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95 RPM JUMPING ALL OVER WITH JUST POWER ON


bwd111
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With the ign turned just to power on only I tapped on the gas pedal and the RPM went from 0 to 4 . Then I take pos lead off battery and engine will start then die down the road and RPM does the same thing. Where would be a good place to start for looking at RPM problem I saw today with just power turned on? Is there a sensor that controls the pedal as well?

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So your RPM gauge is jumping without the engine running? If so...

Remove the gauge cluster and check the brass screws on the back of the flexible circuit board (they are the ground points). Check all connections for corrosion and fit, and there is also a voltage regulator that can fail IIRC, but you would have to search for that info, I don't recall it.

 

B

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Forgot to mention when RPM is going from 0-4 the check engine light comes on and the engine runs bad very bad until I pull the neg or postive lead off battery then everything is fine for about 4 miles then cycle starts again. What is the IIRC?

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I've been trying to figure out my tach too, typically when I start it, it will either peg out a 0 or 8000. Very rarely it will jump around, but never read correctly. Icve tried tightening the brass screws. Everything else on the cluster is correct, so I didn't think it was the voltage regulator. Could it be the crank position or tps? I guess its possible yo be the guage itself too.

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Sounds like the crank position sensor is sketchy. Warms up, gets erratic, that would explain the rough running and I'll bet it's what the tach gets signal from.

 

Also found neg cable was loose and battery slides around. I tighten cable down and engine didn't die for a day but going to look at CPS sensor today. Still odd that sometimes when just power is on before statrting just a slight tap on gas pedal would make rpm gauge go from 0-4 then a rest of the battery makes everything go back to normal and engine cranks over.

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Seems like the problem was the camshaft sensor located in the distributor. I went to junk yard and grabbed two camshaft sensors paid 15 bucks and chaged ou t the old sensor which was an after market and haven't had a problem since changing part. I ohmed out old part and ohms were very low compared to the two I pulled out of junk yard. I spent around 480.00 trying to find out the problem and all it was was a 15.00 dollar part. Now I have new fuel pump, ECM,fuel reg,ign switch with new key,new vac lines,new mass air flow sensor,ign coil,cap,rotor,new coil , ign module and TPS sensor.All which I replaced trying to find problem. Plus I bought used jeep liberty for 5k cause pathy was not running and I need something to drive. And all that was needed was $15.00 dollar camshaft sensor. Lesson learned

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Sounds like the crank position sensor is sketchy. Warms up, gets erratic, that would explain the rough running and I'll bet it's what the tach gets signal from.

 

You were 100% correct on the problem being the sensor camshaft sensor in the distributor. The wheel was also off and not making contact in the sensor.

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  • 4 weeks later...

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