Tach problems - Team Camaro Tech
Troubleshooting Diagnosing problems done here.

 
LinkBack Thread Tools Display Modes
post #1 of 4 (permalink) Old Dec 7th, 02, 10:24 AM Thread Starter
Senior Tech
 
Join Date: Mar 2002
Location: Santa Cruz,CA
Posts: 146
I have a ZZ4 engine with a HEI distributor. It seems like my engine runs fine, but at idle my tachometer bounces around 700 RPM's to around 2500 RPM's. The engine is still idling when the tach is jumping around. I checked my electrical connections, but they seem fine. I am not to familiar with an HEI distributor. If the cap on the HEI is cracked would this cause the tach to jump around, but wouldn't this also cause the car to idle rough? We have an Autometer street tach.
Thank you
Camaro_Kyle is offline  
Sponsored Links
Advertisement
 
post #2 of 4 (permalink) Old Dec 7th, 02, 04:43 PM
 
Join Date: Nov 2001
Posts: 138
Make sure you have your engine grounded to the frame and to battery. also make sure tach ground wire(black) is grounded.
jhow66 is offline  
post #3 of 4 (permalink) Old Dec 8th, 02, 08:20 PM
Senior Tech
Cameron
 
Join Date: Oct 2000
Location: Lexington, KY
Posts: 771
Look at the things mentioned above. If everything is good, measure the voltage that is feeding the tach while the engine is running and while the needle is bouncing. It would be preferrable to test the voltage with an analog multimeter. Make sure that the voltage that the tach is getting is constant 13-14v or so. The mulitmeter needle should not be bouncing while doing this test.

There is also the possiblity that the tach has malfunctioned. If you have a buddy with an extra one, hook it up on your car and see if it does the same thing.

------------------
69 Camaro
400 Small Block
Trick Flow Heads
Comp 282S solid cam
Performer RPM intake
750 CFM Holley
and a Muncie four speed
Pics of My Car
Cameron is offline  
 
post #4 of 4 (permalink) Old Dec 9th, 02, 03:22 AM
Super Moderator
Bess-68's rule
 
Everett#2390's Avatar
 
Join Date: Sep 2000
Location: Va Beach VA
Posts: 32,175
Garage
Good suggestions from jhow66 & Cameron.

My suggestion is the HEI unit has a TACH output on the connector. It is the unused terminal.

I guess if you had a stock wiring harness, it would be the unused terminal, but, with a custom set-up, I believe the terminal to use would be the outside upper left terminal looking at the dist cap with it removed and looking directly at terminals, place the four-pin connector at the 12 o'clock position.

Hopefully others here can verify this location.

------------------
Everett "OBJECTS IN THE MIRROR APPEAR QUICKLY UPON RAPID DECELERATION"
Everett#2390 is offline  
Sponsored Links
Advertisement
 
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Team Camaro Tech forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address.
NOTE we receive a lot of registrations with bad email addresses. IF you do not receive your confirmation email you will not be able to post. contact support and we will try and help.
Be sure you enter a valid email address and check your spam folder as well.



Email Address:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome