Results 1 to 4 of 4

Thread: Log file help.

  1. #1
    Senior Member
    Join Date
    Nov 2007
    Posts
    149

    Default Log file help.

    What guys think. Do think my long fuel trims look o.k. I'm also getting the p0420 code and whanted know if there is anyway to tell if the cat bad by logging the pre and post 02 sensor like show in my log file.
    Thanks.

    LS1B_0007.efi
    2006 Trailblazer SS
    Twin Turbo 67 Chevy Truck
    SOLD Truck 2002 Chevy kb turbo t70 5.7l

  2. #2
    Joe (Moderator) joecar's Avatar
    Join Date
    Apr 2003
    Posts
    28,403

    Default

    Delete MAFFREQ and TRQTRANS and add MAF and EQIVRATIO and take another log (keep channel count at 24 or less)...

    After a freeway burst (over 55 mph, lots of throttle), when you come back down to idle, the PCM may test the cats, you will see the commanded EQIVRATIO transition rich then lean (or vice-versa) for a few seconds and then back to stoich, you will see the front O2 sensor respond to the EQIVRATIO transitions, the PCM times the response of the rear O2 wrt the front O2, if the response time is too short it fails the test (DTC P0420 or P0430).

    In your log I can't see any places where the PCM might be running the test, so take another log (at least 65+ mph, lots of throttle).
    Last edited by joecar; September 21st, 2010 at 01:51 AM.

  3. #3
    Senior Member
    Join Date
    Nov 2007
    Posts
    149

    Default

    Joecar,
    I did the log file way you asked looks like the rear 02 responding to slow. Can please take a look.
    Thanks
    Attached Files Attached Files
    2006 Trailblazer SS
    Twin Turbo 67 Chevy Truck
    SOLD Truck 2002 Chevy kb turbo t70 5.7l

  4. #4
    Joe (Moderator) joecar's Avatar
    Join Date
    Apr 2003
    Posts
    28,403

    Default

    That log file shows the cat monitor test running two times (see the EQIVRATIO cycling when VSS is zero).

    In each of those tests, the bank1 rear O2 responds in too short a time, so the test fails the bank1 cat; in attached pics, see rear O2 response time 5->6 for bank 1;

    the bank2 cat looks like it's about to fail also.

    With the scantool, you can look at the Mode $6 data to see how much the cat test failed by... connect scantool to vehicle, goto ODB-II tab, goto SMS subtab, look at the last 2 entries (OC/60 and OC/70) they show the measured response and the maximum allowed "shortness" of response time (i.e. minimum response time).
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

Name:	Cat tests triggered.png 
Views:	187 
Size:	137.7 KB 
ID:	9048   Click image for larger version. 

Name:	Test 2 Bank1 rear O2 responds in 1.7 seconds.png 
Views:	192 
Size:	120.5 KB 
ID:	9047   Click image for larger version. 

Name:	Test 1 Bank1 rear O2 responds in 2.4 seconds.png 
Views:	191 
Size:	121.2 KB 
ID:	9049   Click image for larger version. 

Name:	Rear O2 responses to CAT monitor test.png 
Views:	183 
Size:	116.4 KB 
ID:	9046  

Similar Threads

  1. No DTC's in log file
    By spandit in forum Black Box Logging
    Replies: 2
    Last Post: September 16th, 2010, 02:51 AM
  2. Lost log file
    By FeetDry in forum FlashScan V2 BB Logging
    Replies: 5
    Last Post: July 13th, 2010, 11:08 AM
  3. Cannot start new Log file
    By Gordy M in forum Gen III V8 Specific
    Replies: 7
    Last Post: August 30th, 2007, 11:46 PM
  4. Opening a log file?
    By jfpilla in forum General
    Replies: 5
    Last Post: June 27th, 2007, 01:24 PM
  5. Would someone be willing to look at a log file?
    By stigmundfreud in forum Gen III V8 Specific
    Replies: 5
    Last Post: May 6th, 2007, 08:47 AM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •