Comavalanche Posted June 16, 2020 Share Posted June 16, 2020 My truck has recently started to run very rough; Low on power and very choppy. After about 30 minutes of driving it’ll clear up and run normal. Sometimes it’ll run perfect and then revert back running rough after it’s been driven a bit. According to my REM it’s using more than twice the fuel it should at idle (short term fuel trim when idling normal is ~50, when idling poorly it’s ~110.) My REM also says that all the sensors it gets information from are within normal operation. Does anyone have any ideas? Link to comment Share on other sites More sharing options...
Ωhm Posted June 16, 2020 Share Posted June 16, 2020 1 hour ago, Comavalanche said: According to my REM it’s using more than twice the fuel it should at idle (short term fuel trim when idling normal is ~50, when idling poorly it’s ~110.) STFT. Numbers less than 128 take fuel away by cutting back on INJ PW time. In other words the O2S is seeing RICH. Check O2S heater circuit. KEY OFF. Check continuity between D1_3 and D2_9. Looking for ≈6 ohms. Wiggle wires/lightly, very lightly tap O2S. Link to comment Share on other sites More sharing options...
Comavalanche Posted June 16, 2020 Author Share Posted June 16, 2020 7 hours ago, Ωhm said: STFT. Numbers less than 128 take fuel away by cutting back on INJ PW time. In other words the O2S is seeing RICH. Check O2S heater circuit. KEY OFF. Check continuity between D1_3 and D2_9. Looking for ≈6 ohms. Wiggle wires/lightly, very lightly tap O2S. I owe you a beer good sir! Thank you! Link to comment Share on other sites More sharing options...
fiatslug87 Posted June 16, 2020 Share Posted June 16, 2020 Was that it? What did your REM show for O2 voltage? It should cycle from low values to high values (~0.2-5.0) very quickly and one of the displays should toggle between Lean and Rich, also very quickly. Link to comment Share on other sites More sharing options...
Comavalanche Posted July 3, 2020 Author Share Posted July 3, 2020 On 6/16/2020 at 6:31 PM, fiatslug87 said: Was that it? What did your REM show for O2 voltage? It should cycle from low values to high values (~0.2-5.0) very quickly and one of the displays should toggle between Lean and Rich, also very quickly. So it appears as though I had a false positive....lol. I did everything he suggested, plus I swapped a known good relay with the 02 heater relay and it ran perfect - until it didn't. It ended up being a bad connection for the cylinder one fuel injector going into the ECU. Link to comment Share on other sites More sharing options...
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