Dead car - ignition problems too??
Discussion
Got the car out the garage, started first time as usual. Left it running for a few mins and then it just died! Started again and ran for another short while and died again, now nothing ever since!!
Had the RAC out this morning for over an hour with much scratching of heads
Basically there is no spark. Coil checked ok, ignition module checked, leads checked etc etc.
Also then found no pulse on the fuel injectors. Had a look through the Bible and the only link between this system and the ignition seems to be through the ECU. Therefore I assume without the ignition present, the fuel injectors will not pulse anyway??
If it was an immoboliser problem I would guess the supply to the coil would not be seen and the fuel pump wouldn't prime.
RAC guy said may be the pick-up coil in the distributer but this seemed ok, it is only if it is breaking down under load which is difficult to test.
Any ideas gratefully received???
Cheers
Mark
Presumably either you or the RAC man checked that you haven't run out of petrol 
?
The fuel pump is priming when the ignition is turned on?
Try undoing the petrol filler cap - is there a big in-rush of air? If so maybe the tank isn't venting and you had a vacuum that the fuel pump couldn't work against. If that was it, by releasing the vacuum, it should start.
Doesn't sound like an electric fault if it ran OK then stopped, then started and stopped again. Sounds more like a fuel supply problem.
Good luck
Hutch
? The fuel pump is priming when the ignition is turned on?
Try undoing the petrol filler cap - is there a big in-rush of air? If so maybe the tank isn't venting and you had a vacuum that the fuel pump couldn't work against. If that was it, by releasing the vacuum, it should start.
Doesn't sound like an electric fault if it ran OK then stopped, then started and stopped again. Sounds more like a fuel supply problem.
Good luck
Hutch
, that was my first assumption but there was definitely no spark and no injection pulse. Assume the RAC guy tried to diagnose it, so he will have tried the usual tests. I doubt my DIY fault diagnosis is going to solve a problem stumped a professional. But for what its worth, my first steps would be:
Check you have 12v to the 12v side of the coil.
Disconnect the plug to the ignition module and briefly earth the 0v terminal. (You can tell which is the 0v terminal by checking the wire colour coding at the coil.) This should produce a spark. The best way to show the spark is with a passive strobe timing light in series with the king lead. If you don't get a spark, double check by putting the strobe between the king lead and ground (i.e. bypassing the distributor etc).
If you get a spark, the problem is in the area of the inductive sensor or ignition module. The ignition module should produce pulses of open circuit/earth as you crank the engine. The inductive sensor should produce 5v pulses as you crank the engine. If these both seem OK, disconnect the plug to the ignition module and measure the resistance to ground of the 0v terminal in the plug (ignition off). This should normally be connected to the 0v side of the coil (which supplies 12v to it), earthed via the ignition module and tapped by the ECU and tacho. When disconnected, you should see a high resistance to ground. If the ECU, tacho or a wiring fault are holding this low, you won't see a spark despite all the components checking out OK.
Assuming you manage to get a good spark at the coil, then follow it through and check that it is reaching the plugs.
Don't forget you may have multiple faults so fault finding by substitution is not reliable.
Once you get a good spark, you will have separate problem to get the engine fired up. It will almost certainly be flooded by now and you will probably need to change the plugs.
At this point you may find the ignition wasn't the only problem. Keep an eye out for any other unusual behaviour - you should hear the fuel pump priming when you switch on, see the tacho reading while cranking etc.
Good luck and I hope this gets you closer to the problem. I'm sure you'll track it down eventually.
BTW if you're definitely got an ignition problem, you may want to disconnect the fuel pump while you investigate it. Make absolutely sure you remember to reconnect it afterwards though! And keep the battery charged up.
Cheers,
Peter Humphries (and a green V8S)
Check you have 12v to the 12v side of the coil.
Disconnect the plug to the ignition module and briefly earth the 0v terminal. (You can tell which is the 0v terminal by checking the wire colour coding at the coil.) This should produce a spark. The best way to show the spark is with a passive strobe timing light in series with the king lead. If you don't get a spark, double check by putting the strobe between the king lead and ground (i.e. bypassing the distributor etc).
If you get a spark, the problem is in the area of the inductive sensor or ignition module. The ignition module should produce pulses of open circuit/earth as you crank the engine. The inductive sensor should produce 5v pulses as you crank the engine. If these both seem OK, disconnect the plug to the ignition module and measure the resistance to ground of the 0v terminal in the plug (ignition off). This should normally be connected to the 0v side of the coil (which supplies 12v to it), earthed via the ignition module and tapped by the ECU and tacho. When disconnected, you should see a high resistance to ground. If the ECU, tacho or a wiring fault are holding this low, you won't see a spark despite all the components checking out OK.
Assuming you manage to get a good spark at the coil, then follow it through and check that it is reaching the plugs.
Don't forget you may have multiple faults so fault finding by substitution is not reliable.
Once you get a good spark, you will have separate problem to get the engine fired up. It will almost certainly be flooded by now and you will probably need to change the plugs.
At this point you may find the ignition wasn't the only problem. Keep an eye out for any other unusual behaviour - you should hear the fuel pump priming when you switch on, see the tacho reading while cranking etc.
Good luck and I hope this gets you closer to the problem. I'm sure you'll track it down eventually.
BTW if you're definitely got an ignition problem, you may want to disconnect the fuel pump while you investigate it. Make absolutely sure you remember to reconnect it afterwards though! And keep the battery charged up.
Cheers,
Peter Humphries (and a green V8S)
Gassing Station | Chimaera | Top of Page | What's New | My Stuff