Diagnosis Help
Discussion
I have the most annoying misfire/non-running problem with my 1999 Superlight R that I'm hoping you good folks can help me track down.
The symptoms are an inability to run at all, or running (rough) for a little while with a heavy misfire (and associated backfiring) whenever the engine is revved or put under load. The misfire appears to be across all cylinders, and when it occurs the rev counter immediately drops to zero (then recovers). Perhaps as might be expected, it runs very rich under these circumstances.
I've tried all of the following to no avail (deep breath ...):
- changed coil, distributor cap & rotor arm.
- changed crank position sensor & throttle pot.
- changed battery master switch.
- swapped out ECU, immobiliser and black module under ECU for know good items.
- swapped out engine wiring loom for know good item.
- swapped out idle control valve for know good item.
- disconnected rev counter & gear change warning light.
- bypassed ignition switch.
- checked wiring to fuse box (& all fuses), loom connector behind fuse box & loom connectors in engine bay.
- checked all earths.
- checked fuel pressure.
So any ideas for other things to try, or better still diagnostics that I can run to determine exactly what the fault is? Is there test equipment I can use to try and identify where the problem lies, or recommendations for people who could diagnose what is wrong (I'm convinced it is electrical)?
Oh, and whilst we're at it is there a set of wiring diagrams available that actually relate
to what is in the car?
If it helps, it is a standard Superlight R on an EU2 Rover MEMS ECU.
The symptoms are an inability to run at all, or running (rough) for a little while with a heavy misfire (and associated backfiring) whenever the engine is revved or put under load. The misfire appears to be across all cylinders, and when it occurs the rev counter immediately drops to zero (then recovers). Perhaps as might be expected, it runs very rich under these circumstances.
I've tried all of the following to no avail (deep breath ...):
- changed coil, distributor cap & rotor arm.
- changed crank position sensor & throttle pot.
- changed battery master switch.
- swapped out ECU, immobiliser and black module under ECU for know good items.
- swapped out engine wiring loom for know good item.
- swapped out idle control valve for know good item.
- disconnected rev counter & gear change warning light.
- bypassed ignition switch.
- checked wiring to fuse box (& all fuses), loom connector behind fuse box & loom connectors in engine bay.
- checked all earths.
- checked fuel pressure.
So any ideas for other things to try, or better still diagnostics that I can run to determine exactly what the fault is? Is there test equipment I can use to try and identify where the problem lies, or recommendations for people who could diagnose what is wrong (I'm convinced it is electrical)?
Oh, and whilst we're at it is there a set of wiring diagrams available that actually relate
to what is in the car?
If it helps, it is a standard Superlight R on an EU2 Rover MEMS ECU.
F355GTS said:
Jeremy
I thought you'd traced the fault to the master switch/ alternator connections?
So did I. I thought you'd traced the fault to the master switch/ alternator connections?
Seems I was mistaken - my glee lasted for a hundred yards driving up the road until it misfired again. 
Still, at least it's become a permanent rather than intermittant fault now.
Thanks to everyone here and on Blatchat for your suggestions.
It looks as though I have fixed it: there was a failing crimp connection for the main ignition 'big brown wires' supply at the starter motor end.
Todays prize goes to F355GTS who I think suggested I checked this months & months ago. and double .
It looks as though I have fixed it: there was a failing crimp connection for the main ignition 'big brown wires' supply at the starter motor end.
Todays prize goes to F355GTS who I think suggested I checked this months & months ago.
and double . 
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