4.0L High Idle

Discussion in '1989 - 1992 Ford Ranger' started by BuckarooBlue, May 7, 2023.

  1. BuckarooBlue

    BuckarooBlue New Member

    I have a 1992 Ford Ranger STX 4x4 with the 4.0L OHV and i have been having issues with a high idle. At the moment my truck idles about 1250rpm and its only given me running lean codes. I've replaced the fuel pump, fuel filter, injectors, IAC sensor, Air temp Sensor, throttle position, Oil pressure sensor, O2 sensor, better flow headers, new cats, and replaced the whole engine (due to my oil filter falling off while driving and murdered the engine). I've been chasing this problem for a long time now and haven't gotten anywhere. I've gotten tips to do a full clean and coat on my lower and upper intake manifold. I don't think it would change anything if i were to do a full clean and coat since my O2 sensor still inst switching and says its running lean. I've gone through and checked the wiring harness to the O2 sensor and its reading the full volts that it should. I'm really at a loss and in need of some experience with this kind of problem.

    Note I have gone through all gaskets related to exhaust and have no leaks.

    I also have a oily clutch issue, but I have no leaks on the top end of the engine that would be causing that issue, just super burnt out and I hope I'm not the only one who dealt with this issue.

    Constant Codes are 172 and 411

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