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Air & Fuel adjustments ? ? ?

This is a discussion on Air & Fuel adjustments ? ? ? within the Computer & Tuning forums, part of the LSx Technical Help Section category; Is there a cheap alternative to adjusting the fuel & air to mix without having to get it tuned? I ...

  1. #1
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    Air & Fuel adjustments ? ? ?

    Is there a cheap alternative to adjusting the fuel & air to mix without having to get it tuned? I plan on the tune but the car backfires and idles so bad I would be scared to pull it on a trailer.

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    Senior Member mrr23's Avatar
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    dark bowling green
    2000 corvette

    no. it's controlled by the tables in the PCM.

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    12.36@109 Red on Red WS6's Avatar
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    Quote Originally Posted by popocamaro1 View Post
    Is there a cheap alternative to adjusting the fuel & air to mix without having to get it tuned? I plan on the tune but the car backfires and idles so bad I would be scared to pull it on a trailer.
    You need to diagnose why it is Backfiring and idling bad. I highly dought it is an AF problem.

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    Red
    Hummer H2-Escalade-98 SS

    so you think maybe it will throw a code if i brought it up to somewhere and they ran the check on it? i know the service engine light is already on from the o2 delete? there was an issue when we put the 99+ valve covers on because the 98 valve covers required 4 vaccum hook ups and the 99+ only provided 3 i think it was what they said so they just y-ed off the extra hose back into the loop but said as long as the vaccum is hooked up everywhere your good to go , and buy a breather and i did that. Come to think of it it may have started when I put the breather on but im not for sure. I would hate to get all the way to the tuner and him not be able to do his job because something is wrong that needs fixing before tuning and the closest tuner is over 2 hours away.

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    12.36@109 Red on Red WS6's Avatar
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    You need to have the car in the best operating condition possible when you take it in for a dynotune. You also need to update your signiture and give us a description what you have done to your car, and what lead up to the problems your having. Did you only change Valve covers?

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    Red
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    Took it to autozone and this is what it spit out

    PO171 - SYSTEM TO LEAN O2 SENSOR
    PO174 - SYSTEM TO LEAN O2 SENSOR
    PO405 - EGR VALVE
    PO443 - VACCUM LEAK
    PO300 - MISFIRE
    PO405 - EGR EVAP SOMETHING

    The guys noticed that there was no hookup for the vaccum line on the 99+ passenger side rear valve cover like there is on the original 98 valve covers so the tied some lines into others but I can not see them. Also is the LS6 PCV conversion necessary? it was not done
    ------------------------------------------------------------------------
    - G5X1 228/232 .588 .574 112 cam
    - LS6 Heads lightly ported & polished
    - Comp 918 Springs
    - ThunderRacing 7.4 Pushrods
    - LS7 Lifters
    - LS6 Intake
    - LS6 Oil Pump
    - Ported & Polished w/Bump Stop
    - ThunderRacing MAF
    - LS2 Timing Chain
    - MSD Wires
    - NGK TR55 Plugs
    - 99+ Valve Covers
    - Jet Hot L/T`s
    - TSP T/D`s
    - SLP Lid
    - T/R MAF
    - EGR delete

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    Senior Member mrr23's Avatar
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    looks like you have a nice vacuum leak somewhere. most likely the intake didn't seal.

    no, the LS6 PCV valley cover isn't necessary.

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    ok while checking and making sure everything was tight i noticed the neck on the drivers side header that the blockoff plate is on is cracked and air is blowing out of it...would that even have an effect since its exhaust anyway?

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    12.36@109 Red on Red WS6's Avatar
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    Quote Originally Posted by popocamaro1 View Post
    ok while checking and making sure everything was tight i noticed the neck on the drivers side header that the blockoff plate is on is cracked and air is blowing out of it...would that even have an effect since its exhaust anyway?
    It will cause a very big problem. You can't have any exhaust leaks before the front O2 sensors because it brings in fresh air. That is what is causing your System to lean code, the computer thinks you are lean and it is dumping a bunch of fuel to help for the false lean condition. Fix the exhaust leaks ASAP.

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    95-black & 80-blue
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    run some seafome in it and that sould get rid of some or most of the backfiring. cause i did it and the backfiring at idle stoped. do every thing on this link and see what it does.
    http://www.ls1tech.com/forums/showth...6&page=1&pp=20

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    Red
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    I Will Try Both And Post Up Thanks Guys

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    Red
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    The Crack Was Welded And The Engine Was Sea Foamed Again And It Ran Great For About 5 Min And Then Went Into A Full Auto Back Fire Mode Like I Have Never Heard It Do Just Pop Pop Pop Pop Pop Pop And I Cut It Off I Am Clueless

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    12.36@109 Red on Red WS6's Avatar
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    Quote Originally Posted by popocamaro1 View Post
    The Crack Was Welded And The Engine Was Sea Foamed Again And It Ran Great For About 5 Min And Then Went Into A Full Auto Back Fire Mode Like I Have Never Heard It Do Just Pop Pop Pop Pop Pop Pop And I Cut It Off I Am Clueless
    If it ran fine for 5 min. it sounds like it may be a closed loop problem. Could you have some data logging done?

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    Veteran 0rion's Avatar
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    yep, sounds like a closed loop problem. You need to have the car logged to see what's going on. This is just a guess but I would look at the front O2's and see if they're fouled due to being overly rich because of the lean codes.

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    Quote Originally Posted by Red on Red WS6 View Post
    If it ran fine for 5 min. it sounds like it may be a closed loop problem. Could you have some data logging done?
    not to sound dumb but how do i go about doing this? the only tuner close to here is more then two hours away and the only thing local is autozone who just has the regular code scanner. Fouled out does this mean they may be bad? So is are you also saying that everything could be hooked up tight and fine but there is something in the computer or something hooked to it thats jacked up. I really just want this thing to run right just once before i go oversees

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    12.36@109 Red on Red WS6's Avatar
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    Quote Originally Posted by popocamaro1 View Post
    not to sound dumb but how do i go about doing this? the only tuner close to here is more then two hours away and the only thing local is autozone who just has the regular code scanner. Fouled out does this mean they may be bad? So is are you also saying that everything could be hooked up tight and fine but there is something in the computer or something hooked to it thats jacked up. I really just want this thing to run right just once before i go oversees
    You may post up in the Regional Forums and see if anyone lives near you that could scan it, take it to a service center or you could buy software like Autotap and hook it up to a laptop. If you are sure your exhaust leak & vacuum are fixed then disconnect the positive on the battery for five min. then reconnect. Try running the car and if it starts backfiring again try disconnecting the Mass airflow sensor and let me know what happens. Do you plan on having it dynotuned or a mail order tune?

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    Red
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    it appears its been figured out, the guy that did the work on my car has never done anything on a 98 LS1 and when scraping the EGR and figuring out how to y off the extra vacuum line he scraped the hose containing the PCV valve which you really could not even tell was there because it was wrapped up with electrical tape and was about the same width as the hose. We took the old PCV valve and installed it inbetween the hose that runs from the front of the intake to the drivers side rear and so far no more back firing and good throttle response. I assume that because the way air flows throught the PCV valve this would have caused the vacuum leak. Thanks for everyones time and help it just goes to show pay attention to detail because despite the fact hes done 10+ installs this was his first pre 99 and he did not know it was there. I just have to get the baby tuned and beef up the drivetrain because it shifts when it wants too and gas mileage sucks.

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    12.36@109 Red on Red WS6's Avatar
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    good to here, glad you figured it out.

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    Glad your guy caught the PCV issue. You should keep an eye on your 02 sensors on the side of the exhaust that had the crack in it. Heated 02's do not hold up well when they're stuck in a rich environment. Probably not bad now but on their way out. The rear one is not so important, should get it deleted anyway. It's only purpose is to make sure the cat is working. The front one going bad though can be problematic, and effect your tune down the road. The 02 sensors are designed to last 60000 miles but 50 miles of running rich has been shown to do them in.

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    Red
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    ok will remember that and will get a new set just to be safe

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