Occasionally stops firing on low throttle

Discussion in 'Technical' started by PWilson, Mar 9, 2019.

  1. PWilson

    PWilson New Member

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    Hi guys. After a bit of advice, please, as this doesn't seem common and has me stumped.

    The car's pretty old and not the flashest thing, I'll admit. But it runs pretty well for the most part. But over the last little while, a problem's developed where if I'm cruising at low/maintenance throttle at ~2.5k RPM, occasionally I'll lose drive. It feels like it stops firing. Everything else is working, but I the engine just seems to be doing nothing. If I give it more throttle at this point, most of the time it will kick back on (and backfire). But if I back off, it'll stop firing again. Occasionally it will not fire even with a bit more throttle. At this point, I clutch in and throttle back on gently, and holding a medium throttle will get it firing again. So I put it in a lower gear and let it rev a bit harder for a while, and can then go back to the cruising gear and it's all good.

    Any thoughts?
     
  2. beaver

    beaver southern zeds

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    Check the ptu.. by swapping it over for one that is known to be good.
     
  3. East Coast Z

    East Coast Z Well-Known Member

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    The fact it backfires when it kicks again would indicate the problem is ignition related.
    The easiest & coincidently the first thing to check would be ignition system wiring connections.
     
  4. IB

    IB ?????

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    Does it have blow off valves? If so they may need cleaning and re-lubing
     
  5. Chrispy

    Chrispy Pretentious Upstart

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    Also ignition timing...
     
  6. PWilson

    PWilson New Member

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    Thanks for the advice. I hadn't heard of the PTU before so I'll look into that.

    I wouldn't have thought it would be a wiring problem if it's consistently happening on lower throttle and solved by opening the throttle (feels not random enough to be wiring). But definitely main suspicion was ignition related. Just not really sure what to check.

    No blowoffs. Fairly stock, if tired, TT manual.
     

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