1985 325e 2.7i NO start, on megasquirt

[kamotors]

so I finished up the 327i build for my friend, before I slap the turbo on I want to get everything squared away mechanically, so I went to start it today and it cranks over nicely, gets good oil pressure quickly, but is NOT getting fuel and also Tunerstudio is showing the ECU as not connected.

I've replaced the 3 relays out and still no fuel or ECU signal. Am I missing something that is needed when doing a 325i head swap on an 85e?I made my own harness from fuse box to engine harness and it went very smooth and 90% of colors matched right up from the 1987 I harness to the 85e fuse box harness.


I'll update with some pics tomorrow of questionable things on the harness I have. There is a thicker yellow and black wire that is capped off near the ECU and I'm not sure if its stock and also all the power wires to the power distribution block are put in to one large connector by previous owner.

the little plugs in the glove box are all disconnected for now but i hear the car will still start without them.

[kamotors]

photos of weird wire and fuse box.

[jlevie]

Tunerstudio saying that the DME isn't connected rather sounds like the MegaSquirt isn't powering up. Work it from that end to start with.

[kamotors]

would the fuel pump turn on without an ECU signal when cranking?

[Todd Black 88]

IMO, without a reference to piston position to the from a cps, there will be no fuel or spark. So if it says there is no ecu connected, you will get no signal, thus no fuel or spark.

[lcoleman]

Tunerstudio saying that the DME isn't connected rather sounds like the MegaSquirt isn't powering up. Work it from that end to start with.

Agreed. Get a connection before you go further--otherwise you're flying blind. Most setups are powered from the main relay, afaik.

would the fuel pump turn on without an ECU signal when cranking?

Factory fuel pump relay in my car is a switched ground from the MS unit. Wiring differed over the years, but I think this should always be true.

[kamotors]

the car has a complete 89 top end and 87 325i wiring harness, running my same turbo tune, the ECU never gets power with the key on, its as if its not hooked up. The fuel lines are bone dry and the pump never primes or turns on. its simply not getting power to MS at all.

normally in my 89 all I do is turn the key to run and all the electronics and MS comes to life, this car is showing no signs of that.

the service lights on the dash work, the oil pressure light on the dash works, the starter works great but the ECU is not getting power.

All of those things working tells me the harness is OK, which is whats confusing me, Ive switched out relays from 2 different harness one which was tested working and it doesnt make a difference.

[kamotors]

here is a connector that leads nowhere from the fuse box, dont know what its for.

ignore the nastiness, here is the ground location

and here is how the P.O of the wiring harness has the power wires run



I'm going to get new connectors for the power supply but pretty sure that wont fix any issues

[jlevie]

the car has a complete 89 top end and 87 325i wiring harness, running my same turbo tune, the ECU never gets power with the key on, its as if its not hooked up. The fuel lines are bone dry and the pump never primes or turns on. its simply not getting power to MS at all.

There is a difference between an 87 M20B25 and all harnesses from 9/87 on that might be significant. The START signal to the DME, that causes the main relay to close and thus powers up the DME in on a 3 pin connector near the DME connector. On later harnesses that input is spliced to the wire that goes to the coil positive.

[kamotors]

I believe I did see a 3 pin connector in the dash but it has no where to plug into on the 1985 body harness, where would I need to connect that to?

sounds like this is the issue


EDIT: found other end to 3 pring connector and now we have fuel and the ECU signal!

I threw on a tune but it still will NOT start, injectors are hooked up and the Tuner studio is reading a fuel load now while cranking, but injector pulse width while cranking jumps to about 5msec at the beginning of cranking but goes back to 0 as it cranks.

going to trouble shoot a bit more

[jlevie]

Not sure what is going on there, but at least the the MS is running now. Does the log show timing reference data for the entire time the engine is cranking?

[whodwho]

You mentioned you threw your tune on there, do you have the same injector size? Change the required fuel if not.

Also make sure that the project is set for Microsquirt module or it scrambles up the ignition settings and wont start

Not sure if you have the TPS hooked up, check that the TPS signal isn't creeping up past 70% or it will go into flood clear.

[kamotors]

and its ALIVE! and idles smooth.
so Jlevie was spot on with the 3 prong connector and then it was that the CPS sensor was plugged into the the wrong spot(the one that looks the same).

fired right up:) thanks everybody. now it just has an oil leak at a fragolla swivel fitting.