Early 325i Still a non starter, losing the will to live now!

[mattmk1]

I have an early pre facelift 325i that started fine around ten days ago, however when i went to pull away the engine stalled and since then has refused to restart.

The fuel pump wasnt running and there was no spark. A few tests showed one of the crank sensors (the rpm speed sensor) was showing an open circuit so this was replaced, and still the same fault (no spark or fuel).

Whipped the sensors out and checked the timing pin is still in the flywheel - it is, and someone has welded the sod in, so thats o.k.

I linked out the fuel pump relay, but still no life in the fuel pump. However after a few days of head scratching i found a 50amp inline fuse running from the battery positive was blown.

Replaced the fuse, and now the fuel pump runs as it should. Got fuel at the rail etc whilst cranking.


However, still have no spark and no injection of fuel. Have 12v at the coil (both sides + & - ), but no spark from the centre. Have 12v down both terminals of the injector plugs (ie its not being pulsed to earth).

The ECU in the car was recently re manufactured by ATP, but i got another known working ECU from a fellow member but the symptoms are the same!


Any ideas? Desperate for the car now as need it for work!!


Cheers
Matt

[Brianmoooore]

You won't detect pulses at the injectors with a meter at cranking speed - they're too short.
Any idea what blew the 50A fuse?
If the fuel pump runs when the engine is cranked, most things are working. The ECU is largely powered up, is seeing pulses from the CPS, and is integrating them to drive the pump relay.
Have you tried a fresh DME relay, or linked together pin 30 and both 87's?
Are both crank sensors good?

[mattmk1]

The fuse insulation sheath had rubbed through on the side of the boot floor, touched it to earth and im assuming that is what has popped the fuse.

Ok cheers, i thought you would see the injector pulse via test light but thanks for putting me right!

Both crank sensors are good, ive been told it will run with a faulty speed sensor, but not with a knackered TDC sensor. So it may have been running for a good few months with the broken speed sensor in.

The TDC sensor shows 970 ohms and the new speed sensor shows 910 ohms resistance. Iv tried swapping the two sensors over/interchanging them and still have exactly the same symptons.

DME Relay? where abouts is that? I have two relays under a black plastic cover on n/s inner front wing, one is the fuel pump relay and the other is a white BMW relay (4pin). Iv took the cover off the top of the white relay and when you turn the ignition on you can see the relay make contact??

Is this the DME one that you refer to?

Many thanks so far Brian!

[zaust]

That is the dme relay.

Back to basics fella. Start the hunt for spark (or not) Might be coil, lead.

[mattmk1]

Any more ideas on this ? Seems the coil negative is going straight to earth, have power at the coil positive, ICV is buzzing and fuel pump is running. Also still have no injector pulse (checked with test light)

Thanks so far.

[Brianmoooore]

What makes you think the coil neg. is going straight to earth? If it is, you will have a very hot coil.

[mattmk1]

I thought the ECU dropped the coil neg to earth to generate a spark, and i was getting 12v at both sides of the coil as if the current was flowing straight through it, ie the ECU was always earthing the coil. In my mind it made sense, but Ill admit i know nothing of coils etc other than that they work by some form of witchcraft.

Turns out that the ECU i bought off here was a dud, got another one and after repairing the blown 50amp fuse in the boot she fired straight away.

In Summary: The blown fuse was my initial problem and cause of non starting, the crank sensor was a fault find but wasn't influencing the 'will not start', i then assumed a dodgy ECU so bought one off here, fitted it, no joy. Then found the blown inline fuse, repaired it, still no starting. After head scratching i tried another ECU and she fired straight away.

Combination of problems really but she runs now.

Thanks for all the advice/ ideas, much appreciated.

[Brianmoooore]

If the ECU was earthing the coil negative, there would be 0 volts on that terminal, not 12.
You are quite correct that the 12 volts on the negative terminal is the voltage that's on the + terminal "flowing straight through".
You are unlucky to buy a duff ECU. They are normally very reliable.

[Nay]

Turns out that the ECU i bought off here was a dud, got another one and after repairing the blown 50amp fuse in the boot she fired straight away.

Where's this 50amp fuse? I have the same problem and am looking for any possible solution as it's driving me nuts.

[Brianmoooore]

Within a few inches of any rear mounted E30 battery.

[TOMMYSPANNER]

had same problem on my 87 pre face lift chromie 325i, this forum stopped me tearing what little hair i have out !