Please Help with OBD II - Hot Rod Forum : Hotrodders Bulletin Board
Hotrodders.com -- Hot Rod Forum



Register FAQ Search Today's Posts Unanswered Posts Auto Escrow Insurance Auto Loans
Hot Rod Forum : Hotrodders Bulletin Board > Tech Help> Engine
User Name
Password
lost password?   |   register now

Reply
 
LinkBack Thread Tools
  #1 (permalink)  
Old 10-27-2003, 04:16 PM
bluesman123's Avatar
Member
 
Last photo:
Join Date: Nov 2002
Location: Bay Area, California
Age: 68
Posts: 593
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Please Help with OBD II

Hi Folks...I'm having problems getting my engine faults sorted out and would appreciate any help you can provide (my local GM dealer will no longer allow techs to "hand out free advice").

Basic Setup: I have a stone stock 98 GM 5.7 Vortec in a 91 Sonoma. For reasons not (I don't think!) related to this problem I am running it with a 1997 computer.

Problem: It just doesn't seem to run right. Hard starting...what sounds like a misfire but see below...plugs and exhaust pipes look a little carboned...doesn't want to idle...not as much power as I seem to think it should have.

OBD II Data: No trouble codes being set. No misfires being detected. Idles at 675-695.

O2 Sensors: Here's where I think the problem may be, but still with no error codes. This is the data...

>>While the sensors are warming up...
O1 = starts at 0.85V and slowly increases to 0.90V
O2 = Starts at 0.74V and stays there
O3 = Starts at 0.84V and slowly increases to 0.88V
O4 (which my scanner is calling 1B !!) = Starts at 0.45V and stays there

>> Once the sensors heat up I get this ....
O1 = Drops abruptly to about 0.70 V and cycles up and down from about 0.65V to about 0.75V
O2 = Drops abruptly to about 0.25V and cycles there about like O1 does ( plus/minus about 0.5V)
O3 = Still stays very stable at about 0.88V-0.90V
O4 = Jumps from 0.45V up to same as O3 and is very stable.

I wish I could post the graph as I'm not too good at describing what I see.

I swear this thing is running rough but no misfire is getting detected. I also think it is rich, but no error codes are being set.

I'm thoroughly puzzled (and more than a little p****d at the dealer who won't let me just show the graph to their tech guy.

Thanks for any help you can give me!!

Bluesman

    Advertisement
Reply With Quote Quick reply to this message

Recent Engine posts with photos

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the Hot Rod Forum : Hotrodders Bulletin Board forums, you must first register.
Please enter your desired user name (usually not your first and last name), your email address and other required details in the form below.
User Name:
If you do not want to register, fill this field only and the name will be used as user name for your post.
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 for yourself.
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.




Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools

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



All times are GMT -6. The time now is 12:15 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0 PL2
Copyright Hotrodders.com 1999 - 2012. All Rights Reserved.