Chevy Silverado 5.3 lean fuel code

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Thread: Chevy Silverado 5.3 lean fuel code

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    Chevy Silverado 5.3 lean fuel code

    I have a four wheel drive Chevy Silverado 1500 with a vortec 5.3 motor in it. The truck has 59,800 miles on and was manufacturer in Canada as I found out this makes a difference on the 02 sensor. I have been fighting a lean fuel code for the past 2 months and can't seem to get rid of it.

    I have change out the following parts:
    1) air filter
    2) fuel filter
    3) Idle air controler (truck was pulsating on cold start ups until it reach operating temp.)
    4) plugs
    5) wires
    6) both upstream 02 sensors.

    I have taken it to a repair shop and they spent an afternoon trying to come up with something wrong with it and they can't. They stated the vacum was good, they smoke the engine and could find no leaks around the intake or injectors. They shut off individual pistons and all the injectors seem to working. They did state as they have no way of testing the flow of the injectors. They check the other sensors and found no issues.

    I have watched when the light comes on for the past 3 times and it is always when the truck reaches 180-185 degrees. Friday after they reset the computer the light stayed off till this moring on my way to work.

    So in summary my question is what is my next step. The repair shops says it might be the computer going or I need to take it to a dealership to get a complete computer flash. They also recommended a motor vac to clean the intake injectors and intake.

    Any help would be greatly appreciated.

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    Re: Chevy Silverado 5.3 lean fuel code

    If someone is working on an emissions problem without printing and following the GM trouble tree which explains step-by-step the most cost effective and likely way to find the problem they are wasting your time and money.

    Take it to someone who will. Quit guessing.

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    Re: Chevy Silverado 5.3 lean fuel code

    It needs a set of intake gaskets.Very common especially when it gets colder out.It probably also runs rough on cold starts also.The gaskets are like $90 for the set.The intake is dry so no coolant will leak out.Any compentant shop should of been able to handle this for you.
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    Re: Chevy Silverado 5.3 lean fuel code

    Quote Originally Posted by 73ChevelleSS View Post
    It needs a set of intake gaskets.Very common especially when it gets colder out.It probably also runs rough on cold starts also.The gaskets are like $90 for the set.The intake is dry so no coolant will leak out.Any compentant shop should of been able to handle this for you.
    exactly. and being lean that long, it probably has caused a misfire. if it has then there may be more damage, such as an o2 sensor, and possibly catalytic converter. main thing to look at is fuel trims on both banks, compare them, then watch them as you spray carb cleaner around the intake gasket area.
    also you can watch your 02 sensor voltages, make sure they are switching high and low, and not fixed at one location.
    There are no stupid questions, just stupid people.

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    Re: Chevy Silverado 5.3 lean fuel code

    Thank you for your response. Would you recommend replacing the intake right away as well incase of warping. I have seen this on other forums. The shop were I took say they have an aftermarket Doran part#165-813 that replaces the stock one. Has anyone used this?

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    Re: Chevy Silverado 5.3 lean fuel code

    i would stay with the GM parts, when you get into the aftermarket stuff, sometimes it causes problems. but thats on certain things, i would check into them a bit deeper, aska round about them, i know dorman makes a nice set of intake gaskets and a plenum for those trucks, may be what your talking about? anyways, thats the only aftermarket company i would trust for things like that.

    it is possible the intake plenum may be warped. most of the time, you can get away without having to replace the plenum. take a straight edge to it, then use feeler gauges to see if it is warped. if its warped, get a new plenum and gaskets.
    There are no stupid questions, just stupid people.

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    Re: Chevy Silverado 5.3 lean fuel code

    Yes that is the name of the part. It comes with the the gaskets and intake for around $300

    I found the part on the internet and your are correct it is the plenum and gasket set Dorman Part #615-183

    I quess my thought is if I have them tearing it apart anyway why take the chance on a part that may cause the problem againg
    Last edited by VodooRacing; 12-16-2008 at 08:16 PM.

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    Re: Chevy Silverado 5.3 lean fuel code

    I doubt the intake is warped.Just have them check it with a staright edge.Each port needs to be checked though.
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    Re: Chevy Silverado 5.3 lean fuel code

    Quote Originally Posted by 73ChevelleSS View Post
    I doubt the intake is warped.Just have them check it with a staright edge.Each port needs to be checked though.
    Some warpage is ok on plastic intakes and the gaskets are redesigned from gm.I doubt it needs a manifold tho

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    Re: Chevy Silverado 5.3 lean fuel code

    Well I think the problem is solved. I had the truck in the shop Friday and had both the gasket and intake replaced with a Dorman intake and gasket kit part #615-183. I had to travel this weekend and the truck ran great. It sat out saturday night in -5 below weather and started right up an idled great. I want to thank everyone for their help with this problem. I do have the old intake and will be checking for warping. The gasket did look terrible though.

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    Re: Chevy Silverado 5.3 lean fuel code

    I'm having the same problem, when I took the truck to the dealer the first thing they said is that it's the intake manifold... I expected this since I'm a girl, but since I've been reading this post you guys gave me some info to throw at them... so I asked "how do you know it's the $500 manifold and not just the $30 gasket set?" They came back saying they would check the gasket set before replacing the manifold.

    My question to you guys... how do I know if they are going to rip me off with a $1000.00 for a whole new manifold if it's the gasket set?

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    Re: Chevy Silverado 5.3 lean fuel code

    Quote Originally Posted by sschafer View Post
    I'm having the same problem, when I took the truck to the dealer the first thing they said is that it's the intake manifold... I expected this since I'm a girl, but since I've been reading this post you guys gave me some info to throw at them... so I asked "how do you know it's the $500 manifold and not just the $30 gasket set?" They came back saying they would check the gasket set before replacing the manifold.

    My question to you guys... how do I know if they are going to rip me off with a $1000.00 for a whole new manifold if it's the gasket set?
    First off the gasket set is $100,not $30.When they remove the intake they should check each port for warpage.If there is any warpage they are gonna tell you it needs an intake.I doubt any one is trying to "rip you off".
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    Re: Chevy Silverado 5.3 lean fuel code

    Does a mechanic just look at the codes to determine or is there a way they can check around the intake manifold for leaks?

    Dealer is saying it could also be the fuel filter or fuel pump as well. So I'm changing the filter today but just going around the truck and guessing what the problem is just by going off the codes seem to be racking up $$$.
    It's a 4.8L

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    Re: Chevy Silverado 5.3 lean fuel code

    yes, we have ways to determine what is the root cause. other items you can look at is for other codes, such as a p0300, for engine misfire. if you have 1 bank of cylinders that are misfiring at times, then most likely its an intake leak, or cat, or exhaust manifold leak. depends on a few things, you just have to have experience with dealing with them to know what exactly your looking for. sometimes a injector can cause it, but not normally on a full bank of cylinders. fuel pump or filter would not cause a single bank misfire, nor would an ignition issue, or a fuel injector, unless they are all tied together somehow and that entire item messed up. also, the type of engine has to be examined, all engines are different, some operate the same as others, depends on alot of things, if its coil on plug, or near plug, or if it has the cassette style ignition, or a distributor, just things like that are all things that need to be taken in consideration when diagnosing misfires and other check engine light issues. or any drivability issues, for that matter.
    There are no stupid questions, just stupid people.

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    Re: Chevy Silverado 5.3 lean fuel code

    This is bringing up an older post, but I am also experiencing this issue with my 99 5.3 liter.

    When I bought the truck this year, used, it ran like a top. No problems experienced at all. So like any new owner, I did a tune up, changed plugs to the GM irridium plugs, fuel filter, air filter, and wires to autolite wires.

    About a week or two later, the engine light would come on, and then off again while driving. I took it to autozone and had it computered, and it showed a P0171 and P0174 code. Their print out suggested the MAF was bad.

    After putting off the repair for a week, and having the light remain on, I swapped my MAF for a rebuilt MAF from autozone with a 1 year warranty. The truck almost idled worse right on the restart after the swap.

    About 2 weeks later, while driving, I began to notice a jerk, or hesitation in engine control in 4th gear when under a load, ie: driving up a hill. Also, when winding the engine out, 3.5k plus in RPM, it seems to backfire under the hood, not sure where.

    No missfire codes have been seen, but 1 EVAP *small leak* code popped a week ago, which I have heard could be a loose fuel cap.

    The codes were reset, and not the 171 and 174 codes still persist.

    I purchased a Felpro *red* intake gasket seal after reading all about the intake issues, but after looking close the other day, the gasket on the truck appears to be solid, at least on the visible outside around where the injectors enter the intake. No gas or air leaks spotted.

    I have cleaned the injectors in bank 2, checked all hoses I can see, checked plugs, and checked the coil sparks. Fuel pressure seems to hold around 54-56 in all situations, compression appeared good.

    Watching the sensors on a handtool seemed to look good as well, MAF and O2's are functioning as they should.

    I am lost. I can't afford to dump a ton of money into the truck not knowing what will fix it. Does this seem like it's just an interior intake gasket leak, or something more critical?

    I don't want to destroy my cat's by driving lean. Any help is appreciated. I am reading close to 100 posts a day but having a new thread with current advice sure helps in my decision making.

    Stu

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