Does anyone have any idea regarding the cause of the intermittant symptoms I described in my original post of 10-11-15 titled "strange symptoms?" Engine runs rough and occasionally stalls but restarts easily. At the same time if I put it in park and rev the engine the speedometer and odomoter both move even though I am in park. At other times both symptoms disappear and car runs fine. I replaced a cracked thermo vacuum valve but the problem persists. Engine temp not a factor.

94 camry LE 4 cyl

 

The speedo and odo receive a signal from the speed sensor located on top of the trans diff. The sensor has a gear that rotates with the diff ring gear. If the ring gear (aka axles) are not rotating there should be no signal generated.

The park/neutral/gear indication switch on the trans is connected to many items including the engine computer. If the speedo/odo are jumping around when the trans is in gear around there might be problem with the wiring, short, etc.

Find the speed sensor and disconnect the wiring harness plug. Determine if the speedo/odo still jump around under the conditions stated.

This issue could be related to the stall but ? Try cleaning the IAC valve.