What causes my tacometer to bounce up and down and Jeep feels like it is loosing power when driving, 1995 V6

Tiny
MULDOON
  • MEMBER
  • 1995 JEEP GRAND CHEROKEE
  • 180 MILES
When I am driving my tacometer bounces up and down jeep feels like it is loosing power, then is okay after a few seconds, then starts again, I just changed the coil no differance.
Wednesday, November 23rd, 2011 AT 2:07 AM

20 Replies

Tiny
RIVERMIKERAT
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Check the grounds for the coil and the tachometer.
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Wednesday, November 23rd, 2011 AT 2:10 AM
Tiny
CJ MEDEVAC
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HAVE YOU RECENTLY EXPERIENCED A LOW BATTERY/ BAD CONNECTION AND HAD TO BE JUMP STARTED OR CHARGED?

https://www.2carpros.com/questions/2003-ford-escape-turn-car-on-speedometer-tachometer-peg-return-normal-starting

HAVE BATTERY AND CHARGING SYSTEM TESTED

MOST POPULAR AUTO PARTS STORES WILL DO IT FOR FREE

THE MEDIC
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Wednesday, November 23rd, 2011 AT 2:45 PM
Tiny
MULDOON
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I had been jumping a car weekly this Autumn, maybe that caused it, thank you Declan.
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Thursday, November 24th, 2011 AT 3:04 AM
Tiny
CJ MEDEVAC
  • MECHANIC
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DISCONNECTING BATTERY HELP?

THE MEDIC
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Thursday, November 24th, 2011 AT 3:52 AM
Tiny
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Jumping your car or another one? If another one, it can cause your alternator to go bad.
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Thursday, November 24th, 2011 AT 4:35 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
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I have actually seen not only the alternator go bad, but the voltage regulator, fuseable links fry. Have the system tested as described. In addition, make sure power from the alt is making it to the battery. With a bad fuseable link, the alt can check good but the power from it can not get to the battery.

They have given good advice.
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Thursday, November 24th, 2011 AT 4:54 AM
Tiny
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Have a Happy Thanksgiving, first, though.
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Thursday, November 24th, 2011 AT 4:58 AM
Tiny
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One more thing: Vehicle computers have been known to become damaged by jump starting when the cables aren't removed as soon as the jumped car starts.
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Thursday, November 24th, 2011 AT 5:08 AM
Tiny
MULDOON
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  • 79 POSTS
I replaced the computer 2 years ago, that was a big deal, I will try all suggestions, happy thanksgiving all, Deck
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Thursday, November 24th, 2011 AT 1:48 PM
Tiny
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Thank you, you too. Let us know what you find out.
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Friday, November 25th, 2011 AT 3:59 AM
Tiny
MULDOON
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I changed the battery but jeep still has the RPM needle jumps at certain times mostly around 45mph then surges slightly for a few seconds then okay.
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Sunday, December 4th, 2011 AT 3:15 PM
Tiny
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Have you checked the grounds? I've attached the schematic for the instrument cluster in 2 parts.
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Monday, December 5th, 2011 AT 2:44 AM
Tiny
MULDOON
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I took off and cleaned the IAC control sensor and so far so good after 2 days.
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Wednesday, December 7th, 2011 AT 1:50 PM
Tiny
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Good. Happy to hear it. Thanks for letting us know.
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Wednesday, December 7th, 2011 AT 5:41 PM
Tiny
MULDOON
  • MEMBER
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I replaced the battery, cleaned the IAC module and the jeep still does the same thing, the needle on the rpm bounces when I take my foot off the gas at around 40 mph, no engine lights on.
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Thursday, December 15th, 2011 AT 4:35 AM
Tiny
JACOBANDNICKOLAS
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You have to have a loose connection or the gauge itself is going bad. Check to make sure all connections to the PCM are tight, clean, and not damaged.
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Thursday, December 15th, 2011 AT 4:53 AM
Tiny
MULDOON
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Noticed today the rpm needle bounces before I move the car just after I start and idlying, any suggestions. Thanks Dec
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Friday, December 16th, 2011 AT 1:26 PM
Tiny
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Have you checked all of the connections as we have advised? As stated a few times, it's most likely either a loose connection or a faulty gauge.
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Friday, December 16th, 2011 AT 11:40 PM
Tiny
MULDOON
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Found the problem, the temp gauge was not working so I replaced the temp sensor on front of engine but did not know there is one on rear with a pin insert I hooked up that harness on sensor and everything is fine, no more tach bouncing or hesitating, the back Temp Sensor was loose
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Friday, February 10th, 2012 AT 1:35 PM
Tiny
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Cool. Happy to hear all is well now.

Closing thread.
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Friday, February 10th, 2012 AT 10:55 PM

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