Slight problemette
Discussion
Hmmm. Entertaining new fault appeared. I know what I think it is, but here's one for you amateurs 
Car had been running fine, driving around in good weather, stereo on, cooling fan running, heater fan on low.
Pulled into a BP station to get more fuel, car restarted no problem. Went to launch from garage exit and car stalled with a snatch of rear tyres.
Restarted OK, tried again, got 4 feet and died. Repeated 4 or 5 times. In the end I just turned the engine over on the starter to get back into garage via other entrance. Restarted, idled OK, blipped throttle and seemed OK. Drove across forecourt OK, slightly less aggressive exit proved OK. Car ran fine for 20 miles till I joined a dual carriageway, headed for outside lane, lights on and engine died. Indicator, then hazards as I head for hard shoulder. Stop car, oil and ignition lights on. Start engine OK, lights go out, car pulls away fine.
I think that maybe some electrical glitch is present so I drive 30 miles on sidelights, no fans, no stereo and no problem. Ran car to an indicated 1.3kWh/nM <ahem> to see if I could provoke a fuelling glitch: nothing.
Get to within 10 miles of home and as soon as I flip up headlights, car dies. Turn ignition off and back on, car resumes OK for a few hundred yards then dies again. Key off then on, engine cuts back in. Repeat a few more times, by which time I'm down slip road and into my area. No further problems.
Fan belt is OK, charge light works OK, voltmeter says 13v or so when running and doesn't change when driving. However... bizarrely, the tacho needle swings up and down in time to the indicators... but only above about 3000 rpm!
Initially I was tempted to blame the BP fill-up, but the way it dies is not indicative of fuel starvation/ water contamination.
Right, give it your best shot! Nearest to what I find wrong gets a signed picture of naked cloggies hot-air ballooning over the cooling towers at Ferrybridge power station
Car had been running fine, driving around in good weather, stereo on, cooling fan running, heater fan on low.
Pulled into a BP station to get more fuel, car restarted no problem. Went to launch from garage exit and car stalled with a snatch of rear tyres.
Restarted OK, tried again, got 4 feet and died. Repeated 4 or 5 times. In the end I just turned the engine over on the starter to get back into garage via other entrance. Restarted, idled OK, blipped throttle and seemed OK. Drove across forecourt OK, slightly less aggressive exit proved OK. Car ran fine for 20 miles till I joined a dual carriageway, headed for outside lane, lights on and engine died. Indicator, then hazards as I head for hard shoulder. Stop car, oil and ignition lights on. Start engine OK, lights go out, car pulls away fine.
I think that maybe some electrical glitch is present so I drive 30 miles on sidelights, no fans, no stereo and no problem. Ran car to an indicated 1.3kWh/nM <ahem> to see if I could provoke a fuelling glitch: nothing.
Get to within 10 miles of home and as soon as I flip up headlights, car dies. Turn ignition off and back on, car resumes OK for a few hundred yards then dies again. Key off then on, engine cuts back in. Repeat a few more times, by which time I'm down slip road and into my area. No further problems.
Fan belt is OK, charge light works OK, voltmeter says 13v or so when running and doesn't change when driving. However... bizarrely, the tacho needle swings up and down in time to the indicators... but only above about 3000 rpm!
Initially I was tempted to blame the BP fill-up, but the way it dies is not indicative of fuel starvation/ water contamination.
Right, give it your best shot! Nearest to what I find wrong gets a signed picture of naked cloggies hot-air ballooning over the cooling towers at Ferrybridge power station
Edited by Wedg1e on Monday 1st October 00:05
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jeff m said:
Intermittant ground to ignition
Hmmm... see where you're coming from, but it'd be a bit of a coincidence if (as it seems) every time I switched off and back on, it came straight back in...Just to narrow it down, although I knew it was unlikely to be the cause I have checked charge voltage and current, with and without headlamps (main and dipped), cooling fan and heater fan. Battery terminals are tight and clean as are the alternator terminals.
With everything on (and at idle) the alternator can maintain 12.5v to the system with about 2-3A of charge current reaching the battery. Off-load the alternator sits bang-on 13.8V. The starter motor hit 154A peak during cranking (warm engine).
The engine didn't cut out once in about 30 mins of testing.
There's about 8mA of current flowing between the engine block and the battery negative with the engine running...
Wedg1e said:
jeff m said:
Intermittant ground to ignition
Hmmm... see where you're coming from, but it'd be a bit of a coincidence if (as it seems) every time I switched off and back on, it came straight back in...Just to narrow it down, although I knew it was unlikely to be the cause I have checked charge voltage and current, with and without headlamps (main and dipped), cooling fan and heater fan. Battery terminals are tight and clean as are the alternator terminals.
With everything on (and at idle) the alternator can maintain 12.5v to the system with about 2-3A of charge current reaching the battery. Off-load the alternator sits bang-on 13.8V. The starter motor hit 154A peak during cranking (warm engine).
The engine didn't cut out once in about 30 mins of testing.
There's about 8mA of current flowing between the engine block and the battery negative with the engine running...
My logic or lack of, feedback thru turn sigs at over 3k revs.
Extra load on ignition is just enough to make the contact go intermitant.(and feed back thru anything convenient)
Ok, if you switch off ignition it restarts, that would be confirmation of an arcing contact somewhere. nes pa.
Anyway good luck
Suspect you may have already found it.
With intermittant lack of sparks plus tacho fluctuating then your fault can be ignition amplifier. They play up before dying and as the fault reacts to battery voltage or load changes (tacho varying in sympathy with indicators, ignition failing in sympathy with headlamps) so the purely "electronic" amplifier may just be that sensitive. However as with most electrical faults, rechecking all the local earths may be called for. Another component that is sensitive to voltage changes and may therefore react intermittantly is the ignition suppression capacitor, if fitted.
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