2.7 stroker build no start

[SkywayScraper]

Just finished my 2.7 conversion and now I have a no start. I believe all of my connections are right, but could be mistaken. Does anyone have any tips on what could be causing no power to the engine? I have been following this site http://www.strictlyeta.net/technical/328i_6.html .

[acolella76]

Does it turn over? Are you getting fuel or spark? All of your power/grounds are hooked up (starter, alternator, battery posts, battery,etc.)?

[MR 325]

You say no start but then you mention no power, which one is it?

Is it cranking? Is it getting fuel? Is it getting spark? Is this Motronic 1.3?

[Madinthe717]

did you swap the two plugs next to the intake manifold, one comes from the wires the other is from the crank pully

[SkywayScraper]

No power to even try an turn it over I have 1.3 motronic with 173 ecu. The wiring harness I got had a cut plug that runs to the fuse box I think its the c101 or c103. The crank positioning sensor and the plug for the ignition loom are right. It has no spark no fuel so I'm not getting power from somewhere. All the power and grounds are hooked up right.

I think the plug to the fuse box is wrong. If the plug from the fuse box is wired wrong to the harness will that cause no power? Also all my interior lights and dash work.

[jlevie]

If C101 has been cut off the engine harness, that will have to be replaced before the engine will run. Otherwise work through what is below to find the cause.


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.

[MR 325]

So the whole car has no power? Check your main power cable connection to the starter, the battery terminal on the firewall, and the actual battery.

[SkywayScraper]

Whole car as in just the engine bay has no power. Is there a picture just to clarify what is the positive and negative on the battery terminal on the firewall. My starter only has two connections unlike the picture of the starter in the link. I am pretty sure it is hooked up right. It has to be that c103 plug because I rewired just the wires that match up to colors. I have 4 wires left over that would not match up to about 8 wires from the harness.

[SkywayScraper]

i got it to turn over, but i have no fuel. i had to pull my main relay because when i turned the key on to accessories smoked started to come out of the white relay wires. the wire that was smoking was red with a yellow stripe. does anyone know what that goes to?

[yert315]

If I were you, I would start over and get an uncut wire harness. It will eliminate the possibility of a bad/wrong splice. Then go from there.

[jlevie]

If you saw smoke from the wires leading to the main relay socket the engine harness is probably toast and you need another engine harness. Apparently you attempted to use a harness for an 9/87 or later M20B25 on a car built before that date. The difference is that early cars have a wire (pin 20 from memory) in C101 grounded and late cars use that for some other purpose. The best fix is to cut the wire on the body side of C101.

[SkywayScraper]

I now have fuel coming out from following that other thread about the c101 and c104 in the glove box. I am still getting smoke when the white relay is plugged in and no smoke when its out. The wire that is smoking is red with a yellow strip does anyone know where that goes, I believe it is being grounded out that is causing it to smoke? The engine harness is from an 89 I and the car is an 87 e.

[jlevie]

I now have fuel coming out from following that other thread about the c101 and c104 in the glove box. I am still getting smoke when the white relay is plugged in and no smoke when its out. The wire that is smoking is red with a yellow strip does anyone know where that goes, I believe it is being grounded out that is causing it to smoke? The engine harness is from an 89 I and the car is an 87 e.

See my previous post.

[SkywayScraper]

jlevie I just cut that brown wire on the body harness in slot 20 on the c101 but still no crank I think that relay is toast. If it was ground out would that cause it to burnout and jsut need to be replaced?

[jlevie]

Being grounded could damage the relay. Start at the top and run through the diagnostics I posted earlier and you will find out why the engine isn't starting.