Pennock's Fiero Forum
  Technical Discussion & Questions
  Tachometer acting strangely

Post New Topic  Post A Reply
Email This Page to Someone! | Printable Version


next newest topic | next oldest topic
Tachometer acting strangely by blacknblue
Started on: 06-06-2014 03:35 AM
Replies: 5 (199 views)
Last post by: Mike142 on 06-06-2014 09:41 PM
blacknblue
Member
Posts: 167
From: Fairhope, AL
Registered: Jun 2011


Feedback score: N/A
Leave feedback

Rate this member

Report this Post06-06-2014 03:35 AM Click Here to See the Profile for blacknblueSend a Private Message to blacknblueEdit/Delete MessageReply w/QuoteDirect Link to This Post
87 2.5 with the Isuzu 5-speed. I bought the car about three years ago and it has been my daily driver ever since. The tachometer has never worked since i bought it. Being an 87, it is a DIS ignition, so i have no idea what is supposed to feed the tach its information. I've already changed the ignition control module, both coil packs, and the crankshaft position sensor. The "shift light" does work.

Yesterday, the tach decided to come back to life. It will ever so slowly creep to 6k RPM regardless of what the engine is doing. Sometimes it will continue to creep until it has made a full revolution, other times it will ever so slowly creep back down to zero. Is there any troubleshooting i can do to see if the tach can be made to work properly? Or is time to start shopping for a new gauge?
IP: Logged
PFF
System Bot
David Hambleton
Member
Posts: 1441
From: Stoney Creek Ontario Canada
Registered: Nov 2012


Feedback score: N/A
Leave feedback

Rate this member

Report this Post06-06-2014 12:32 PM Click Here to See the Profile for David HambletonClick Here to Email David HambletonSend a Private Message to David HambletonEdit/Delete MessageReply w/QuoteDirect Link to This Post
My '84 tach started reading 500 to 1000 rpm high. I got a tach assembly from a Pick & Pull for $10 & the problem was solved. (May not be your issue...)
My '86 tach dropped to 0 rpm a few times while driving. It would come back on by itself or if I whacked the console. (Connection issue...)
IP: Logged
TopNotch
Member
Posts: 3537
From: Lawrenceville, GA USA
Registered: Feb 2009


Feedback score:    (7)
Leave feedback





Total ratings: 59
Rate this member

Report this Post06-06-2014 02:32 PM Click Here to See the Profile for TopNotchClick Here to visit TopNotch's HomePageSend a Private Message to TopNotchEdit/Delete MessageReply w/QuoteDirect Link to This Post
This page may help.
And don't pay any attention if someone tells you to check the tach filter. The 87 and 88 2.5 cars don't have them.
IP: Logged
Ponnari
Member
Posts: 542
From: Seattle,WA, USA
Registered: Dec 2011


Feedback score:    (7)
Leave feedback

Rate this member

Report this Post06-06-2014 07:03 PM Click Here to See the Profile for PonnariSend a Private Message to PonnariEdit/Delete MessageReply w/QuoteDirect Link to This Post
Below is link on how to repair, Its pretty easy.
http://www.fieros.de/en/articles/tach.html
IP: Logged
blacknblue
Member
Posts: 167
From: Fairhope, AL
Registered: Jun 2011


Feedback score: N/A
Leave feedback

Rate this member

Report this Post06-06-2014 07:08 PM Click Here to See the Profile for blacknblueSend a Private Message to blacknblueEdit/Delete MessageReply w/QuoteDirect Link to This Post
That seems borderline indecipherable to me...
IP: Logged
Mike142
Member
Posts: 67
From: Bridgewater, NJ
Registered: Jun 2011


Feedback score: N/A
Leave feedback

Rate this member

Report this Post06-06-2014 09:41 PM Click Here to See the Profile for Mike142Send a Private Message to Mike142Edit/Delete MessageReply w/QuoteDirect Link to This Post
My tach was going crazy, turned out to just be a loose connection to the HEI module in the distributor. I have an 87 GT.

I'd venture a guess that one of your electrical connectors (somewhere) is loose, and/or was totally not connected. Either that or it's corroded and you have to clean/di-electric grease the connector to get it to make up nicely and give a consistent signal. The corrosion story works for a connector that isn't working at all, then decides to work because something allowed it to (water or some other reason the electrical signal could make it through the corrosion)

Hope that helps...
IP: Logged

next newest topic | next oldest topic

All times are ET (US)

Post New Topic  Post A Reply
Hop to:

Contact Us | Back To Main Page

Advertizing on PFF | Fiero Parts Vendors
PFF Merchandise | Fiero Gallery | Ogre's Cave
Real-Time Chat | Fiero Related Auctions on eBay



Copyright (c) 1999, C. Pennock