944 s2 weird electrical fault - any thoughts ?
Discussion
Hi
odd one - and excuse my ignorance - one injector not getting the wrong signal and engine not running, runs on 3 not 4....any 3 ! Its not the ecu which apparently sends 1 signal only so wouldnt have 3 working alone (and sent it off to be checked - negative for fault)
dodgy earth ?
any advice gratefully received - pls excuse brevity, also dodgy computer keyboard..bad week
Thanks Gary
odd one - and excuse my ignorance - one injector not getting the wrong signal and engine not running, runs on 3 not 4....any 3 ! Its not the ecu which apparently sends 1 signal only so wouldnt have 3 working alone (and sent it off to be checked - negative for fault)
dodgy earth ?
any advice gratefully received - pls excuse brevity, also dodgy computer keyboard..bad week
Thanks Gary
I think I understand.... question is whether it is always the same cylinder that isn't firing? I get the impression that you have been swapping injector leads about and think you may have one of the 4 injectors dead.
Personally I would look on ignition side first - leads and plugs. Establish which cylinder isn't firing and if the non-firing is portable to another cylinder (by swapping plug leads etc.). Once I knew all the ignition side was functioning correctly I would move to fuel side and establish whether there was a portable fault in the fuel side which would allow it to be narrowed down and the offending part swapped out. I would always try and rule out the ignition side through diligent assessment and fault finding before moving on to the next thing.
Personally I would look on ignition side first - leads and plugs. Establish which cylinder isn't firing and if the non-firing is portable to another cylinder (by swapping plug leads etc.). Once I knew all the ignition side was functioning correctly I would move to fuel side and establish whether there was a portable fault in the fuel side which would allow it to be narrowed down and the offending part swapped out. I would always try and rule out the ignition side through diligent assessment and fault finding before moving on to the next thing.
The DME is the ECU. The series one injectors are different to series two (series one has a 924 style dash and series two has an oval dash, nothing to do with S2). The DME and air flow meter must match.
I dont have the information to hand but Im sure that youll be able to find it with a little searching. Its usual to see the Bosch and the Porsche part numbers and one AFM usually does a far larger range of vehicles than the DMEs do.
Where people dont know better then early and late parts may have been mixed as they all look the same and fit.
I dont have the information to hand but Im sure that youll be able to find it with a little searching. Its usual to see the Bosch and the Porsche part numbers and one AFM usually does a far larger range of vehicles than the DMEs do.
Where people dont know better then early and late parts may have been mixed as they all look the same and fit.
Get them to check the fuel pressure; chances are the fuel pressure regulator has failed giving TOO MUCH fuel pressure which is overloading the DME drivers, disconnecting one injector lowers the current requirement and allows the DME to keep the remaining injectors operational.
Ideal fuel pressure should be approx 5 bar
Ideal fuel pressure should be approx 5 bar
The common fault of failed fuel regulator (which may or may not be the op's problem) does not overload the injector drivers. The current draw is not increased as pressure increases, this is internet bunkum.
part of the official porsche testing procedure does include disconnecting one of the injectors, this is to lower the afr to a manageable level for the o2 sensor.
part of the official porsche testing procedure does include disconnecting one of the injectors, this is to lower the afr to a manageable level for the o2 sensor.
Thanks for that. I was quoting from experience rather than just bandying about bunkum as you suggest. A 924S in with us that had the self same issue yesterday (which is now sorted) displayed 10 bar plus rail pressure - when measured with the fuel pump manually switched, the injector pulse could be seen switching off as the pressure peaked at approx 10 bar, once the fpr was replaced the rail pressure returned to its expected 5 bar and the engine runs well. I suppose we'll have to wait and see how the OP's car fares.
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