rbodor3 Posted July 26, 2014 Report Share Posted July 26, 2014 150k miles Started with misfire only in 3rd gear 3000+ rpm, very intermittent. Then started getting misfire intermittent in RH turns. Then started getting misfire in straight lines in 5th 3000+rpm, under load. At this point started getting P0353 and P0332. Swapped plugs for Bosch coppers, 028 gap. Misfire continues. Swapped plugs for Champion coppers, 028 gap. Misfire continues. Replace all (5) COP for iPD version. Misfire continues. Check wire leads to Knock sensors - all look OKay. Misfire continues, only in hard RH turns (hard LH = no misfire.) Recently misfire is constant. P0353 constant. iPD cylinder 3 COP cracked. Swapped in (4) OEM ones, all had hairlines before, and cracked them. I have continuity between plug 3 transistor/signal wire >> ECM pin 50. Pin 4 = 14V when motoring, Pin 3 = gnd, Pin 1 = some PWM signal. What's interesting: cylinder 3 connector has 5V on Pin 1 almost consistently, whereas all the other cylinders show an obvious PWM signal frequency. What could be causing the signal to be seeing 5V all the time? I checked for a short to battery and don't have one. bad knock sensor? bad ECM? Link to comment Share on other sites More sharing options...
rbodor3 Posted July 26, 2014 Author Report Share Posted July 26, 2014 Opened up the wire loom down to the transmission, all of it is A-OKay. Have continuity back to the ECM, and open circuit to ground and battery on the pin 1 (signal wire.) Pulled the ECM and opened it up. Some light evidence of a very thin film of oil around the edges but the circuits were all dry and clean. Link to comment Share on other sites More sharing options...
rbodor3 Posted July 26, 2014 Author Report Share Posted July 26, 2014 serpentine belt rubbed through the wiring to the ECM. COP #3 transistor wire was nearly rubbed all the way through. Will post pictures shortly Link to comment Share on other sites More sharing options...
rbodor3 Posted July 28, 2014 Author Report Share Posted July 28, 2014 Link to comment Share on other sites More sharing options...
Ihatespeedbumps Posted July 28, 2014 Report Share Posted July 28, 2014 Nice work tracking down the problem! To prevent further problems you may want to find the metal bracket that harness slides into Link to comment Share on other sites More sharing options...
rbodor3 Posted August 1, 2014 Author Report Share Posted August 1, 2014 While tracing the wiring at the COPs I found many of the connectors were damaged and wiring right off the connector was worn (some even had small amounts of exposed wire, meaning the terminals couldn't be reused in a repair.) I therefore rebuilt the COP connector harness. Outside of regular items (heat shrink, iron, loom..) what follows is what you need to know. The Volvo PN is 9456341 for the connector: But you'll notice it doesn't include the terminals, and can be costly through the dealership; however, knowing this is a Bosch connector (orange seal is their marking) I looked through the catalog. I also purchased the terminals pre-pinned to wires (although the wire grade isn't as resistant as the OE, it should suffice for the next 100k miles,) and the plugs (since this is a 3-wire COP with a 4-cavity connector.) Connector - 1928403112 Plug - 1928300601 Terminal - 929939-3 Seal - 1928300599 Link to comment Share on other sites More sharing options...
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