RPM Needle going crazy!

Tiny
TLOWDON
  • MEMBER
  • 1994 NISSAN PATHFINDER
  • 180,000 MILES
On my 94 Pathfinder SE V6 Automatic yesterday I noticed while driving the RPM Needle jumped up to Redline then back down then it did it again and again it did it a bunch of times then it would jump halfway then go back down and do it a bunch of times then it would go dead for a while and then start going crazy again then it would work normal for a while then start jumping and going crazy again. It's been doing this the past few days. The only thing I did before it was happening was gave a VW a jump and had an Oil Change. So if you could please Help and give me some suggestions I'd REALLY appreciate it! Thanks in Advance.
Saturday, February 18th, 2012 AT 1:25 PM

11 Replies

Tiny
RIVERMIKERAT
  • MECHANIC
  • 6,110 POSTS
You may have fried something in the ECU. Check the wiring to the distributor.
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Sunday, February 19th, 2012 AT 4:16 AM
Tiny
TLOWDON
  • MEMBER
  • 23 POSTS
Ok thank you very much!
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Sunday, February 19th, 2012 AT 5:17 AM
Tiny
TLOWDON
  • MEMBER
  • 23 POSTS
So if I did fry something what needs to be replaced? The ECU or the Distributor or Both and how will I be able to tell? I'm wondering if it has something to do when I jumped that car?
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Sunday, February 19th, 2012 AT 5:23 AM
Tiny
RIVERMIKERAT
  • MECHANIC
  • 6,110 POSTS
Most likely the ECU, unfortunately. Pay special attention to loose grounds and connections. There's also a control module under the right front seat. The grey wire there feeds the tach.
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Sunday, February 19th, 2012 AT 5:42 AM
Tiny
TLOWDON
  • MEMBER
  • 23 POSTS
Ok thanks again!
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Sunday, February 19th, 2012 AT 7:27 AM
Tiny
RIVERMIKERAT
  • MECHANIC
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My pleasure. Let us know what you find out and tell your friends about us!
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Sunday, February 19th, 2012 AT 9:47 AM
Tiny
TLOWDON
  • MEMBER
  • 23 POSTS
Ok sounds good I hope I can figure it out and I always tell my friends how Professional you guys are!
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Sunday, February 19th, 2012 AT 10:40 AM
Tiny
RIVERMIKERAT
  • MECHANIC
  • 6,110 POSTS
The tach signal comes from a couple of sources. There's a crank position sensor in the distributor, and the negative, or tach side of the coil. Those feed into the control module I mentioned above, which generates the signal to the tach.
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Sunday, February 19th, 2012 AT 9:08 PM
Tiny
TLOWDON
  • MEMBER
  • 23 POSTS
Ok I'm not to Mechanically inclined so I'll have to wait for a Buddy of mine to check it out thanks again!
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Monday, February 20th, 2012 AT 2:29 AM
Tiny
RIVERMIKERAT
  • MECHANIC
  • 6,110 POSTS
My pleasure. Let us know what you find out.
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Monday, February 20th, 2012 AT 3:12 AM
Tiny
TLOWDON
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Will do.
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Monday, February 20th, 2012 AT 4:40 AM

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