Page 1 of 3 123 LastLast
Results 1 to 10 of 26

Thread: P0300 and pulling my hair out!

  1. #1
    Member
    Join Date
    Mar 2009
    Posts
    94

    Default P0300 and pulling my hair out!

    I have been chasing my tail on this issue. The truck pops off when I kit the key then slows to a rough stumble of a idle after about 10 seconds or so it settles in and idles fine but with some missing. I have replaced or tested everything that I can think of still no dice. The truck started fine this morning when the temp was about 20F outside. I logged a start up, im out of ideas and starting to think this is a tune issue more then a part issue.

    The thing that bugs me is once you get above 10% it stops missing and pulls hard, I have a log of running down the road if anybody wants to see it. Any ideas would be great as I'm out of ideas!
    Attached Files Attached Files
    Last edited by haulinit; December 6th, 2010 at 04:11 PM. Reason: typo
    98 silverado 4wd excb 5.7l, zz4 cam,roller rockers, shorty headers, 0411 swap, Flash Scan V1 commercial

  2. #2
    R.I.P Shawn, 1956-2011 WeathermanShawn's Avatar
    Join Date
    Jul 2008
    Posts
    1,807

    Default

    Well, I certainly don't know your vehicle/OS as well as others..but a few questions...

    I see you have a current DTC for EGR. Did the problems start after you disabled EGR?

    Your LTFT's are pretty high (positive). That is equating to lean. Hard to know without an actual wideband, but thats a lot of +LTFT's for Idle.

    How is the health/age of your O2 sensors? Any chance of a log with H02S11 and H02S21 logged?

    Tune-wise, looks like you are running MAF-closed loop. You may just need to add some more MAF Airflow vs Frequency to correct those LTFT's.

    Thats all I can see on a quick look. Good luck.
    2002 Black Camaro Z-28 M6 Hardtop 11.0:1CR 425HP/410TQ SAE (400TQ@3500RPM)
    200cc Heads, 228/232 110+2 Cam, 1 3/4" LT's w/catts, GMMG, Koni Shocks, Hotchkis Springs, 35/21 Sways, 17" ZR1's, 3.90 Gears Roadrunner PCM LM-2 Serial Wideband
    EFILive Closed-Loop MAF/SD Hybrid Tune..


  3. #3
    Member
    Join Date
    Mar 2009
    Posts
    94

    Default

    I can log what ever you want me to log I'm very green in the tuning dept. The health or condition of my O2's is a ? I have not replaced them. No the DTC is from me not setting the mil's yet to reflect me blocking it off. I blocked the EGR off thinking it was stuck open and causing my missing condition. Thanks
    for the help
    98 silverado 4wd excb 5.7l, zz4 cam,roller rockers, shorty headers, 0411 swap, Flash Scan V1 commercial

  4. #4
    Lifetime Member
    Join Date
    May 2008
    Posts
    366

    Default

    It doesn't take much of a lean condition to cause misfiring. Did this issue start happening after tuning, the PCM swap, the cam swap?
    E85 is NOT flex fuel.

    2003 Chevy S10 4.3L LU3 LS1B Auto
    48 LB injectors
    Race Proven Motors 2114 intake
    T70 turbo.

  5. #5
    Joe (Moderator) joecar's Avatar
    Join Date
    Apr 2003
    Posts
    28,010

    Default

    Hi haulinit,

    Remove the pids O2BIAS11/12 and add the pids HO2S11/21, MAP and MAF, and capture a new log.

    How many miles on your O2 sensors...?
    Does coolant level stay the same...?
    Do you have any airleaks at/under the intake manifold...?
    What is condition of spark plug and wires...?

    +1 when did this start happening...?

  6. #6
    Member
    Join Date
    Mar 2009
    Posts
    94

    Default

    I have had the cam in for over two years with a Wheatley tuned black box, right before the PCM swap I was getting a high RPM miss above 4500 and WOT. If you didnt give it 100% throttle it wouldnt miss. Found out I had a bad injector replaced it and that took care of that miss. The truck started fine with the black box. After I switched to the 0411 it started having idle problems. The truck had 78,000 miles on it when I bought it, it now has 128,000 on it and I havent changed them. The coolant level stays the same ( I used the good fel-pro gaskets for the intake when I changed the cam). I checked for leaks and did not find any. New AC-Delco cap and rotor last night, plugs are about 1wk old. Tested the wires they were in good condition.

    The start up issue started after the PCM swap. I will have to change the PIDs tonight and go relog.
    Last edited by haulinit; December 7th, 2010 at 06:53 AM. Reason: Spelling
    98 silverado 4wd excb 5.7l, zz4 cam,roller rockers, shorty headers, 0411 swap, Flash Scan V1 commercial

  7. #7
    Member
    Join Date
    Mar 2009
    Posts
    94

    Default

    I was thinking if the truck was lean why would it start better when the temp was cold wouldnt that make it worse by making it leaner? Thinking out loud!
    98 silverado 4wd excb 5.7l, zz4 cam,roller rockers, shorty headers, 0411 swap, Flash Scan V1 commercial

  8. #8
    R.I.P Shawn, 1956-2011 WeathermanShawn's Avatar
    Join Date
    Jul 2008
    Posts
    1,807

    Default

    When your car first starts it is utilizing B3605 (Commanded Fuel). The colder it is the richer your fueling will be at start-up.

    The LTFT correction we were referencing is determined by B3802. The Idle LTFT's do not usually kick in until 60-70 C (PCM may reference Cold Idle Learning Fuel Cell).

    You are 'lean' when you enter closed-loop. You PCM believes you need more fuel and is adding an additional 11% fuel with every pulse of the injector. Again, colder more oxygen is available for engine..you may be starting out rich enough to start, but once you hit closed-loop you are immediately lean. Thats why you really need to know the status of those two front narrowbands. If they are slow, not switching properly, or have a significant intake leak..you could chase the problems for a long time.

    Hope that helps..
    2002 Black Camaro Z-28 M6 Hardtop 11.0:1CR 425HP/410TQ SAE (400TQ@3500RPM)
    200cc Heads, 228/232 110+2 Cam, 1 3/4" LT's w/catts, GMMG, Koni Shocks, Hotchkis Springs, 35/21 Sways, 17" ZR1's, 3.90 Gears Roadrunner PCM LM-2 Serial Wideband
    EFILive Closed-Loop MAF/SD Hybrid Tune..


  9. #9
    Member
    Join Date
    Mar 2009
    Posts
    94

    Default

    I think I may have miss lead you a lil bit. The fueling does not have time to go to closed loop fueling it starts to stumble the second the idle comes off the initial start then becomes rough. The idle slowly comes up to desired idle and smooths out.
    98 silverado 4wd excb 5.7l, zz4 cam,roller rockers, shorty headers, 0411 swap, Flash Scan V1 commercial

  10. #10
    R.I.P Shawn, 1956-2011 WeathermanShawn's Avatar
    Join Date
    Jul 2008
    Posts
    1,807

    Default

    No, I get it.

    Your initial Idle prior to entering closed-loop is the problem (cold-Idle). I was just stating that the health and age of your O2's will determine how quickly and efficiently you can enter closed-loop. The LTFT's are stored. There is some interplay on LTFT's and start-up. So if you are lean yesterday, the PCM will be trying to add fuel even on start-up (as you enter closed-loop).

    Its possible your VE Table may not be accurate. Do you have the ability to monitor or preferably log wideband AFR?

    So, we are 'guessing' on this end that it is fueling-related. I was just suggesting to verify that your O2's were up to the task. We only have the LTFT's at this point to make and educated guess. Either way, fresh O2's are never a bad idea.

    Good luck.
    2002 Black Camaro Z-28 M6 Hardtop 11.0:1CR 425HP/410TQ SAE (400TQ@3500RPM)
    200cc Heads, 228/232 110+2 Cam, 1 3/4" LT's w/catts, GMMG, Koni Shocks, Hotchkis Springs, 35/21 Sways, 17" ZR1's, 3.90 Gears Roadrunner PCM LM-2 Serial Wideband
    EFILive Closed-Loop MAF/SD Hybrid Tune..


Page 1 of 3 123 LastLast

Similar Threads

  1. Pulling tune
    By L31Sleeper in forum General (Diesel)
    Replies: 18
    Last Post: March 2nd, 2011, 08:05 PM
  2. Pulling timing for nitrous
    By SRT10KLLR in forum Gen IV V8 Specific
    Replies: 5
    Last Post: November 13th, 2009, 03:52 AM
  3. P0300 Code In Idle
    By sheamus in forum Gen III V8 Specific
    Replies: 12
    Last Post: October 7th, 2009, 12:31 PM
  4. Will pulling codes use a license?
    By Supercharged111 in forum General
    Replies: 6
    Last Post: August 7th, 2009, 03:32 PM
  5. Pulling timing
    By minytrker in forum General (Petrol, Gas, Ethanol)
    Replies: 10
    Last Post: August 27th, 2006, 05:40 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
  •