Anrother no spark no fuel no start thread ( after engine swap)

[Fluffee]

Actually read pinout wrong, no voltage at 24. Went through the whole check and everything is good minus no power from pin 37 power input from main relay

[Fluffee]

What does pin 24 go to? It says i should have no voltage going to that pin and i have voltage going to it so apparently that ground wire is going somewhere it shouldnt

[jlevie]

The dme is working. I checked 27 18 and 37 and none of those are getting voltage.

Did you check everything else (in order) in that list?

BTW: 12/18/37 being correct doesn't mean that the DME is running. Only that it has power.

[Fluffee]

The dme is working. I checked 27 18 and 37 and none of those are getting voltage.

[jlevie]

No spark (or fuel) when cranking usually means:

1) The DME isn't running
2) The DME isn't getting timing data from the engine

The diagnostics above will pretty much tell if there is a fault that causes those. Go through each step in the diagnostics. Go through each step and report back.

[Fluffee]

I see that on every no spark post on every bmw forum, i have checked everything and everything seems good. Has anyone had this problem and successfully fixed it by replacing something? Or maybe there is a bad ground somewhere? My car was running, then i swapped engines with a better running motor and now i am getting no spark and no fuel, I don't see how nothing has changed and everything is plugged up the same way can cause no spark to the wires.

[jlevie]

For the engine to run the following conditions must be met:

Power on DME pins:
27 Start Input
18 Un-switched Power input
37 Power Input from Main Relay

Ground on DME pins 2, 14, 19, 24

Timing data from the CPS on DME pins 47 & 48 from a rotating engine

To have spark power must be present at the coil positive and ground pulses
from the DME's pin 1 must reach the coil negative. Power to the coil is
controlled by the ignition switch via C101. When checking for spark, use the
output lead from the coil to eliminate the distributor, rotor and plug wires.

To have injector firing power must be present at each injector and ground
pulses from the DME's pin 16 (Bank1) and pin 17 (Bank2) must reach the
respective injector bank. Note that the injectors are wired as two banks of
three. With cylinder 1,3,5 being bank 1 and 2,4,6 being bank 2. Power to the
injectors is controlled by the main relay. Injector firing is best checked
with a noid light.

The fuel pump relay must have power on pin 86 (relay coil) from the main relay
output (pin 87) and power on pin 30. The DME will ground pin 85 to turn on the
relay and power the pump(s) via pin 87. Of the above, only the fuel pump power
is fused. So if the there's power at pin 87, but not at the pump, check fuse
11.

The main relay and DME pin 18 receive power from the smaller of the two wires
that connect to the battery's positive terminal. That wire incorporates an
in-line fuse. When the DME is presented with a start signal, it grounds the
main relay pin 85 and furnishes power to the fuel pump relay, injectors, and
DME.

Troubleshooting:

Disconnect the battery and the DME cable. Then:

1) Disconnect the coil negative and check continuity from that connector to
DME pin 1. Also verify that from DME pin 1 to ground is an open circuit.

2) Check the resistance across DME 47 & 48, which should be 500-560 ohms. If
the CPS is dismounted, the resistance can be seen to change from about 500 to
540-560 ohms when a ferrous object is brought to the face of the
sensor. Neither pin should be grounded.

3) Check for continuity from DME 36 to main relay 85 and from DME 3 to fuel
pump relay 85.

Reconnect the coil, remount the CPS (air gap should be 1mm), plug the
relays back in, reconnect the DME, and connect the battery. Then do the
following checks:

1) With the key off, verify that power is present at DME pin 18 and main relay
86 & 30.

2) With the key on, verify that power is present at DME pin 27 and pin
18. Power to pin 18 is from the main relay and there should be power to the
injectors and fuel pump relay.

3) With the key on, verify that no voltage is present at the DME grounds (2,
14, 19, 24).

4) Verify that power is present at the coil positive and at fuel pump relay
pin 30. Those get switched power from the ignition switch via C101.

The engine will start and run (if poorly) with only those connections to the
DME in place. The other signals from Cylinder ID, AFM, temp sensor, etc., are
necessary for proper operation. But they won't prevent the engine from firing.

IMPORTANT:

A power check means seeing a voltage within about a tenth of a volt of what
you measure across the battery terminals, which should be at least 12.6v on a
charged battery.

A continuity check means seeing less that 1 ohm of resistance.

An open circuit means seeing a resistance of at least 100k ohms.

A good quality auto-ranging digital multimeter will make these tests much
easier.

[Fluffee]

They are in right place, already checked, nothing happened.

[slammin.e28]

Are you sure you didn't mix up the cps and impulse sensors connectors? Switch those two plugs and see what happens

This. I've got the same problem with a 2.7 I built. I switched the connections, but the battery was too dead to turn the car over.

[5Toes]

Are you sure you didn't mix up the cps and impulse sensors connectors? Switch those two plugs and see what happens

[Fluffee]

I have an 88 325is and just swapped to a motor out of an 88 325i ( Heard the engine run ). I just finished to swap into my car and i am not getting any spark or fuel. I have been doing a lot of research and still haven't figured out why I cannot get my car to start. Replaced CPS so i know that isn't the problem. Used a multimeter to check to see if the coil is getting power and it is, but it isn't distributing power to the wires. Also checked the pins on the ecu and the ignition start pin is getting power, but the main relay output isn't getting any power to the ecu. What could be causing this? I've helped do the swap a couple times and i know a fairly good bit about the m20 and I am pretty sure i have hooked everything up right and have everything where it is supposed to go. Fuel pump isn't cutting on when i turn the switch on but if the motor doesn't have any spark then it will not tell the engine to engage fuel. I have been trying different stuff that i have been reading on different forums but so far everything i have tried has been a failure. I know this motor runs as i heard it before it was taken out of the donor car( guy pulled motor for m52 swap.) so i know that there is nothing wrong with the motor, it has to be something wrong with my wiring/ecu/ or some ground that i haven't plugged up somewhere, i just need some insight to my problem as i really need to have my car to get back and forth from work.