Megasquirted E36 runs, some questions.

[Kingbob]

first off I'm not sure if this is the right forum, but I noticed a lot of the other megasquirt threads are in the e30 forums. Mods feel free to move as needed and appologies in advance for the possible misplacement.

I just finished building a Megasquirt for my little brother's (Dakar318) '92 325is. I used goathumper's notes and guide for the PNP harness build. His guide is for an e34 chassis m50 but fromw hat I can understand it should be the same. I compared his notes to a Bently manual wiring diagram for the 3 series.

Some differences i found:
OEM ECU - Megasquirt
54 - 28 should be 56-28, connecting per goathumpers notes the ECU runs even with the key off
70 - 23 should be 70 - GND per bently manual
71 to GND should be 71 - 23 per bently manual

the 70 and 71 bit I haven't confirmed yet.

Also I don't think anyone's said this yet, but If you gut a stock ECU for the connector you can also take the Ignition drivers too. They connect the same way as the VB921s.

My question is, When i connect the harness the fuel pump comes on stays on. I'm scratching my head on this one. It stays on whether or not the key is on. It works normally with the stock ecu in place so it must be something in the harness, or missing from the harness. Any ideas?

Also I connected the TPS per the bently manual but it's always at 99% reguardless of position. I should be able to figure this one out as it's only 3 possible combinations. but I'd aprecciate anyone's input there.

Has anyone figured out the easytherm settings for the stock IAT and CLT? Is the stock IAT part of the MAF sensor or is it located elsewhere? If the IAT is part of the MAF i'll just pick up the GM IAT and not worry about it. I'd rather keep the stock CLT sensor so I can swap out the OEM ECU when necessary

[andrewzpsu]

I'm sorry to ask, but what is Megasquirt?

[carbon monoxide]

i'm sorry to ask, but what is megasquirt?

engine management.

[5mall5nail5]

If the fuel pump is coming on that means the MS harness is grounding the pin for the fuel pump relay. Look at the wire for the fuel pump turn on on the MS side - its pin 37 on the MS connector. If that pin is somehow being grounded, or if the fuel pump wire on the Motronic side is being grounded, the fuel pump will run whether the car is on or off.

[Kingbob]

so the relays get constant 12v on the power side and not switched? I'll have to tripple check my harness.

On the PNP thread it shows building a seperate relay control circuit for the other relays, I connected them all to the Fuel pump relay. I'm still not good reading the diagrams for relays so could it be possible the other relays are grounded and looking for a high signal to switch? if so that'd be where the FP relay is getting it's ground from.

edit: i forgot to note that I'm using a MS-1 v2.2 I used the 2.2 because it's cheaper, I'm more familiar with that unit (as this is my 3rd), and I had an unused LM1815 circuit built and lying around. I think for the next car I do I'll run a V.3.0 or a MS2, not sure yet.

[Kingbob]

oh, Does anyone know a good vacuum source for the map sensor? I thought about T-ing off the FPR line, but It looks like a serious pain in the butt to get to, buried underneath the manifold

[Kingbob]

wow, this forum moves fast. the multimeter can't find any shorts in and around the FP relay pins on either connector

[Goathumper]

The FP wire should be connected to megasquirt db37. Im not quite sure what you did with the relay pins. The pinout has been tested correct. The "relay circuit" triggers the main relay when the key is turned and feeds power to everything else in the harness including ecu pin 54. If you grounded the main relay pin and the fuel pump pin, they would both always be on.