330i ECU Replacement?

[clarko74]

Morning all,

My 330i is playing up and it might be the ecu, (the garage that is looking at it having to call in a BMW technician to look at it with BMW diagnostic equipment as they can't find the fault themselves).

If it is the ecu what is the easiest way to replace it? the options seem to be:

• Replace the ecu, ews, keys and locks
• Replace the ecu and sync it to my cars current system
• Replace the ecu and disable the ews

Looking at these I would have thought that syncing a replacement ecu is going to be the simplest, is this the case? And how/who can do this?

Cheers,

[martauto]

Morning all,

My 330i is playing up and it might be the ecu, (the garage that is looking at it having to call in a BMW technician to look at it with BMW diagnostic equipment as they can't find the fault themselves).

If it is the ecu what is the easiest way to replace it? the options seem to be:

• Replace the ecu, ews, keys and locks
• Replace the ecu and sync it to my cars current system
• Replace the ecu and disable the ews

Looking at these I would have thought that syncing a replacement ecu is going to be the simplest, is this the case? And how/who can do this?

Cheers,

What are the symtems that are playing up as both me and the lad have 330i`s?

Mart.

[clarko74]

I was driving to work the other day and it just went really sluggish, lots of lights on the dash, then a flashing engine light. So I pulled over and turned the engine off, from then it wouldn't start any more. The RAC man read the faults and said it was something to do with cylinder 2, probably the fuel injector.

Had it towed to my mate's garage, they confirmed it was the fuel injector, they replaced that but it was still running very roughly. They have investigated further but haven't found the source of the issue. They did say that the voltage to the injectors wasn't what it should be which is why they are suspecting the ecu.

They know a bmw tech who does a bit of freelance work for them so they are going to get him round to have a look at it.

Any ideas?

[martauto]

I had a few questions fired at me over something else but may be of value,
How old and good is the battery and also the altenator ?.
Engine earth leads ?
I know these sound stupid questions to ask , but DC moves in mysterious ways so to speak and unless the "heart" of the beast is pumping as it should .....?
I`ve just not heard of ecu failure to give these issues.

Mart.

[clarko74]

To be honest, I didn't ask them about the battery, alternator, etc. As a professional garage I would hope that they would check that sort of thing.

Turns out it was ecu related, not quite sure exactly what was the issue but the bmw chap had a look at it and there was an update available for the ecu. He updated that and it fixed it.

[martauto]

Happy days !!!

Mart.

[clarko74]

It was happy days, for three days, until exactly the same fault happened again, I was just round the corner from home so managed to coax it gently back to mine. My E30 was moted last week so I have been using that and the E46 has just sat there, but I thought I should investigate so last night had a poke around and discovered this:





Doesn't look great does it? I'm surprised it was working at all. I looked up which pin is for the injector signal to cylinder 2 and it is pin 34, which is where the big brown blob is in the middle on the third row down. So I think this is likely to be the cause of my problems.

The thing now is how to fix it. I can obviously clean/dry the plug and socket but I need to find where the water is coming from and prevent it getting there. The ecu enclosure was well sealed and apart from that particular plug/socket was completely dry, therefore I think there must be a leak into one of the cables (possibly the one to pin 34) and the water is being drawn along the inside of the cable by capillary action.

It's going to be fun trying to find that...

[clarko74]

Having done a bit of research it appears that a dodgy thermostat can force coolant into the wiring loom which can than make its way up to the ecu. I have a new thermostat to put in anyway so I'm going to try that to see if it has any effect.

[clarko74]

It took me a while to find a full pin assignments list for the E46 ecu so here it is for information:

Clicky

[clarko74]

It would appear upon closer inspection that pin 34 is no longer present, not good.

[maxfield]

I didn’t notice this thread until now. I have seen this once before on an E46.

I was lucky and cleaned all the connections up, I put a new thermostat in. I also put a bit of solder in the wiring to stop it back tracking to the ECU, if it ever became and issue in the future.

[clarko74]

I managed to get the broken pin out of the plug which was a relief.

I've got myself a secondhand ecu, ews and key, my plan was to replace these, which I have done, but it's not working. I took my old key apart and took the electronics out of it, I've replaced the ecu and ews and tried to start the car with the old key and the new one right next to it. I'm getting dash lights but nothing at all when I try to start the engine, which seems to me like the immobiliser is immobilising it. Should this work? Or is there something else I need to do? Or despite what I have been told will this never work?

[pianist]

So did you try your old ecu is it dead?

[clarko74]

It probably works but is missing the pin for the signal to injector 2. I've not tried to fix it as repairing the pin will mean replacing the whole ecu socket which is probably soldered to the circuit board. I did wonder about taking a new wire from the ecu to the loom but thought a working ecu would be easier.

Apparently the circuit board for the key has to actually be inside the key for it to work (rather than just near it), there must be a connection between the circuit board a metal of the key itself. I will be trying this tonight.

[clarko74]

Bit of an update on this:

I got myself a replacement secondhand ecu, ews and key. While it worked and the misfire was gone, it wasn't happy. It took longer to start, previously it would start immediately after only a second of cranking but now it was taking much longer to start. Then after a minute or so of running it threw out a load of new fault codes, to do with map sensors, O2 sensors and the like. The replacement ecu, while being from a manual 330i did not have the same part number as my original one, I think it must have been an earlier or later ecu that wasn't happy with the other older or newer parts in my car.

By this time I had got my E30 moted so had started using that as my daily while I worked out how to fix the E46, so it sat there for a few weeks getting covered in pigeon poo. My E30 however does not have air con and as I'm going away this weekend I started thinking about trying to get it running again earlier this week.

I thought up a plan to fix it. I was pretty sure that the only problem with my original ecu was that it had a broken pin. I also remembered that when I was looking at the pin designations for the ECU sockets/plugs that there were a few pins that are not used. So decided to take my ecu apart to see if it was possible to rewire it as I knew from removing the broken pin from the plug that relocating one of the wires in the plug was relatively simple.

So I soldered a wire from the contact of pin 32 (the broken one), then found an unused one, pin 50, on the top row of the socket (as it was easy to access) and soldered the wire to this.

[/url]

[/url]

I could have soldered the wire to the contact on the bottom of the PCB for pin 50 but it was easier to solder it onto the relatively large wire from the socket to the PCB. And there was a handy hole in the PCB that the wire could pass through.

All I then had to do was relocate the wire in the plug from 32 to 50 and of course put the original ews back in and the chip in the key. And it worked! It's running nice and smoothly, no misfire and no fault codes.

[martauto]

Great fix, pleased for you.

Mart.