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Possible Causes of intermittent Loss of spark

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  • Digitalwave
    replied
    You're right, the 2.5 GN from the C101 is not shielded. The other one (pin 1 from the DME and the diagnostic connector, which is I guess the signal wire) is shielded.

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  • digger
    replied
    I don't think coil positive would be shielded?

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  • Digitalwave
    replied
    One of those wires (I don't remember which) is shielded. Some of the shielding might have been in the splice causing an intermittent ground.

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  • digger
    replied
    So the positive battery supply at coil was dropping out intermittently but the supply green 2.5 wire near battery tray direct from pin 7 of c101 did not. The PO had installed an alarm and the coil supply was cut and routed to an alarm. I bypassed that and seems to be running like a champ.

    Oddly enough alarm has never been used in the last 15 years and has never given a problem in it's supposed disconnected state. So I don't know if it was bad connection in the alarm harness or something to do with actual alarm. Nevertheless it's been bypassed now.

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  • digger
    replied
    can confirm the coil +12V ignition switched supply is intermittently dropping out. rigged up a test light. presumably a bad wire/ connection

    whats the best way to isolate ? just trace back? given everything else on ignition switch feed still works its probably relatively localised to the coil and not a wider issue with the circuit

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  • digger
    replied
    did some further checks. with test light on +12V of the coil connector the incandescent test light went out as engine cutout but came back on a second o two after it stopped running( it seemed to coincide with the fuel pump witching off). perhaps a coincidence? i'm starting to suspect a possible intermittently bad +12V switched ignition circuit (in particular a dodgey wire to the coil). i wonder if the fuel pump is somehow related.

    if only it would fail consistently so i could do a test and repeat it several times to confirm behaviour. this contradicts what i saw with the cranking a day or so ago but that was with a LED test light.
    Last edited by digger; 09-01-2019, 05:14 PM.

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  • digger
    replied
    had multiple cut out occurences that were able to be restarted immediatelty. Fortunately one cut out occurence would not restart for 5min just cranked continuously no spark on any cylinders.

    so test light suggests the coil is faulty as with and without the issue the test light behavious was the same.

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  • digger
    replied
    so as the car was at my mechanic getting road worthiness done he had not had a chance to do anything until today as he was away.

    he had charged the battery as it was only 12.2V when he chekced which is odd after having driven it for 1 hr or so should have good charge.

    So today it started fine and could not replicate the issue. he said that the alternator might not be charging the battery sometimes. when i got home the voltage with engine running (idling) was 13.5V with aux fan and lights on, but when i put cabin fan on hi and turn a few other things on the voltage dropped to 12.5V. so it seems the alternator is probably sketchy. last time i checked it was 13.8V or so a while back

    it may have nothing to do with the issue but sounds like a replacment is needed. its probably the original so he said might as well replace whole thing rather than voltage regulator only.

    what say eveyone? and where do you get a good reco unit qulaity brand OE or bosch etc

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  • digger
    replied
    No I don't see it as being the issue as I get a crank rpm signal when there's no spark and when I log it cutting out it correctly shows rpm dropping down in time ( it doesn't drop out instantaneously )

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  • Kershaw
    replied
    You swapped the crank sensor. Have you tried swapping the harmonic balancer?

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  • digger
    replied
    Originally posted by varg View Post
    Does the Wolf ECU software have an test mode you can use?
    not that i'm aware of.

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  • varg
    replied
    Does the Wolf ECU software have an test mode you can use? That would be the best bet, triggering each output manually and keeping it on longer than it would be with a cranking test so that you can see signal on a test light or meter easily. At cranking dwell I think you should be able to see a LED flash, but it has been a long time since I tested an ignitor in a car so I don't remember how well that works.

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  • digger
    replied
    yes that's it i also found a motec doc attached that shows wiring properly. i didnt test signals previously because i didnt have that datasheet with pins identified and i thought i needed a scope which i dont have. im going to test it and if its the ignitor (my thoughts are heat damage) as a possblity and if so i will get a new one and relocate to cold side of engine. might be good idea regardless of it being the issue

    coil 9220061800
    https://www.nzefi.com/product/bosch-...inder-engines/
    Attached Files
    Last edited by digger; 08-16-2019, 05:07 PM.

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  • varg
    replied
    Which Bosch ignition module? This one? Test signal in and out of the ignition module, the symptoms match an ignition module that is overheating or on its way out. Seeing if it has signal in and out during the no-start condition would confirm eliminate it with certainty. If it is near the exhaust, being mounted on an AL block may not be enough, I believe the internal transistors have thermal protection and will cut out if temps get too high which is a good possibility given the heat of the exhaust area. The sheet metal and thus the heat sink the module is bolted to is also typically hot around the exhaust side and may be working against you. Typical OE installation of these coil drivers, as seen in turbo Volvos and other vehicles that use them, is on the side of the engine bay opposite of the exhaust. I don't know what Wolf ECU circuitry looks like but it's unlikely to be failing or overheating ignition transistors in the ECU, the ignition module input current is rated at 10-20mA which is well within the spec of any ignition output on any ECU I've heard of.
    Last edited by varg; 08-16-2019, 01:13 PM.

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  • digger
    replied
    the ECU tech support just replied and said a LED test light will work to see signal to Igniter and reverse polarity with test light to test whats coming out igniter. obviously check common 12V at coil and ground at igniter first working back towards ECU

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