m30 running rough (NOW WITH VIDEO)

[tfritz]

^thanks! I'll check all that tomorrow

[csermonet47]

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.

Try this to make sure all the harness stuff is correct.

Here is the DME pinout: https://docs.google.com/file/d/0B97_...zg3/edit?hl=en

[yert315]

I had a similar issue when I used the m20 harness. Never fully figured it out. However, I swapped over to the b35 harness and it ran like a champ.

[Grand525]

One of the injector harness is not fully connected?

[ttrousdell]

I ran with no o2 for a month in my e30 m30b35 and used the m20b25 harness and it ran without a hickup. If its not intake leaks I would suspect that youre getting a wrong signal to the ecu because of a faulty maf, tps, etc.
My brake booster set up...

[tfritz]

^Yeah i figured that out, i was just stumped since this motor came out of my bro's e34....that is the least of my worries now tho, I need this thing to run right!

[mini612]

tfritz, I'm currently doing the same swap but with b34. I also couldn't find a place to hook up the Brake Booster hose and was told I have to tap it to the intake mani.

[tfritz]

Corrected my vacuum lines and it still runs the same. While running I unplugged the tps, ran the same. Also while running I unplugged the miller maf sensor, and there was no change...

[tfritz]

after searching on here all evening, i believe I have one of the vacuum lines on wrong.
Also wondering where to hook up the brake booster hose??...

[tfritz]

Needs throttle to start, will run while barely on throttle, if more throttle is given it surges...

[tfritz]

Okay, so I did find a small vacuum hose unhooked (went to charcoal canister), and tighten the grounds and sanded some paint off the ground on the motor mount. It still runs like crap and surges. There is no alternator hooked up and some of the injectors are turned so the shorter wires on the m20 harness would reach ( i dont know if that affects anything). Currently trying to get a video of it running to load..

[tfritz]

I will double check my grounds and vacuum

[csermonet47]

Your grounds should be fine then. Did you sand paint off the mount so it is metal to metal? O2 sensor would only cause it to run closed loop and a bit on the rich side. I would double and triple check vacuum.

[tfritz]

Which grounds? The engine is grounded with a new cable from motor mount to body. Im pretty sure the harness ground is secured but I will make sure tomorrow. Should no o2 sensor cause anything like this?

[csermonet47]

It does sound a bit like vacuum. Maybe check your grounds too?