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RPM going insane

903 Views 9 Replies 7 Participants Last post by  CarJway
Today I was on the highway I had it in cruise control at 2100 RPM's, then the RPM started going up and then came back down to 2100 RPM's. The car did not rev and no other needles were going crazy. I thought it was maybe the cruise control so I turned it off but it kept happening. Even when I was at the traffic light it was doing it. I want to know what it could be and what can be done to fix it. Please help, when it comes to wiring, electronics, I have no idea on what to do or what can cause this.
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mine too........runnin down the road... tach jumpin to 4k..........stay there for a couple of seconds and then back to the right rpm......
My TPS was off. I did adjust it to .99, now I need to go on a long drive to see if it worked. It happened on my way back from a 1hr trip. Wish me luck :wavey
I'd suspect ground cables first.
i just added another engine ground...........could it be a bad ground in the dash ? my tach reads exactly 4 grand when it messes up....maybe a bad tach?
Well the ground cable thing makes some sense because lately my car won't start but all I have to do is move the battery cables a little and it turns on, or could it be that my battery is dying?
wait a minute. move your battery cables? meaning they are not tight to the battery? or the wire part of them? make sure they are tight to battery and if you just wiggle the cables themselves then i would replace your cables because of internal corrosion
2 things

1: fix your battery cables

2: if that doesnt fix (which it shouldnt) take out the gauge cluster, and check the 3 prongs that the tach plugs into. Clean them, and if they look okay, then trace some wires, good luck.
My 88 had a few tach issues. It would be fine some days and then jump every now and then.
Then the Ignition Module went out. Once I changed that, all my tach issue were fixed.

Oh and by the way, this left me stranded until 5 in the morning.:sterb:
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