Tachometer reading fluctuates - JeepForum.com
Search  
Sign Up   Today's Posts
User: Pass: Remember?
Advertise Here
Jeep Home Jeep Forum Jeep Classifieds Jeep Registry JeepSpace Jeep Reviews Jeep Gallery Jeep Clubs Jeep Groups Jeep Videos Jeep Events Jeep Articles
Go Back JeepForum.com > Models > Jeep Wrangler Forums > YJ Wrangler Technical Forum > Tachometer reading fluctuates

Labor Day Sale!FS: 2007-2013 Jeep Wrangler "HALO" Angel Eye KitFS: Wranger BRIGHT License Plate LED! Just $3! Great value

Reply
Unread 04-29-2009, 11:24 AM   #1
Sambox
Registered User
1996 XJ Cherokee 
 
Join Date: Feb 2007
Location: Tucson, Arizona
Posts: 508
Tachometer reading fluctuates

I was driving down the interstate yesterday (65-75 mph) when I noticed that the tach would jump. I was cruising in 4th at about 2100 RPMs and it would jump up to 2400, then back down, the drop to 2000, then up again. I didn't notice any surging from the engine though.

Is there a sensor for the tach that could be going bad or is the flucuating a mechanical issue? Or do I not need to worry about it?

__________________
"Jeeps are the equivalent of barbies for men."-JaikYJ

1996 Cherokee XJ, All stock except for a Flow Master exhaust.........for now. He He.

http://www.cityprofile.com/forum/tucson/
Sambox is offline   Reply With Quote
Unread 04-29-2009, 03:01 PM   #2
dodger889
Registered User
1989 YJ Wrangler 
 
Join Date: Jan 2009
Location: mi
Posts: 4,162
If you are still orginal the signal comes from the ecm drives the tach.
__________________
A 89 yj with a 4.0 aw4 sye out of an 92xj. Now the hard part is done time to get it up in the air just a bit. Working on 8.8 with 3.73 and lsd for the rear. and new D30 hp with 3.73 .
For those who have not figured this out I'm old school but can handle the new too.
Quote:
Originally Posted by bigsquat View Post
im just cheap, and cheap makes you creative.
dodger889 is offline   Reply With Quote
Unread 04-29-2009, 03:58 PM   #3
Smash209
Registered User
1991 YJ Wrangler 
 
Join Date: Aug 2001
Location: CT
Posts: 333
Did you recently replace the speakers with better, ie bigger magnet ones? Its the speaker next to the tach causing it to jump a little when the bass hits (ha... bass out of a 4x6)
__________________
~~~ \\ // ~~~ ,,,,,, ~~~~~~~~~~
~~~~ //~~~~~|| ~~~~~~~~~~~~
~~~~//~~~~~ ||~~~~~~~~~~~~
~~~~~~~~~ \\// ~~~~~~~~~~~~
Smash209 is offline   Reply With Quote
Unread 04-29-2009, 04:36 PM   #4
Sambox
Registered User
1996 XJ Cherokee 
 
Join Date: Feb 2007
Location: Tucson, Arizona
Posts: 508
Yeah, I'm all original and no, the speakers have not been changed...at least by me. This is the first time I've seen/noticed it happen.

So for it to fluctuate, the ECM is sending false signals? Is this indicating a bad ECM?
__________________
"Jeeps are the equivalent of barbies for men."-JaikYJ

1996 Cherokee XJ, All stock except for a Flow Master exhaust.........for now. He He.

http://www.cityprofile.com/forum/tucson/
Sambox is offline   Reply With Quote
Reply
Thread Tools


Suggested Threads





Jeep, Wrangler, Cherokee, Grand Cherokee, and other models are copyrighted and trademarked to Jeep/Chrysler Corporation. JeepForum.com is not in any way associated with Jeep or the Chrysler Corp.