jQuery not supported.



o2, mass air, misfire codes after new exhaust...help!!

o2, mass air, misfire codes after new exhaust...help!!

Postby CJ_03_2500HD [OP] » Jan 07 2014, 6:00am

I have a 2003 2500HD 6.0 automatic non allison trans. I got exhaust put on at my local exhaust shop last saturday, the jackass who put a new cat on the truck a few years back shoved exhaust pipe inside the cat hitting the o2 sensor and damaging it instead of clamping it or welding it the right way. I got two new cats, pipe, and muffler from the cats back. The OBD2 showed codes for the o2 sensor downstream (which was the bad one) and cat codes. I cleared them on my tuner when I got home which was 5 minutes from the shop. I realized the truck was running a little rough since the hole for the o2 sensor was plugged until I could get one for half the price they wanted and I could put in myself. I had to order the sensor so it took a few days but it only took a day for the truck to run bad enough I didn't drive it for a week. I put the new sensor in, new plugs, and changed the oil yesterday, it still ran terrible. Today I bought new wires since the codes were still there, i also changed out coils 6 & 8 because my friends scanner said they were the two misfiring even after the new plugs and wires. Needless to say its still running bad and i put the tune I originally had back on and it runs better and it showed there were no misfires as it was running but o2 sensor codes for all 4 were showing and mass air code. I cleared the codes and drove it about 3 miles and plugged it back in after and all the codes were back AND about 4 cylinders were taking turns misfiring... Im so fed up with this damn thing and I work on cars for a living and so do my friends that helped me and were all stumped. Our next thought is to take the intake off and valve covers to make sure theres no internal damage from the backfiring. We also re-learned the crank position and it was successful but still no help. Someone PLEASE help with this, Im so frustrated and tired of spending money to rule things out even after testing them showed it should be done. I can't get on this forum too often so please email me with the subject "chevy forum help" my email in cjackman911@gmail.com. Thank you!
Original Poster
CJ_03_2500HD
Firing on 1 cylinder [L1]
Firing on 1 cylinder [L1]
Posts: 10
Topics: 1
Images: 3
Blogs: 0
Joined: Jan 07 2014, 5:30am
Location: Trenton, NJ
Year: 2003
Make/Model: Chevrolet Silverado
Extra Info: 2500HD 6.0L V8 4x4
Group Membership:
Registered users
Related Topics  Air intake mods - Ram air   Codes   Ok the codes are in..   Misfire causes?   misfire   help with RPO codes   O2 sensor codes   what are these trouble codes?   Error Codes....   GM Diagnostic Trouble Codes Self Help   2500 rpm misfire   PO300 misfire 05 2500HD   94 GMC Sierra OBD 1 Codes   2008 Silverado 6.0 cylinder 7 misfire 
Vortec 6000 6.0L V8 Sponsor
Advertise Here

Re: o2, mass air, misfire codes after new exhaust...help!!

Postby Gmrepairman » Jan 09 2014, 4:47am

What cylinders are misfiring. One bank or two. Are there any fuel trim codes. It's also best not to relearn the crank if there is a fault. It will then try to run correctly to the fault and will then cause issues when you do actually fix the root problem. These trucks were prone to intake gasket leaks when cold, broken manifold exhaust bolts causing unmetered air to enter the exhaust and effect fuel trim. Broken dipstick tubes also unmetered air and bad upstream o2 sensors not setting a code but messing with fuel trim.
Gmrepairman
Automotive Technician
Automotive Technician
Combustion on 1 piston [L2]
Combustion on 1 piston [L2]
Posts: 116
Topics: 9
Blogs: 0
Joined: Oct 15 2013, 4:12am
Location: Pa
Year: 2008
Make/Model: Chevrolet Silverado
Group Membership:
Automotive Technicians
Registered users

Re: o2, mass air, misfire codes after new exhaust...help!!

Postby CJ_03_2500HD [OP] » Jan 09 2014, 5:05am

The misfires are random between all the cylinders but since I put the tune back on it runs better but only at higher RPM's. Before I did the relearn after replacing everything, 6&8 were doing the most of the misfiring more frequently. My buddy had his scanner hooked up yesterday and we went for a drive and there were barely any misses (1 or 2 at a time) in random cylinders on both banks throughout the whole time driving but once we pulled over it got more constant in bank 2. Also the only codes coming up now are the random misfire and for o2 bank 2 upstream. I sprayed around the entire intake system with carb cleaner and the RPM's never jumped, the manifold bolts haven't been touched. The dipstick tube is also fine. Im going to replaced the upstream o2 sensor either way because its original and to eliminate a possible problem. After I replace the sensor should I do another relearn or what do you think I should do to get the truck back in the best running order?
Original Poster
CJ_03_2500HD
Firing on 1 cylinder [L1]
Firing on 1 cylinder [L1]
Posts: 10
Topics: 1
Images: 3
Blogs: 0
Joined: Jan 07 2014, 5:30am
Location: Trenton, NJ
Year: 2003
Make/Model: Chevrolet Silverado
Extra Info: 2500HD 6.0L V8 4x4
Group Membership:
Registered users

Re: o2, mass air, misfire codes after new exhaust...help!!

Postby Gmrepairman » Jan 10 2014, 3:16am

I would get the 02 replaced do a fuel trim reset and monitor those if seems straight at an idle do a relearn.
Gmrepairman
Automotive Technician
Automotive Technician
Combustion on 1 piston [L2]
Combustion on 1 piston [L2]
Posts: 116
Topics: 9
Blogs: 0
Joined: Oct 15 2013, 4:12am
Location: Pa
Year: 2008
Make/Model: Chevrolet Silverado
Group Membership:
Automotive Technicians
Registered users

Re: o2, mass air, misfire codes after new exhaust...help!!

Postby CJ_03_2500HD [OP] » Jan 10 2014, 3:53am

Im going to get the o2 tomorrow and Ill keep you posted on the outcome. Thank you.
Original Poster
CJ_03_2500HD
Firing on 1 cylinder [L1]
Firing on 1 cylinder [L1]
Posts: 10
Topics: 1
Images: 3
Blogs: 0
Joined: Jan 07 2014, 5:30am
Location: Trenton, NJ
Year: 2003
Make/Model: Chevrolet Silverado
Extra Info: 2500HD 6.0L V8 4x4
Group Membership:
Registered users

Re: o2, mass air, misfire codes after new exhaust...help!!

Postby 06MonteSS » Jan 10 2014, 6:01pm

have you gotten a new GM MAF sensor yet to replace your current one??? a bad MAF sensor would cause it to run bad, can cause misfires/codes, etc... if you haven't done that yet, then I would get a new GM maf sensor for the truck... do NOT get an aftermarket one, get the GM maf sensor that's for the truck...
06MonteSS

Image
User avatar
06MonteSS
Recognized Supplier
Recognized Supplier
Shifting into Second Gear [L3]
Shifting into Second Gear [L3]
Posts: 1267
Topics: 23
Blogs: 0
Joined: Oct 12 2011, 7:50pm
Years of membership: 2 years of membership2 years of membership
Location: CT
Year: 2014
Make/Model: ...Not an owner
Variant: SS
Extra Info: 2014 Camaro SS
Group Membership:
Vendors
Registered users

Re: o2, mass air, misfire codes after new exhaust...help!!

Postby CJ_03_2500HD [OP] » Jan 11 2014, 3:12am

I havent gotten a new MAF yet, thought about it but they're pretty expensive and I haven't had any codes for it besides one that was old before this issue. Im going to do an injector flush tomorrow and the upstream o2 because it needs to be done either way. If i continue to have this problem after that than I might just try a new MAF. This has been nothing but a damn nightmare...
Original Poster
CJ_03_2500HD
Firing on 1 cylinder [L1]
Firing on 1 cylinder [L1]
Posts: 10
Topics: 1
Images: 3
Blogs: 0
Joined: Jan 07 2014, 5:30am
Location: Trenton, NJ
Year: 2003
Make/Model: Chevrolet Silverado
Extra Info: 2500HD 6.0L V8 4x4
Group Membership:
Registered users

Re: o2, mass air, misfire codes after new exhaust...help!!

Postby masterem88 » Jan 11 2014, 6:19am

You can unplug mass air flow to see if its causing your driveability issues if you don't have access to a labscope or atleast a good scanner that can graph data. If unplugged it goes to default predetermined values based on input from other sensors.

Sent from AutoGuide.com Free App
-ASE Master Automobile Tech- Associates Degree in Automotive Technology
-Russ Moore Transmission Specialists
-Northeast Allen County Fire Department
User avatar
masterem88
Automotive Technician
Automotive Technician
Combustion on 4 pistons [L2]
Combustion on 4 pistons [L2]
Posts: 487
Topics: 5
Images: 15
Blogs: 0
Joined: Oct 06 2012, 10:47pm
Years of membership: 1 year of membership
Location: fort wayne, IN
Year: 2000
Make/Model: Chevrolet Silverado
Extra Info: K1500 Z71 5.3L
Group Membership:
Automotive Technicians
Registered users

Re: o2, mass air, misfire codes after new exhaust...help!!

Postby masterem88 » Jan 11 2014, 6:20am

Yes it will set codes running it unplugged but temporarily ignore that and drive it to see if it runs a lot better

Sent from AutoGuide.com Free App
-ASE Master Automobile Tech- Associates Degree in Automotive Technology
-Russ Moore Transmission Specialists
-Northeast Allen County Fire Department
User avatar
masterem88
Automotive Technician
Automotive Technician
Combustion on 4 pistons [L2]
Combustion on 4 pistons [L2]
Posts: 487
Topics: 5
Images: 15
Blogs: 0
Joined: Oct 06 2012, 10:47pm
Years of membership: 1 year of membership
Location: fort wayne, IN
Year: 2000
Make/Model: Chevrolet Silverado
Extra Info: K1500 Z71 5.3L
Group Membership:
Automotive Technicians
Registered users

Re: o2, mass air, misfire codes after new exhaust...help!!

Postby CJ_03_2500HD [OP] » Jan 11 2014, 7:37am

My buddy has a real good snap on scanner, Ill have to have him come with me tomorrow and check it out. Thanks guys, greatly appreciated!
Original Poster
CJ_03_2500HD
Firing on 1 cylinder [L1]
Firing on 1 cylinder [L1]
Posts: 10
Topics: 1
Images: 3
Blogs: 0
Joined: Jan 07 2014, 5:30am
Location: Trenton, NJ
Year: 2003
Make/Model: Chevrolet Silverado
Extra Info: 2500HD 6.0L V8 4x4
Group Membership:
Registered users
Next

Return to Vortec 6000 6.0L V8

 

  • Similar topics
    Replies
    Views
    Last post
  • Misfire on #6 and #1
    Internal problem?
    1 ... 7, 8, 9 by starspangled6.0 » Feb 13 2012, 10:32pm
    80 Replies
    11557 Views
    Last post by breadman View the latest post
    May 14 2012, 11:59pm
  • 9 Replies
    52 Views
    Last post by SilveradoSierra.com View the latest post
    Sep 02 2014, 12:24am
  • Misfire it seems please help
    by tazjamin » May 02 2012, 8:08am
    1 Replies
    883 Views
    User avatar
    Last post by ASTE25 View the latest post
    May 03 2012, 1:37am
  • Misfire causes?
    What would cause a misfire?
    by cntryboy081 » Aug 03 2014, 9:41pm
    2 Replies
    199 Views
    Last post by Welcher774 View the latest post
    Aug 03 2014, 10:02pm
  • 6 liter misfire!
    my 04 with 120k has had a miss fire code recently need advice!!!
    by Babbitt180 » Oct 26 2012, 2:53am
    4 Replies
    7131 Views
    User avatar
    Last post by starspangled6.0 View the latest post
    Oct 28 2012, 6:28pm
  • multiple misfire
    multiple misfire
    by smithlandscaping » Jan 11 2013, 6:07am
    1 Replies
    1230 Views
    User avatar
    Last post by ASTE25 View the latest post
    Jan 11 2013, 4:39pm

Common search terms

help back mass misfire codes exhaust still work thanks think

It is currently Sep 02 2014, 12:24am

  • Sponsor
Login  •  Register
SHOP TALK (Live Chat)
Vortec 6000 6.0L V8 Forum
Vortec 6000 6.0L V8 specific
To create a new topic in Vortec 6000 6.0L V8, click this button:
Previous topic Next topic
Sitewide News Sitemaps & Feeds

Who is online

Users browsing this forum: No registered users and 5 guests