crazy speedometer!!

[Project Draven]

well my speedometer for the longest time was going up and staying at 60 as soon as i would start moving but sometimes it would work off and on through the days. but about a week ago my speedometer started acting crazy it jumps all around and i was going out the road by my house at about 35 or so and my speedo was pinging 170 then jumping down and up all through the mph. and if i sit still and rev my car the speedometer will jump up but come back down i don't know what could be the problem could anyone please help me out
thanks in advance
brandon

 

[ddavisaf]

First, get those spark plugs you have in out of your car. Or, update your profile.
NGK BPR 6ES gapped at .028" or Autolite 63's
Nothing else, period.

As to the speedo. First things to check would be a bad Vehicle Speed Sensor (VSS) or a bad Reed Switch. The Reed Switch is located in the instrument cluster and it's what actually moves the needle.

 

[Project Draven]

ok will do on the spark plugs and for the sensor what is the proper testing for it i just found my multimeter tonight and i was thinking of testing it tomorrow

 

[ddavisaf]

The "easiest" way to narrow it down is this. Pull the VSS out of the car and hook up the drive gear to a drill. Turn it to the run position (or you might have to start it) and start the drill a turning. If the vehicle is still jumping around a bunch hook up the multimeter to the connector and monitor the pulses. If the pulses are erradic then the VSS is bad. If the pulses are not erradic the reed switch is bad.

 

[ddavisaf]

Keep in mind you're not actually driving the car, you're simply watching the speedo.

 

[Project Draven]

ok thanks all i will check thay out but i have been searching on here and i would like to know why these boshe platinums are bad for this car and could it be my hesitation problem before i boost?