven steel mesh surrounding the other two wires inside the insulation. Kind of like coax cable.

[Owndapwn]

Has anyone got a hold of an MS3 yet? I was looking at the documentation for it, and it doesn't look like you'd need any sort of adapter for the Idle Air Control, Glen's Garage or otherwise.
It looks like, without having tried it or talked to anyone who has, all you would need is the MS3, trigger wheel, TPS, and IAT.

[BuzzBomb]

Has anyone got a hold of an MS3 yet? I was looking at the documentation for it, and it doesn't look like you'd need any sort of adapter for the Idle Air Control, Glen's Garage or otherwise.
It looks like, without having tried it or talked to anyone who has, all you would need is the MS3, trigger wheel, TPS, and IAT.

It's the same as MSII, except that the circuit for the 3 wire IAC valve is now native. The external connections are all the same as before.

[Owndapwn]

Has anyone got a hold of an MS3 yet? I was looking at the documentation for it, and it doesn't look like you'd need any sort of adapter for the Idle Air Control, Glen's Garage or otherwise.
It looks like, without having tried it or talked to anyone who has, all you would need is the MS3, trigger wheel, TPS, and IAT.

It's the same as MSII, except that the circuit for the 3 wire IAC valve is now native. The external connections are all the same as before.

So it does bypass the need for a GG IAC board? 'Cause that offsets the price difference, IMO.

[BuzzBomb]

So it does bypass the need for a GG IAC board? 'Cause that offsets the price difference, IMO.

Since GG isn't a reputable seller by any stretch of the imagination, I'd say it more than offsets the difference, if only the PITA factor of dealing with him.

[87M6chris]

Hi all, this is a great thread, have learned a lot reading it. I can't get my stock ECU working anymore so have decided to move to a MS system, I'm starting to collect stuff I need and just bought the 60-2 harmonic damper, crank sensor and sensor mount from a m30b35 engine. I mounted it up on the s38 but the sensor is not perfectly centered on the toothed wheel, how crucial is this alignment? I can shave the difference off of the sensor mount feet but not sure if this is built in deliberately or if I should adjust it.
Thanks for any advice you can give me,
Chris
[img][IMG]http://i682.photobucket.com/albums/vv185/87M6chris/DSCN0200.jpg[/img][/img]
[img][IMG]http://i682.photobucket.com/albums/vv185/87M6chris/DSCN0198.jpg[/img][/img]

[Kyle in NO]

Chris, that alignment is totally fine. I'd not mess with it.

[87M6chris]

Thanks Kyle,

Now that I'm installing MS I realized that I can get rid of the low impedance fuel injectors and enjoy the better selection of high impedance injectors and simpler set up over all.
The s38b35 engine uses a 24lb injector that just barley covers the HP of the stock engine so I'm looking at these,
https://www.fiveomotorsport.com/30lb-02 ... evil-bosch
they are 30lb which will allow me to push the engine to the 280 hp range.
The MS manual warns about not using too large of an injector because of possible idle problems but it doesn't say how much is too much.
Does the jump from 24lb to 30lb seem like too much or is the manual referring a much larger injector jump?
Thanks,
Chris

[tschultz]

No, you will be fine.^^

It is talking about 60+ lb injectors

[Owndapwn]

Target should be between 50% and 80% max duty cycle on the injector at full load.
70-80% is ideal if you're done, but if you plan on tweaking it and making more power, as little as 50% will have no issues, and still give you tons of room to move.

[87M6chris]

Thanks guys, that makes sense. The new injectors arrived from FiveO and the whole Megasquirt kit.
I'm wiring the relay board for the test stand, and the version I have MS2 357-C says it can handle our Bosch idle control valves without modifing the MS, PWM idle valve or Fidle, it says to run the middle Grn/Pur power wire from the ICV with fuel pump for power and run the negative wire from the ICV to the #6 Fidle terminal.
But our Bosch ICV have 3 wires, 1 power, 1 open, 1 closed, not sure how either open or closed could be considered negative?
[img][IMG]http://i682.photobucket.com/albums/vv185/87M6chris/DSCN0246.jpg[/img][/img]

[87M6chris]

Got an answer from Matt Cramer at DIYAutotune, "Run the "close" wire on the IAC valve to ground through a 10 ohm, 25 to 50 watt resistor." and I assume the open wire goes to #6 Fidle on the relay board and the power wire can double up with the fuel pump power wire.

[87M6chris]

I would be asking these MS questions on the MS forum if they would approve me, I tried to register over 3 wks ago and haven't heard anything from the yet.

Okay, so I have ironed out almost all the little problems and I'm very close to trying to start the engine for the first time, I have successfully done the fuel pump test, injector test, ICV test, still not sure if the coil test was right or not, I didn't hear any snapping of spark but the plugs are about 8" inside the engine. I will have to pull them and try that test again.
The thing that has me stumped is in the Diagnostics & High Speed Loggers section, can't get anything to show up on the screen when cranking the engine in Composite logger, tooth logger or sync error logger.
I tested the magnetic sensor with a volt meter and am getting 3-7 mv on a cranking engine, I have tried switching the wires from the crank sensor with no change in results.
Sort of dead in the water at the moment, any advice would be appreciated.
Thanks,
Chris

[smhheidari]

https://www.diyautotune.com/support/tec ... r-bmw-e30/

[downforce22]

https://www.diyautotune.com/support/tec ... r-bmw-e30/

the tooth #1 angle on the diy website is wrong for the m20. I think i'm running either 84, same as this e30 zone website. Whats the angle for the m30? http://www.e30zone.net/e30zonewiki/inde ... g_Your_M20

[tschultz]

Since the FAQ images aren't working, I figured I'd link a website that stole the content:

E28 Megasquirt FAQ



Compliments of Brad D. @ http://www.mye28.com


E28 Megasquirt FAQ
By Bradley Denton
Revised 01/06/10

Since there is a lot of interest in Megasquirt as well as a lot of people on this board either using MS or planning to, I felt that I would try to help add to the knowledge base. I don't know if the FI forum is the best place for this, but felt that since most of the MS users are FI guys as well, it was fitting. I am hoping this can be stickied as well, in whatever forum the Beamters deem appropriate. I hope as much of this information is as correct as possible, but I am human and occasionally make mistakes. If anyone has any questions, comments or corrections, please feel free to contact me. Enjoy!

What is Megasquirt?

Megasquirt (MS) is a DIY programmable standalone electronic fuel injection (EFI) computer. It performs many of the same functions as the factory Motronic unit in the e28 but allows the end user to adjust different parameters (fuel, timing, idle speed, etc) affecting how the engine runs. Since it is DIY, it is much less expensive than many other standalone ecus or even some piggyback computers. Megasquirt can be used to control fuel only or both fuel and spark. It is my opinion that for an e28 application you want to control both fuel and spark. It is also an excellent learning tool to understand how EFI works while making your car run better. You can read more about Megasquirt here. The user forums can be found here.

Why would I want to run Megasquirt on my e28?

The stock Bosch Motronic system in your e28 works well for a car in stock form. If many modifications are made to the car such as a large cam, high compression and headwork, or by adding forced induction (turbo or supercharger), or even a stock engine and you want to optimize things yourself instead of just installing a chip, fuel and timing maps will need to be modified for optimum performance. The stock Motronic can only be adjusted by altering the programming on the “chip” in the ecu. This is not the easiest way to tune your engine. You are also still left with the outdated architecture of the original Motronic system whose primary load input is a vane style air flow meter (AFM). By replacing Motronic with a MS unit you can now adjust fuel and timing maps, datalog, adjust your rev limiter, change idle speed, control electric fans, if you can think of it, MS can probably do it. Just plug in your laptop to MS, make your changes, save your tune, and you are good to go!

https://www.diyauto.com/manufacturers/b ... -by-brad-d

[tcturbo91]

I figure I would post here before making a new thread, I am currently running the Miller War Chip/MAF conversion for tuning on my M30 turbo project. I have had the car together for over two years now and with on and off tuning issues i'm ready to ditch it for Megasquirt. I'm looking for someone to build me a setup, was wondering if anyone on here still does this or can point me in the direction as to who would be a good person to enlist for a build. thanks!

[Owndapwn]

Has anyone done a full MS3+ install and thought to document some differences yet?

[1986series6]

http://www3.sympatico.ca/mdsylva/

http://www.davestuning.com/

[Shawn D.]

http://www3.sympatico.ca/mdsylva/

http://www.davestuning.com/

What's the point of your post? Mark D'Sylva makes great chips (I have one for my stock ECU and recommend them above all others), but he doesn't do anything for MegaSquirt. The tuner you linked to doesn't mention MS, and this is not a "tuner" thread anyhow.

[Owndapwn]

http://www3.sympatico.ca/mdsylva/

http://www.davestuning.com/

Mark's chips don't allow you to run launch control on a turbo car, so I'm not sure how you think the two are interchangeable while still assuming you know what an ECU actually does.

[Ju@n]

Has anyone done a full MS3+ install and thought to document some differences yet?

Late to the party, but yes, I have.
Only difference is since I have the MS3X board, I used the 3 pin ICV option on the software and used Idle and VVT pins on MS3X board instead of Fidle and resistor to ground as seen on MS2 installs. Works alright
The rest is mainly the same, going to install 6 LS2 truck coils as well as a distributor cover plate with a VR sensor later this year and create a custom wiring harness (instead of using the M1.3 one) so I can get Fully sequential injection and ignition.

[Owndapwn]

and create a custom wiring harness (instead of using the M1.3 one) so I can get Fully sequential injection and ignition.

Be sure to document your harness plans for us!

[turbodan]

I'm surprised to return to Megasquirt so many years later to find that my old settings don't seem to work well at all. Cranking pulsewidths on the current install are vastly different than before. Same engine configuration, may be differences in firmware. Who knows.

This time of year is the ideal opportunity to test cold starts. My old settings were far leaner than before, the new settings are as follows:

Cranking Pulsewidth %
Degrees F Pulsewidth %
-20 400
30 270
50 232
70 203
100 168
120 148
140 138
165 132
180 130
200 128

Afterstart Enrichment %
-20 47
30 35
50 30
70 25
100 18
120 13
140 9
165 5
180 3
200 2

Warmup Enrichment %
0 197
30 176
50 156
70 138
100 125
120 117
140 112
165 105
180 103
200 100

It started great at 33.5 degrees this morning. Tomorrow should be in the 17 degree range, that will be very interesting. The best cold start this thing ever did was with 24 degrees showing on coolant temp, which wasn't exactly perfect but it did light off with a reasonable cranking period and stabilize without sputtering out.

One setting I found that helped was to run the ICV before engine start, one of those things Motronic does that is easy to overlook. I think this setting may default to off in Megasquirt so it's one of those sneaky ones that has a subtle but negative effect. Having this "off" causes the manifold pressure to drop significantly when cranking begins but before the engine really lights off. Keeping MAP up near atmospheric increases cranking pressure and helps heat and vaporize cold fuel.

Warm starts are still perplexing, it seems to crank too long but only by a few tenths of a second. I was running much leaner settings, today I bumped the percentages up quite a bit. Will have to do some more warm starts to see how it responds. Ideally the car should sit for 15-20 minutes to allow any pooled fuel to cook away and dissipate. Restarting immediately after shutdown isn't nearly as common as restarting after 15-30 minutes of sitting while you're in the store for pretzels and beer.

As it is now the car runs great, way better than Motronic. No more weird idle behavior, no more odd driveability quirks. It's running the narrowband O2 feedback for fuel trims, saving me some gas. The car is ready for boost as soon as I get the turbodiesel manifold properly notched and build my intake plumbing. Even if I left it NA it would have been worth it, it's got more meat to the power. Motronic always felt to me like the power was flat, with some ebb and flow to the delivery. Same story with my last three or four e28's. Megasquirt with a proper fuel and ignition map delivers a power curve. The 528e now has a distinctive hit at 3000 RPM, feels like the M20B25 but it comes on and signs off about 1000 RPM sooner. Low end power is strong and smooth, throttle response is consistent and excellent.

Last time around I gave up on EAE. Didn't feel a need for it and I never could get it working properly. This time I'm running it full time. The current code allows both EAE and traditional AE simultaneously. EAE doesn't have to be perfect with the conventional AE online for quick throttle movements. They complement each other and EAE is always working during the kind of transitional throttle movements it sees constantly during normal driving. It's pulling back upwards of 20% of the fuel on throttle lifts to help maintain a reasonable AFR. Saves gas, less stink for the cars behind you. What's not to like.

[M. Holtmeier]

Which MS are you running and what firmware?

I'm seeing similar tuning irregularities after installing 1.5.2 firmware. Also having a vastly different air pump at the other end doesn't make for a straight comparison though.

[turbodan]

It is MS2 with 3.4.4 firmware if I remember correctly. I have no idea what I was running last time around back in the late 2000's but I'm sure it was different.

No dice on a one shot cold start this morning, the first crank was pitiful but it came to life on the second one. I am going to try flattening the cranking pulsewidth curve below 32F. It's interesting how it can be so good at 33.5 degrees and so bad at 20 something.

[iamcreepingdeath]

Howdy ladies and gents!

I don't know whether I should start a dedicated thread or not, so I will first start by posting here.

Background cliff notes: I am putting an MS2 V3.0 in my E28 w a M30B35 swap. Going to get it going NA first, then going turbo. I built the MS2, got it communicating w my PC, now I am trying to wire it into the car.

So I am using the wiring guide in the first post of this thread, but I have immediately run into an area of questionableness.

So pin 1 of the 55-pin B35 ecu is the ign coil wire, and it is FAT!! How the heck is that supposed to be plumbed through the DB37 connector to the MS2? Wouldn't the teeny DB37 pin and traces be way too tiny for the current needed in that fat black wire? I notice the Megasquirt pinout states that it is a 7A pin, which isn't all that much actually, but that wire size is most definitely sized to carry way more than 7A...

I am using a DB37 connector with it's own terminal block (at least to start out with) so it is easy to modify and change things later, until I get everything right, and I'll solder up a DB37 for real.

Here's the fat black ign coil wire from pin 1 next to the DB37 w/ terminal block that I intend to use


Pic of back of the B37 connector that I snipped all the wires from (and labeled each of them):


Note the size difference in general of the B35 connector and a standard DB37:


So... How did you all do the wiring from your engine harness to the MS2? I know DIYautotune sells some pigtails here: https://www.diyautotune.com/product/24- ... l-harness/, and it suggests using the DIYBOB here: https://www.diyautotune.com/support/tec ... re/diybob/, but why is it discontinued? What's the strategy with wiring in the MS2 with the DIYat pigtail? Just splice the wires together according to Brad D's table in the first post?

Thanks everyone!

[iamcreepingdeath]

I have found that the m30 tps is a bit different. Mine did not have the braided ground. You want to use the yellow, black and brown wires.

Brown - ground - splice it into any available MS ground

Yellow - signal - splice this to the tps signal in pin on MS

Black - 5V reference power. MS has a 5V reference voltage output.

Quoting this post here, because this seems to be true for the M30B35 TPS. The 55 pin wiring table in Brad's first post in this thread is therefore incorrect. Those ECU pins 52 and 53 are NOT the correct wires needed for the 5V ref and TPS signal to feed into the Megasquirt. I don't know what those wires are used for originally, but what you want to run into MS2 pin 22 is the yellow signal wire from the TPS sensor, and into MS2 pin 26 you want to run the black 5V wire from the TPS.

I don't know if those wires are already present in the Motronic 55 pin connector (I don't think they are), so you would have to run those wires yourself from the TPS to the MS2. They are also shielded in the factory wiring harness, so I don't know how critical it is to make sure they stay shielded...

[badgerpants1872]

Hello. I have an '86 535i with an 059 ECU. Currently it has a Miller MAF and base chip, intake, and downpipe-back exhaust.

Ultimately, I feel like an engine swap is the way to go and so I don't want to sink a ton of cash into making big power with the M30. I think I'll just twiddle my thumbs until B58 donor cars come down in price.
However, I feel like Schmiedmann manifolds, wasted spark, E85 flex fuel, and a 100 shot of nitrous would be perfectly reasonable and responsible with an estimated 300-325 wheel torque in the mean time and I should be able to manage this for around $5-7k.


That said, I'm looking at an MS3 ( https://www.diyautotune.com/product/meg ... lack-case/ ) and have reviewed the documentation about adapting the factory harness, but I'm curious if anyone has built and documented a fresh new MS specific harness using one of their loom kits ( https://www.diyautotune.com/product/10- ... ms3-ready/ ) to replace our ancient wiring from back when a 5.25" floppy disk was the most advanced thing on the planet. Can't tune away a repair problem and all that. And if my naked eye can see my injector plugs crumbling to bits, what electrical damage can I NOT see?
I've extensively used the search function, but it's (I'm) not all that smart here and pulls up a lot of unrelated noise.
It'd be nice to be able to delete unneeded or damaged circuits with a brand new harness, but I reckon it'd be a huge pain in the ass, as well as complicate the whole working instrument cluster thing.


Additionally, if I retain the factory harness, has anyone heard anything about the E28Goodies PNP solution? https://e28goodies.com/product/m30-motr ... grammable/
It's effectively an MS2 pigtailed to the factory 35-pin stuffed inside a sheet metal box. I'm not against an MS2, but there's virtually no cost difference between MS2 and MS3, and the MS3 is objectively quite a bit better.
Unless I'm overlooking something from AMP EFI that's viable. I see they offer an MS2 base solution for the E30/E32/E34 55-pin straight sixes ( https://www.ampefi.com/product/mspnp2-8 ... -e30-325i/ ) but nothing for the MS3Pro PNP.
I do have the ECU-side 35-pin plug from a cooked 059 ECU, and would be able to use that with a DB37 pigtail to get something almost PNP.


Just curious to see what the modern doctrine is. The OP was from sixteen years ago, so it's mostly a wiring document at this point. I mean, those are Windows XP screenshots.