Disaster! Spare MBE 975B ecu!?!

[g0gs]

Hi all

Having a bit of a nightmare. Bought my M12 a few months back and had an absolute blast in it until one day driving home the car died.

To cut a long story short the 80amp fuse had blown. Changed the fuse and tried to start the car however the injectors were constantly being held open and flooded the engine. I put the car into an auto electricians in Aberdeen, they diagnosed the fault as the ecu. I ordered the LAST ecu from the factory (£1030)all set up for my car. They fitted the ecu and started the car which blew the 80amp fuse and fried the brand new ecu!!! They were told to investigate the alternator which they seem to have ignored and proceeded to start the car. They have now removed the alternator and found it to be significantly overcharging. I could have the alternator changed and hope the ecu has survived but that seems unlikely?

I have spoken to the guys at Jetstream who have been a great help, can't thank them enough for their time and patience. In hindsight I should have had the car transported down there but I'm stuck for now.

Does anyone out there have a spare MBE 975B ecu they are willing to part with? Or know where I might source one? I have spoken to MBE and they couldn't help! Its for 2.5 m12 by the way.

Thanks any help appreciated

[Nickellese]

I feel your pain and wish I could help.

Misfire gremlins have infected my car and was told that no more ecu's existed. Mine was sent back to MBE for diagnosis howvever, would this be an option for you?

[5paulmv]

Speak to graham gc1 this sounds familiar story :-(

[g0gs]

Hi Nick did you have any luck with MBE repairing yours? I have been told there's a high chance it will be wrecked but might be worth a shot sending it back.

[anonymous-user]

Fixing the ecu probably isn't that hard! Chances are, the output switches for the injectors have died. Depending on the input topography of the power supply section, the rest of the ecu could well have survived without issue (most regulators used in automotive devices can withstand "automotive load dump" voltages practically continuously, but the output switches almost certainly can't. Production cars have overvoltage protection built into their control units, but the 975 may not have this).

[GC1]

G..hope info has been of use to you,just shout if you need any more....GC.

[g0gs]

Thanks for your time Graham. Wish I had spoken to you before going the mbe route! Will see how I get on with mbe and look into emerald.

Max_torque when the ecu was replaced the car started normally untill the fuse blew, would that indicate the injectors were functioning as normal?

[anonymous-user]

If the engine was running normally, then yes, the ecu must have been ok at that point!

I doubt that ecu has a current limit on the injector drivers, they will just be dumb on/off switches. If Vbatt was excessively elevated for any period of time, chances are that the drivers could have overheated and failed - typically they fail shorted to ground, hence the injectors are open as soon as the key is turned on etc.

A visual inspection of the insides of the ecu could possibly show up thermal damage etc to those devices and associated pcb tracks.

[Adrian W]

I wonder what the difference is

http://www.pistonheads.com/classifieds/motorsport/...

[g0gs]

Thanks Adrian will have a look into that and what's required although I'd rather a 975B so its just plug and play. So annoyed its come to this, looking into Jetstream's mbe upgrade...poss send the loom down to them...still undecided.

[anonymous-user]

Is the ECU definitely fubar'd ??

[g0gs]

I'm not to sure how to tell apart from sending it back to MBE? I have spoken with them a couple of times but they said if the alternator has surged there's a very high chance it won't be salvageable.

Any suggestions? Was thinking of fitting a new alternator and trying the car but from what I've heard there's such a high chance the ecu is duff. Also I'm in 2 minds whether to cut my losses with the garage its currently in and have it transported to Jetstream for them to sort it properly. Or to sell the car in its current state to someone willing to sort the issues themselves, I have no electrical knowledge! Could be time to learn but I'm about to start a 7 week course which will really need all my attention. Just to much on to properly focus on the car at the minute.

[anonymous-user]

OK, assuming that the issue is most likely to be with the injector drivers shorting directly to earth (because it seems that is what happened last time)

1: Find the six two pin electrical plugs that fit onto the fuel injectors, disconnect any two of them (which ever are easiest to get to)
2: using a multimeter set to "resistance or continuity mode (i.e. beeps when probes are connected together) pinout these two plugs as follows:
a) find the pins that are common to each injector, probably pin1, this is the power feed from the battery when the ignition is switched on
b) the remaining pin is used by the ecu to "pull to ground" to allow power to flow through the injector at the correct moment. With the ignition switched off, this pin should NOT be connected to ground. i.e. placing one multimeter probe onto the metal of the engine (chassis earth) and one into the pin of the connector (probably pin2) they should NOT be connected. if they are, it suggests the drivers in the ECU have shorted like before.

[anonymous-user]

BTW: someone on here will probably know if the coms connector is accessable on this ecu/loom, if it is, you should be able to "talk" to the ecu with EasiMap software?? That would tell you if it is booting up and running correctly.

(Actually, i think on boot up the MBE ecus send out a pre-emptive Handshake message on the coms bus anyway, which you could easily read?)

[Gadgeroonie]

Is the old ecu up for grabs ? I want an old ecu to make a loom adaptor

[g0gs]

Thanks for taking the time to explain that, hopefully I will get a chance to digest it and have a crack. Working 12 hour shifts this weekend and with the garage the car is in only being open untill midday Saturday its not likely to be this weekend.

Gadgeroonie once the car is sorted and I have time I will email you.

Thanks

Thanks

[Gadgeroonie]