Help us help you. By posting the year, make, model and engine near the beginning of your help request, followed by the symptoms (no start, high idle, misfire etc.) Along with any prevalent Diagnostic Trouble Codes, aka DTCs, other forum members will be able to help you get to a solution more quickly and easily!
Having an issue for code p0340.You would think an easy diag.Have 5 volt ref. and no voltage drop on lo ref.Issue comes to light when disconnecting sensor and having issue with drop down voltage between 4.2 and 4.5 volts and struggles to reach good square wave on lab scope clipped on way up.voltage dropped all ground and power circuits to pcm ok. sent computer out for repair and was told proccesor was n/g.had them replace and ship back to us.before starting engine with reman pcm i checked drop down voltage and was at 4.98 volts.everything was fine till engine warmed up and code set for p0340 and rpm signal for cam sensor stopped working and dis connect voltage was 4.2 volts at drop down circuit.been thru 2 computers.only thing done mechanically is new cam and lifter dod deleted.
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