My Megasquirt 3 M50 setup

[dave.a.cote]

Hey guys - I am trying to do a M50 swap on Megasquirt 3 with MS3X and I think I have the ECU stuff done now but would like someone with experience to have a look over where I am at so far.

Please have a look at my thread over at the ms forums and give me any feedback you think will help.

Thanks.

http://www.msextra.com/forums/viewtopic.php?f=131&t=37175

[dave.a.cote]

A couple responses on the MS forum and it seems like everyone who is building one of these for a bmw engine is putting it in an e30!

[nando]

heh, yeah. I need to find a cheap ECU (can be any 88 pin motronic), buy the bare MS3 case and start building the adapter. Then I just need a harness..

[nando]

I updated the MS3/M3.3.1 chart:

http://www.megasquirt.325ix.com/MS_to_Motronic/MS3%20to%20Motronic%203.3.1.html

and created an C101 to X20 chart (for a 1990 E30/93-95 E36)

http://www.megasquirt.325ix.com/MS_to_Motronic/C101%20to%20X20.html

Feeling pretty confident about them. Spent way too much time reading ETMs. And there must be 100 different C101 to X20 charts, some of them way wrong (AGK's was terrible), so I made my own, verifying each function.

Here's a spreadsheet with everything I've collected so far:

http://www.megasquirt.325ix.com/MS_to_Motronic/MS3/MS3%20to%20Motronic%203x.xls

[dave.a.cote]

Ok so the car is drivable now, and it sure is nice. I still have a bunch of tuning to do but I think the tough stuff is behind me.

I have a problem with signals getting to the dash. I get no readings on my tach, the coolant sensor or the oil level sensor.

I bought a harness adapter from a r3v member. One wire was labeled as +12V switched. When I connected it to a switched source and turned the key on, it instantly started smoking and melted the insulation. I disconnected it and found out later that it is grounded! Could this be causing some of my other issues?

[nando]

what are you using for a tach output on the MS3? I use JS11 through one of the SPR pins on the V3.0 board. The stock E30 dash works great with the signal directly from the CPU.

the two possibilities are, you don't have the tachout pin hooked up or set up right, or whoever made your C101 adapter didn't build it right.

the coolant and oil levels are seperate issues most definitely related to the C101 adapter, they don't have anything to do with MS.

as far as the +12v, it could have been for the ABS system on late cars. They require a connection to the ABS relay, early cars do not. It's pin 20 for reference.

One reason I wouldn't trust somebody else to build me an adapter..

[dave.a.cote]

My notes say I have to MS3X Pin #26 wired to pin #74 of the BMW 88-pin plug. Maybe I screwed something up there.

Apparently the stock coolant m50 sensor will not work - I will try swapping in my old m20 sensor tonight and see if that fixes the temp signal.

[nando]

you mean pin 26 of the MS3x?

it's possble the 3x output doesn't work directly with our tach. I know for certain that running it through JS11 will work. Run a jumper from JS11 (v3.0 board) to one of the SPR pins (3, 4, 5, 6) and then connect that to the tach pin on the motronic harness. Of course you have to change the tach output to JS11 in the tuning software.

This also saves pin 26 of the MS3x for some other fun toy I'm sure you'll think of. :p

and yeah, the M50 (cluster) coolant sensor definitely does not work. It's 2 pins and grounds at the E36 cluster. the E30 sensor is 1 pin and grounds in the block. It doesn't work because it's not getting a ground signal.

[dave.a.cote]

I don't have to make any tach output circuit to use JS11? Just plug it in?

[nando]

yep!

I don't know why it would be different, but that's what I've used on a couple builds.

[dave.a.cote]

nando - thanks a bunch! JS11 worked like a charm. Turns out I had to swap a couple wires on the oil level sensor so that is working now too.

Now I have to replace one of the coolant sensors with the one from the m20 and I should be good to go.

My only remaining problem is pinging at high loads. Hopefully I can get that figured out soon.

[nando]

I know you've tried using very little advance, but would you mind posting your timing map?

[matt]

If you're using little advance, use more fuel.

[dave.a.cote]

I will get my timing table up in a bit. I am using a LC-1 wideband o2 sensor and it reads ~12.5:1 where I am getting ping (>90 kPa MAP and 4-5000 rpm). I looked at the plugs and I don't think that they look lean but they do show white specks which is a result of the pinging.

[nando]

How sure are you of the O2 sensor calibration? Have you checked the reading in logworks vs Tunerstudio? It sounds like they are correct but it's a good check.

Another thing, 4000-5000rpm is the peak torque area. It's generally going to be the place with the highest cylinder pressures and the biggest tendancy to knock. It could be that you are just knock limited in that area.

What about after 5000rpm, what kind of timing can you run up to redline? it should be a lot more than peak torque.

if it turns out you are knock limited (11:1 CR right?) you could get some agressive cams to bring down the dynamic CR a bit and shift the torque curve up.