What to look for during scan? - GM Forum - Buick, Cadillac, Chev, Olds, GMC & Pontiac chat

General GM Chat When starting new posts, please specify YEAR, MAKE, MODEL, ENGINE type, and whatever modifications you have made. Chat about all things GM (and related cars). Off-topic stuff should be in the Lounge, and all Model specific mechanical problems should be posted in the proper forum.

Thread Tools Search this Thread
Old 04-07-2006, 11:31 AM   #1
Senior Member
Posts like a Northstar
Thread Starter
Join Date: Jan 2005
Location: Richfield, MN
Posts: 781
Thanks: 0
Thanked 0 Times in 0 Posts
alec_b is on a distinguished road
Default What to look for during scan?

I'll be borrowing a scantool this weekend to moniter the performance of the O2 sensors in my dads '96 olds ciera 3100. What specifically should i look for? What can i watch to see if the O2'* are reacting slowly, or is something else isn't quite right. It'* got 2 O2 sensors also, pre and post cat. Thanks guys!
alec_b is offline   Reply With Quote
Old 04-07-2006, 11:42 AM   #2
Junior Member
Join Date: Mar 2004
Location: Purgatory
Posts: 0
Thanks: 0
Thanked 0 Times in 0 Posts
harofreak00 is on a distinguished road

numbers should jump all over the place, in both banks

mine goes from like 70-700 in a second
harofreak00 is offline   Reply With Quote
Old 04-07-2006, 12:34 PM   #3
Senior Member
True Car Nut
Join Date: Oct 2005
Location: Central Florida
Posts: 7,030
Thanks: 0
Thanked 0 Times in 0 Posts
lash is on a distinguished road

Also, #2 sensor (after cat) should be cycling slower than #1 sensor (in exhaust manifold).

Heres some info I posted yesterday from the FSM (it was for determining if a cat is bad, but the info on O2s is pertinent):

Check connections at the PCM and your wiring harness for backed out terminals, broken terminal locks, damaged terminals, and bad or worn wires. This especially includes the wiring on both 02 sensors.

If everything looks OK, then hook up your scan tool and watch the screen while moving connectors and wires that are related to the O2 sensors. A change in display will indicate a problem area.

Then monitor O2 sensor activity while in Park. If the activity level of both sensors is about equal, then there is a problem. Your 2nd O2 should show much less activity.

Then, if problem is still indicated, visually inspect the cat for dents, discoloration caused by severe temps, holes, or internal rattling. Also inspect exhaust downpipe and surrounding pieces for damage.
lash is offline   Reply With Quote

Related Topics
Thread Thread Starter Forum Replies Last Post
Need suggestions for coughing and sputtering during WOT 1994SSEi 1992-1999 5 06-22-2004 07:12 PM
what should i look at when i get my scan tool jachin 1992-1999 0 01-30-2004 11:21 AM
Before, during and after photos..WOW! Tamara Lounge 8 09-22-2003 01:35 AM
SES light during acceleration J Wikoff 1992-1999 2 08-20-2003 09:55 PM
Parking Brake Engages During Rapid Acceleration Quibbler82 1992-1999 4 06-16-2003 06:28 PM

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not 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 Off
Pingbacks are Off
Refbacks are Off

All times are GMT -4. The time now is 10:56 AM.

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.