Spark+Fuel but no start--S50

[Steven]

First thing to do is swap out or at least clean your relay contacts.

I've tried 3 different relays...

[e30style]

What dme are you using? You said the computer is good but Did you swap chips? Make sure the chip is in correctly and seated completely.

[Steven]

Okay, I realized that the main relay I had in there was a four prong not a five prong, alright, stupid me. Now I'm getting power to the red/white wire, but it's constant without the key even in. Meaning that even when the key isn't in, the ICV and everything else is getting power and running...

[Steven]

Still no spark though.

[Steven]

changed out that relay now I'm good with the IVC and everything. /now I'm just not getting any power going to the green/violet wire when the car is turned over and once again no spark.

[Nick_S]

I tried my new DME's and another used but tested good CPS. Still not firing. Sprayed some fluid in the intake and it runs for a second and dies so I have spark. Tested the injectors with it cranking and they're still not seeing power. Ordering a new crank sensor tomorrow. Should have bought a new one in the first place.

[e30austin]

DME grounded properly? You made sure that the thickest green wire on your E36 harness (where you spliced the x20 end to a C101 connector) has a little green wire with it and is getting power?

[Steven]

DME grounded properly? You made sure that the thickest green wire on your E36 harness (where you spliced the x20 end to a C101 connector) has a little green wire with it and is getting power?

Little green one is getting power. I believe it is grounded, yes

[Steven]

So yesterday I was just messing with stuff on it, not doing much, and randomly got fuel and spark. Maybe something was just stuck or something? At any rate it fires for a couple times and then dies. Idk why. Now another shitty problem to figure out

[Wanganstyle]

So yesterday I was just messing with stuff on it, not doing much, and randomly got fuel and spark. Maybe something was just stuck or something? At any rate it fires for a couple times and then dies. Idk why. Now another shitty problem to figure out

Do you have the BMW factory service wiring manuals printed out?

did you verify the water temp sensor and other plugs under the intake manifold are correct by checking continuity to the DME plug position? if you don't have the wiring printed out and a chart drawn up of WTF you are dealing with it will stay dead a LOOONG time.






- this is usually the #1 cause of no start swap; installer fucked up by putting wrong plug on wrong sensor. been there done that wrote home about it.


the M50 engine only needs crank position sensor, water temp sensor, 6 coil packs and 6 injectors functioning to fire, IAC to idle.

unplug the airflow meter and see if the idle improves; if it does you likely have a dead AFM or vacuum leak between the AFM and IAC.


realistically if the engine harness has power and ground connected properly (and no shorting created by installer), the engine will fire and idle with no water, no radiator, no intake boot or airflow meter connected, o2 sensor is not needed for fire and idle either.

Our racing M50 has 2 wires going into the OEM bmw engine harness and the rest all longacre racing inthe body.

only 2 wires are needed for a race car to the engine harness to run; one of them is speed sensor for vanos and the other I forgot;

[Nick_S]

^^^ Good post. I for one never knew the temp sensor was vital to starting. Will have to go double check my connections there.

[Steven]

Yeah I have a big list and diagram of the correct wires with corresponding wire colors... So that should be all good... And it's not actually starting it'll fire for like half a second then go back to just turning over. And that's if I'm lucky..

[Wanganstyle]

Yeah I have a big list and diagram of the correct wires with corresponding wire colors... So that should be all good... And it's not actually starting it'll fire for like half a second then go back to just turning over. And that's if I'm lucky..

If you claim it fires one really obvious way to see if your claim is bs or not

Spray some brake cleaner or starting fluid inside the intake manifold and see if it will idle.

If everything is working besides fuel supply the engine will idle for 20+ seconds on a spritz of brake cleaner.

Obviously be careful; dont hurt yourself / diaf by od.

Sent from my SAMSUNG-SGH-I337 using Tapatalk

[Wanganstyle]

^^^ Good post. I for one never knew the temp sensor was vital to starting. Will have to go double check my connections there.

2 temp senders in the m50 head; both are 2 wire plugs but one has only 1 wire inside- this is the ecu ground sender for the guage cluster temp.
The other 2 wire temp sensor in head is to the dme.

If dme has no water temperature it will be angry; no start is quite possible. A toyota 2jzge with distributor will not fire if the water temp sensor to dme is unplugged

Sent from my SAMSUNG-SGH-I337 using Tapatalk

[Nick_S]

If you claim it fires one really obvious way to see if your claim is bs or not

Spray some brake cleaner or starting fluid inside the intake manifold and see if it will idle.

If everything is working besides fuel supply the engine will idle for 20+ seconds on a spritz of brake cleaner.

This is the exact position I'm in. Everything seems to be working but I'm not getting any fuel. It will fire right to life with some carb cleaner. I'll be honest and I haven't dug too much into the electrics. I bought an adapter hoping I wouldn't have to mess with it but it seems I need a better understanding of what I'm working with to make this work properly.