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V70 random misfire - continuing saga V70-XC70 2000

posted by  Robert S. on  Thu Sep 30 11:59 CST 2021
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last visit: Sun Sep 21 05:48 CST 2014
[RELATED]

2000 V70 SE AW-5 Denso 281k miles

Continuing this car's saga of nailing down root cause of #3 cylinder random misfire. You're probably familiar with my previous posts on this subject. To summarize:
- Misfire always occurs in #3. Sometimes it will be hundreds of miles/weeks until it recurs; sometimes the next day. No set pattern; very random and not dependent on engine load or speed. CEL just suddenly illuminates out of nowhere, then rough running.
- #3 Coil has been been both replaced and swapped numerous times.
- Coil receptacle housing has been replaced and repinned, with new wires spliced in upstream from the coil.

We're at the point in the troubleshooting sequence to pull the ECM, check/clean connections, and/or send ECM off for rebuild.

One glitch however: When ordering the ECM removal tool, the rep at ipd (usually a credible source) tells me that this tool won't work on Denso-equipped cars. Any one know with certainty if this is correct? And if so, is there an alternate tool used for removing the Denso ECM?

Thanks,
Robert







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    V70 random misfire - continuing saga V70-XC70 2000

    posted by  Marlin Mangels on  Fri Oct 1 04:17 CST 2021
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    last visit: Tue Oct 21 15:41 CST 2014
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    I had the same problem. Mine was also associated with coolant loss that could not be explained by external observation. No loss of compression when tested cold. My head was warped. Had it planed & new valves. Frustrating issue, I waited 3 years to finally dismantle engine. I love the car & am glad I had engine repaired.
    Marlin








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    V70 random misfire - continuing saga V70-XC70 2000

    posted by  riverbend on  Thu Sep 30 15:36 CST 2021
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    last visit: Wed Oct 22 15:29 CST 2014
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    Hi Robert,
    I'm not familiar with your previous posts. Ignore anything that you have already done.
    Change the spark plug. Switch injectors between cylinders 2 and 3. check the compression. Test your coolant for exhaust leaks.
    If you have done all those things fiddling with the ECM is the next step but I have not seen that be a problem. The Haynes manual has a drawing of an ECM removal tool (4A*8 8.29b). It is a 24mm X 1MM strip of steel with a slot cut in the end and a pop rivet. It works.
    Greg







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      V70 random misfire - continuing saga V70-XC70 2000

      posted by  Robert S. on  Sat Oct 2 09:48 CST 2021
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      last visit: Sun Sep 21 05:48 CST 2014
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      Thanks all for the suggestions and ideas.

      Spark plugs and exhaust / coolant leaks are pretty much ruled out; plugs are recently installed, coolant level is not dropping, no overheating, no sign of water vapor in exhaust, no steam cleaning inside cylinder and no overpressure in cooling system.

      Can try swapping injectors. Except, when a dead coil (no arc/spark) is coaxed into working again by re-plugging or swapping with engine running, I get arcs on the spark plug well wall and all is well again. This seems to be independent of injectors.

      Have never pulled the injectors. Anything in the procedure to be mindful of?

      Thanks,
      Robert








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        V70 random misfire - continuing saga V70-XC70 2000

        posted by  Chris Mullet on  Sun Oct 3 09:17 CST 2021
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        last visit: Fri Oct 24 09:08 CST 2014
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        Have you tried swapping spark plugs to see if the problem moves with it? Even new ones can occasionally act up. What kind of plugs are you using?








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          V70 random misfire - continuing saga V70-XC70 2000

          posted by  Robert S. on  Sun Oct 3 13:20 CST 2021
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          last visit: Sun Sep 21 05:48 CST 2014
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          Have swapped plugs around too; no effect one way or the other.

          Have used both Volvo OEM and NGK multi-ground electrode plugs during life of this car. Both brands perform well, although Volvo plugs have fallen out of favor lately because one of the plugs in a previous set blew out its center electrode.

          Currently using NGK four-ground electrode plugs (Nickel core - NGK 5767 / BKR6EQUA). No issues.







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