2000 E46 318i (M43 engine) - 6v @ injectors & AFM / no start

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Thread: 2000 E46 318i (M43 engine) - 6v @ injectors & AFM / no start

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  1. 2000 E46 318i (M43 engine) - 6v @ injectors & AFM / no start 
    #1
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    AJ80's Car Details
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    Hi there, I wonder if anyone could help me with this one.

    I've recently had to replace the head gasket on my fathers 318 due to failure of one of the grotty plastic water pipes, now I seem to be getting some electrical issues after putting it back together Not sure what's gone wrong (or even how, with the ECU disconnected during the job) and would really appreciate any advice anyone can give - it's driving me crazy

    Symptoms:
    It had codes for crank and cam sensor pre-rebuild, so they've been replaced.
    Car won't start - timing, compression etc are all spot on, engine turns over on starter but no spark or injection
    Seem to be getting voltages of around 6v at the airflow meter and injector power feeds checking them with a multimeter. Doesn't sound quite right, but I don't work on BMWs generally and don't know if that's normal.
    Inpa gives error codes for DISA, fuel tank vent, secondary air and AFM. Other than AFM would any of these actually stop the car starting?

    Diagnostics are confirming the car's getting 12v into the ECU no issues, voltage on the AFM connector stays around 6 volts even when you go down the motor disconnecting each component to see if any of them is causing a voltage drop (I've run out of things to disconnect from the engine and no improvement as yet). Have I somehow exploded something internal to the ECU, or am I chasing a problem that isn't actually there due to inexperience with this motor?

    Many thanks in advance
    Alun J
     
     

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    #2
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    jcjdavis1's Car Details
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    Hi. You have not mentioned the fuel pump, is it getting power, pumping? Jim
    The older I get the wrong bit gets stiff !!
     
     

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    #3
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    AJ80's Car Details
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    Hi Jim, thanks for your reply

    I thought the fuel pump was working ok, as there's been fuel pressurised in the rail the last couple of times I've taken it apart to check (albeit usually after many attempts at starting it). It seems I was wrong. I've checked again today and found that whilst it's getting 12 volts to the connector with the key turned to run or while cranking it seems to be running very, very quietly? Fuel rail pressure after the pumps been running 10-15 seconds is negligible, just a spit from the pressure test valve.

    Fuel pump fuse was ok when I checked it, but I'll drop in a replacement just to be sure when I get back to it tomorrow. Maybe worth supplying the pump with 12v directly to make sure it's working properly on a good power feed? If it works it'd be kind've a relief as it'd suggest I've just messed up a power feed or earth somewhere.

    Thanks again, Alun
     
     

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    #4
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    AJ80's Car Details
    Model of Car:
    318i
    Year of Manufacture:
    2000
    Transmission Type:
    Manual
    Car Body Type:
    Coupe

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    Location
    Newport
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    Finally got the time to get another look at it. Pump goes nicely with direct application of 12v. AFM & other components are still only gettting just below 6 volts. All 5 wires of the AFM wiring from the connector are terminated at the ECU and have continuity though the loom. My thinking at this point is this: if the wiring is ok, the power to the ECU is ok (Inpa shows ECU voltage of just over 12volts), and the power feeds coming out of the ECU are not ok that very very much suggests a toasted ECU to me. I've run out of other things to check.

    What do you reckon? There appear to be no wiring diagrams for this motor anywhere, not in the haynes or bentley manuals (expensive wastes of time), so unsure at this point if there's actually anything else worth checking or if it's time to go replacement ECU hunting (well, ECU and pile of related bits anyway).

    edit: pulled the DME this afternoon and out of interest opened it up to see if anything was glaringly damaged. Burn marks on the inside of the casing and blown PCB traces around pin 8 and 9 of the rearmost connector (looking from the front of the car), looks like replacement time. Thanks for the help all
    Last edited by AJ80; 15-06-2011 at 17:04.
     
     

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