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Has anybody run an s38 on megasquirt? I am contemplating it due to the adjustability it has. Note this would be for the S38B36 which is a bit different from the e28 B35. (AFM, 60-2 CPS, intake flapper valve)

- IAT sensor
- 60-2 CPS
- MAF (not AFM)
- 55 pin Bosch motronic 1.2 350 ecu

The main difference between other applications would be:
-switch style TPS, either upgrade to vTPS from M50 or use auto e34 TPS
-tune for alpha n or ITBs
-double check wiring diagrams for premade ecu (for m20) vs s38 pinout

Am I missing anything? It seems to me the MS2 would be a worthwhile upgrade of the S38, are M5 owners too much of purists to deviate from the stock ecu?

Page 135 has the ecu pinout for the s38b36 for future reference
http://www.armchair.mb.ca/~dave/BMW/e34/e34_93.pdf

E30 M1.3 ECU pinout:
http://www.e30zone.net/e30zonewiki/i...hp/ECU_Pinouts

It looks like a few things are different between the ECU pinouts, mainly the following pins related to AFM and an auto trans that came with the m20.

Pin 7 - Mass air flow vs AFM
Pin 12 - Not Used vs AFM Reference
Pin 23 - Air Pump relay vs O2 Sensor Heater
Pin 25 -Preheat MAF vs Not used
Pin 26- MAF ground vs AFM ground
Pin 32 - (maybe) Measuring signal to OBC vs econometer
pin 43 - MAF vs Not used
pin 50 -not used vs ABS fuel cut override
pin 51 - not used vs auto kickdown
pin 54 - fuel coding signal vs torque converter lockup switch

I'm guessing pin 23 is the actuator for the intake plenum valve? It would be nice to keep that feature somehow. I would obviously need a widebad to get it tuned but once that was done it could be set it and forget it, right?

There is no reason why you can't do this. I'm not sure there is not a ton to gain unless then engine has been significantly modified beyond what the stock ecu can control.

As you've laid out, there will be some minor changes in wiring from MS to the 55pin connector that will need to be made.

You can run the motor off of MAP if you "T" the vaccuum signals between the throttle and head. MS2 can also output a signal to run the intake flapper. You'll lose the MPG in the dash if it currently works.

I'm not sure if the s38b36 injectors are high or low impedance. I seem to recall that s38b35 injectors are low impedance. If they are low impedance you'll want to limit current in your injector output. Otherwise, assuming you've wired it correctly you could most likely start the car with a a base M30 tune.

George wrote:you could most likely start the car with a a base M30 tune.

Megasquirt has an S38 tune built into their software, this is the tune we started with on my M90 with an S38B38 crank.

I would talk to DIYAuto about using low impedance injectors if that is what is used on an s38b36. My understanding is the controller is not set up for low impedance injectors. In addition you will need to convert to a 1.3 harness.

OcCoupe wrote:

George wrote:you could most likely start the car with a a base M30 tune.

Megasquirt has an S38 tune built into their software, this is the tune we started with on my M90 with an S38B38 crank.

I would talk to DIYAuto about using low impedance injectors if that is what is used on an s38b36. My understanding is the controller is not set up for low impedance injectors. In addition you will need to convert to a 1.3 harness.

You just limit current so you don't burn up the driver - I run low impedance on my MS2 controlled car.

George wrote: You just limit current so you don't burn up the driver - I run low impedance on my MS2 controlled car.

Got it! That makes sense.

I am looking into this on the S38B36 which uses a 55 pin ecu and high impedence injectors vs the S38B35 that uses 35 pin motronic 1.0 and i'm assuming the low impendence injectors. Here is a list with info on bosch injectors: http://users.erols.com/srweiss/tableifc.htm

The B36 uses the 0-280-150-701 which flows somewhere from 240 cc at 3 bar to 270 cc depending on where you get your info.



It may be necessary to build a circuit to run the intake flap, which would essentially be a Boost control solenoid. If you have a switch set at a specific engine map it would output a certain signal from the ecu to open the flap. You could choose the point where this occurs, maybe by rpm or by engine map and adjust it to what may work best.

I just picked up another megasquirt unit so i may try to see about runinning the engine with that

Switch point for the flap are 4120rpm, and yes it makes a difference.
I have an MS2 .msq for the S38.

any chance you could share your msq for the s38?

downforce22 wrote:any chance you could share your msq for the s38?

Pm sent.

Bert-Ola wrote:

downforce22 wrote:any chance you could share your msq for the s38?

Pm sent.

Hello... I am almost ready to start my S38B36 ... running MS2 extra 3.4.0 Could you share your MSQ file to me as well?

Thank you

BTW - I have been setting it up to run the intake flap on the plenum.

PWM triggering vacuum solenoid through a relay that is running through the oem evap purge valve harness (has the correct two prong plug)....logic on MS, when TPS is over 90% plus RPM over 4120.

Vacuum actuator is NLA ... located this one for a Prosche https://www.ecstuning.com/b-genuine-por ... 811016001/ and it connects perfectly to the plenum mount. The arm is too short so extended using remote control car turnbuckle and nylon ball joint end.

Once started and confirmed working I will write it up with pics... I am on the home stretch of what has turned an engine swap into a 3 year project due to a broken #1 piston, and ambition creep.

2wheelsoff wrote:BTW - I have been setting it up to run the intake flap on the plenum.

PWM triggering vacuum solenoid through a relay that is running through the oem evap purge valve harness (has the correct two prong plug)....logic on MS, when TPS is over 90% plus RPM over 4120.

Vacuum actuator is NLA ... located this one for a Prosche https://www.ecstuning.com/b-genuine-por ... 811016001/ and it connects perfectly to the plenum mount. The arm is too short so extended using remote control car turnbuckle and nylon ball joint end.

Once started and confirmed working I will write it up with pics... I am on the home stretch of what has turned an engine swap into a 3 year project due to a broken #1 piston, and ambition creep.

great progress, keep us updated

Anything ever come of this Porsche plenum flap actuator mod? Interested in trying it on my own s36 plenum.

I’m also going to use MS2 on my s38.