Everywhen Posted September 17, 2023 Report Share Posted September 17, 2023 This evening while out for a spin, my 2.7 986 started to get a small misfire below 2000 rpm, once above that it runs as smooth as usual. Not lacking in power. Starting its OK but idle a little lumpy as if one cylinders is randomly not firing. I’l put the OBD scanner on it tomorrow but I get the feeling nothing will be recorded. I immediately thought coil packs and plugs as I’ve not changed these and I have no record of when they were last changed. I also thought maybe MAF or O2 sensor? Anyone got any suggestions where I should look? Quote Link to comment Share on other sites More sharing options...
BBB Posted September 17, 2023 Report Share Posted September 17, 2023 Disconnecting the MAF will default to a base map. If the symptoms remain then it’s not the MAF. Quote Link to comment Share on other sites More sharing options...
½cwt Posted September 17, 2023 Report Share Posted September 17, 2023 A misfire might show up on OBD even without a CEL on the dash. If it is one side could be O2 sensor, a single coil pack or variocam solenoid, if random then MAF would be a candidate. Quote Link to comment Share on other sites More sharing options...
Everywhen Posted September 18, 2023 Author Report Share Posted September 18, 2023 Fired up the OBD, Bank 2 oxygen sensor. I’m pretty sure they have never been changed. 1 Quote Link to comment Share on other sites More sharing options...
charlieboy2608 Posted September 21, 2023 Report Share Posted September 21, 2023 On 9/18/2023 at 10:52 AM, Everywhen said: Fired up the OBD, Bank 2 oxygen sensor. I’m pretty sure they have never been changed. Which sensor?-pre or post cat? What fault code was stored? Bank 2 is passenger side on a UK car. Quote Link to comment Share on other sites More sharing options...
Everywhen Posted September 21, 2023 Author Report Share Posted September 21, 2023 P0154 State:Current O2 sensor ahead of catalyst convertor . Bank 2 Quote Link to comment Share on other sites More sharing options...
Everywhen Posted September 29, 2023 Author Report Share Posted September 29, 2023 O2sensor was in so tight I was in danger of breaking it so took it to my local Indy who swapped them both. Even with it glowing like a cherry they put up a fight. O2 code no longer showed but misfire was still there on idle and PWIS now showed a misfire on No4, so I got them to change the coil packs and plugs, it was next on my list of jobs anyway. Misfire cured and engine really smooth now. Plugs were a lovely “biscuit brown” which was nice to see. Quote Link to comment Share on other sites More sharing options...
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