blackwolf
Member Since: 03 Nov 2009
Location: South West England
Posts: 16915
 
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Steve B wrote:Thanks blackwolf, much clearer. Thanks for taking the time to reply.
Ah, so its inside the insulation of each wire.
Steve
You're welcome. Yes, each conductor becomes a tiny hosepipe delivering trouble direct to your ECU! Smart design, isn't it!
Steve B wrote:
It only misfires at higher revs though, does it pass more current the higher the revs?
Steve
I imagine that in effect it probably does. I do not know for certain how the ECU actually drives the injectors, and I no longer have access to the test equipment needed to find out (I was a digital electronics engineer for a major telecommunications infractructure manufacturer for 20 years or so and it would have been easy for me to establish exactly how it works with the test equipment I had at my disposal then) but it is almost inevitable that since the pulses to fire the injectors will be more frequent at high revs the mean voltage and hence current in the injector firing circuits will be higher. Timing will also be more critical.
Having said that, please note from one of my earlier posts that when I had these symptoms in my TD5 Disco cleaning out the oil and renewing the injector harness made no difference at all, because it was actually a faulty throttle position sensor causing the problem. The TPS fault only logs an error code when the fault persists and the MIL illuminates, so whilst it is intermittent and in its early stages it isn't particularly easy to diagnose. As it worsens, it becomes repeatable (floor the throttle and it misfires) and eventually it will trigger a logged fault and MIL illumination.
Roger |
16th Nov 2010 12:32am |
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