Edit: got fuel now but no spark! help!

[dougie30]

ok so iv narrowed my problems down to the starter, the crank position sensor, and a plug that comes off my spark plug wiring.

1) starter. i have done a bunch of searching and looking through pics and im pretty sure i have everything hooked up correctly. it is a early (86 325e) starter, bolted to my single mass 1987 325i engine/fly wheel.

i have the main power cable from the battery distribution block connected to my starter on the large lug. then i have the thick red wire from my engine harness connected to the same lug. finally i have the black and yellow wire from right near the thick red wire plugged to the bottom tab of my starter. like so

and yes my large engine ground is grounded!

2) crank position sensor. this is pretty confusing. to make it simple WHERE DOES IT PLUG INTO?? it is a three prong plug that it needs to mate with and i have 2 on the engine harness. one branching from where my icv plug is and one branching from the little vacuum hose that goes to under my throttle ( looks like a J). i tryed both and nothing. pics would be great for this one

3) plug from spark plug harness. pretty simple, it comes from where all the plugs go onto my distributor. it is long and is also a three pronged plug, i just have no idea where it goes.


and on top of this all i have 2 plugs that are on my tranny ( i think one is a speed sensor or fly wheel sensor?) i have no place for these to go on my wiring harness.


i know its alot to read and understand but i just want my car to start :(

thanks guys

[dougie30]

found out that the two plugs coming from my tranny are the crank position sensors for the 325e, i didnt know they changes the sensor to the front of the engine for the 325 i.

does this mean i can ignore the sensors on the trans?

[jlevie]

The sensors in the bell housing are not needed with an M20B25 engine. There will be two 3 pin connectors that branch off the engine harness a bit forward of the middle of the engine. One goes to the CPS and the other goes to the Cylinder ID sensor that comes from the #6 plug wire.

[dougie30]

thanks jlevie, i couldnt find out where they went for the life of me.

but i did get it to crank, turned out it was a bad starter ground to the battery.

but my new problem is i have no fuel so im going to figure out if my fuel pump is bad or not today.

[jlevie]

The fuel pump only runs when the DME sees timing data from a rotating engine. So the first tasks are to ensure that the DME is running and that timing data from the CPS reaches the DME. Work through what follows.


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.

[dougie30]

OK I have more info.

I only have power to pin 18,13 and very weak signal on pin 24 on DME plug. I have full power to all fuses and relays. I do have spark to coil. I don't have continuity to pin 1.

so im getting full power then stops at the dme side of my harness, except the pins i said above.


Also here are some pics of a few plugs I don't know where they go. The two little female ones are right near the fuse box the others are right near DME plug

Also checked the cps has 545 omes. And fuse 11 has no power.

[dougie30]

More info and bump because Im desperate!

OK broke out the volt meter again and started checking my dme plug, here is what I found with key on:
#13
#18 are the only two with power.

#19
#14
#2
#24
#52
#55 all are grounded

Also found out #11 fuse is grounded? Though it was supposed to have power for the fuel pump?

Please give me some info!!!!

[mr.vang]

If it has spark most likely the cps is good. I bet your external pump is bad.

[dougie30]

Well my car did sit for 8 months so would it be likely that the pump would go bad? And would it make any noise?

edit: ecu and icv both have power because icv vibrates and euc makes noise but fuel pumps are quite.

how can i test them before i go out and buy new ones???

[dougie30]

Moar info!

OK so I jumped my fuel relay and fuel shot out of the line.. So my pumps do work!

Buttt now I have no spark. It has to do with the coil. I checked continuity between the ppower and ground to the pins #1 and #2 on the ecu pins.

Now this is where it gets weird. The power is coming from the " ground" wire and the usual power wire... And now there is no ground? So in turn no spark. I checked this like 5 times and idk why it is doing this. I have continuity from both to my ecu pins so now I'm stumped.

Also there is no resistance from pin 47-48? What does this mean?

Anyone feel free to give me some ideas

[jlevie]

I doesn't sound like you are using the diagnostic list the right way. Follow the trouble shooting steps one at a time. If you don't get the right results on a step you can't move on until that has been resolved.

[dougie30]

ok the step im stuck on in the resistance between pin 47 and 48 what could be causing this?

[dougie30]

checked a few more things today. my cps i pulled off and tested with a magnet to see if it still worked, the ohms jumpped from like 350~to750~ so im assuming it is reading data but now that i pulled it off the aluminum bracket holding it on stripped so now i need a new one of those.

i also checked for the continuity of my pins after i checked my cps and pin 47 and 48 now have continuity. so im back to square one again.

any more info would be great.

[Chriskbmx]

my question is, is this a swap car? im assuming you went from an e car to an i motor? i assume this because the transmission you are using is from an e car. please clarify.

[dougie30]

yes i swapped in a 87 325 i engine in to my 86 325e.

i was checking power to the dme pins and found out i have no power to pin 37 coming from main relay.

any reasons why this might be?

i tried a different relay still same thing. and yes i checked my cps about 38649864873 times.