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99 silverado 5.3 miss/jerk engine light

This is a discussion on 99 silverado 5.3 miss/jerk engine light within the Technical / Maintenance forums, part of the General Discussion category; Yep, Been searching for days on this topic via google, and almost forgot to post here and see if I ...

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    Angry 99 silverado 5.3 miss/jerk engine light


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    Yep, Been searching for days on this topic via google, and almost forgot to post here and see if I could get some insight.

    I bought a 99 silverado Z71 with the 5.3 auto 4x4 as my first big truck, in the hopes that it would last me well into the future. It has about 135k miles, and was babied for most of its life by the previous owner.

    As with any new vehicle purchase, I like to know where i am standing on maintenance, so I changed the plugs, wires, air filter, and fuel filter almost immediately to give her a brand new bag.

    For a few weeks, it drove wonderfully, but after that my engine light would come on, then go off while driving. It might be on and then go off again a day later.

    A trip to Autozone gave me a P0171 and P0174 lean code in both banks.

    Now, these codes stay on and never reset, even after being reset by my pocket scanner. I also experienced another code referencing a "small" leak with the EVAP system. This code has not returned since being cleared.

    As far as drive-ability, The truck is jerk/slip/missing at random in 4th gear with put under any strain at lower RPM's. This jerk shutters the entire truck, and seems to be worse over time. Once shifted to 3rd, it does fine.

    HOWEVER, if the truck is geared down, say 1st or 2nd, and allowed to rise to a higher RPM, it backfires erratically, not with any specific pattern. This also gets worse from day to day.

    At first, I thought, tranny. I know the GM's are notorious for tranny issues. So I stupidly flushed the tranny and ran some TransX through it. So far, it shifts great, except for the miss, or slip, or jerk.

    I have read issues similar online, and no one seems to post their fix. Everyone starts by checking basically everything that can be checked.

    I am curious as to if this is a common issue, or if anyone else has experienced it here and knows where to start. I may have missed a post but I am so sick of looking through documents online and in forums and getting nowhere, I am turning to some guys that just might get me somewhere.

    I love this truck, it's my first, and I love Chevy. I really want to repair the issue and keep on trucking for years to come, but I am an expecting father, and I can't afford to piss thousands away on a maybe when I can probably fix the problem without a mechanic.

    Any help is greatly appreciated.

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    Re: 99 silverado 5.3 miss/jerk engine light

    Update:

    Spent several hours today working the truck over.

    Checked Plugs/Coil/Wire sparks, generally good on all.
    Replaced MAF sensor, good readout on scanner tool
    Cleaned fuel rails and injectors, both banks
    Checked Compression, fine
    Checked fuel pressure, best I have seen
    Vacuum hoses seem to be good, a sucking is present.
    FPR has no fuel around hoses, and all fittings are clean.
    Found 1 cracked plug, replaced, no fix.
    Ran Seafoam through rails and tank, no better
    Started to replace Intake Gaskets, but didn't see signs of wear or gas leakage around seals from front of intake to head.


    To recap, the truck is showing P0171 and P0174 codes, and missing under mid/high throttle when under a strain. No 300 code, or cylinder missfire codes have been thrown yet.

    Truck also sounds like it's backfiring in high RPM's under the hood, probably from the intake side.

    I am really not sure where else to look at.

    Has anyone had similar issues on a 99 5.3 Vortec, or have any idea why i am getting lean codes on both banks? Is there another sensor I need to test/replace. Read that the Knock sensors and coolant sensors could help this lean situation, but posts are on older models.

    Please help.

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    Re: 99 silverado 5.3 miss/jerk engine light

    Sounds like its time for a fuel pump. Check the volume of the fuel being sent to the engine. A good fuel press. gauge should have a bleed off button if you bleed of some pressure and it stalls than its not getting enough fuel. Try drive with the gauge on it and watch the pressure at wot and under a good load it should drop very little if any.
    Last edited by KUGS; 01-05-2010 at 11:55 PM.
    2001 silverado 5.3 flowmaster with dual outlet dumps black on black with black windows

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    Re: 99 silverado 5.3 miss/jerk engine light

    My dads 2003 with 4.8L had both of the same codes and it turned out to be the intake gasket leaking in air.

    1999 Chevrolet Silverado 1500 RCLB
    6 inch Fabtech lift - 315 75 16 Terra Grapplers - 4.3 L V6 Vortec. Flowmaster single exhaust - K&N High flow air filter

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    Re: 99 silverado 5.3 miss/jerk engine light

    Yeah, I checked the intake gasket, from the outside, where the injectors enter the intake, it's dirty and shows no sign of leaking. Then I read tonight that the intakes can leak from the inside, making it hard to detect without replacing.

    I also read over 300 threads involving backfires, timing, and missing, and found that the knock sensors are primarily responsible for moving engine timing at high RPM's to quiet the engine knock, I wonder if they are faulty or causing my backfire at higher rpm's? I don't have any codes for misses or knock sensors, its baffling.

    As for the fuel pressure, it was 56, held at 55 idle, and under throttle it didn't dump much at all, spiked up actually. I didn't drive it with the gauge connected however. My mechanic said it was the best he had seen on a 99.

    The miss at half throttle is what's annoying me. I want to blame the converter so bad, but it just doesn't feel like that's the issue.
    Last edited by Stumasters; 01-06-2010 at 11:04 AM.

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    Re: 99 silverado 5.3 miss/jerk engine light

    I threw the P0171 and P0174 code a week ago on an '02 5.3L with 100K. The truck would start strong, but after just a few seconds would begin to lope and idle very poorly until about 5 minutes went by. Never noticed that until the outside temps went below 20.

    I didn't have a scanner handy at the time so I replaced the PCV and checked my intake plumbing (came with an Airaid). The intake was loose so I cinched it all back down and the SES light went off. I cleared the codes, but it was still idling poorly for a few minutes. Last night I cleaned the MAF and fired it up. That just might have fixed it, I'll know in about 20 minutes.

    All this doesn't help much, just wanted to share my P0171 and P0174 code saga. So many possibilities with these two... I doubt I'm done with it, but the codes haven't shown back up yet.

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    Re: 99 silverado 5.3 miss/jerk engine light

    Yeah, I really don't like chasing rabbits on a vehicle. This is my first American vehicle in years, and I hate to say, I am not having trouble seeing why they are in such trouble.

    However, I do love my truck, and I have always valued the Chevrolet pick-up. They are some nice trucks, and will hold up to anything, but engine problems just really tick me off.

    I am going to try and see if my intake is just a little loose today, but its about 20 degrees out there, and windy. It may just have to wait until next week. I just hope I can get all the input possible before then. It was the cold weather that brought out my issues.

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    watch for me in TRUCKIN' dubnutts's Avatar
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    Re: 99 silverado 5.3 miss/jerk engine light

    so your crusing in 4th gear and give it a little gas and it jerks enough for you to feel it and then it accels fine??? cause thats what mine does but mine has 172k and i would like to know whats wrong, im gonna flush my trans soon and replace the filter and main gasket as well and i hope it fixes the jerk... did you replace the filter when you flushed yours????

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    Re: 99 silverado 5.3 miss/jerk engine light

    I don't know for sure if the guy replaced the filter, i would assume he didn't, because it was one of those 1 hour flushes. I also ran TransX through it, and it does shift better, but because my jerk was not tranny related, it was kind of a waste of time.

    I have heard of jerks like your experiencing also comming from sloppy U joints. In other words, you might have some slop, and when you feel a pop, it's the slack catching up with the driveshaft. Thats a pretty easy thing to fix.

    The jerk I am feeling now is just a hesitation, missfire, or lean condition causing the engine to just drop power little by little about mid throttle, and backfire at high throttle.

    It's probably the worst engine issue I have ever tried to diagnose.
    Last edited by Stumasters; 01-07-2010 at 04:38 AM.

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    Re: 99 silverado 5.3 miss/jerk engine light

    My 99 nbs has the same codes. My fuel pressure only reads out at 50 witht he key on though, which is a bit low according to the mechanic. I'm going to be replacing the fuel pump before long and hopefully that takes care of the issue. I replaced plugs, wires, and fuel filter and it gave me a bit better fuel economy, but did not get rid of the codes.

    My problem was a lot like yours where the SES light would come on then go off and then eventually just stayed on solid.
    1999 Silverado LS 4x4 Z71 w/ 5.3L

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    Re: 99 silverado 5.3 miss/jerk engine light

    I honestly think you have a vacuum leak. Or a bad MAF. 90% of a lean code can be either of those two. Try spraying carb cleaner around the intake gasket and make sure all vacuum hoses are tight and in good condition. Also try disconnecting the MAF sensor when its cold to see if it smooths out. Just a thought...

    Edit: Forgot to ask, did you actually check the fuel flow? That's the next important thing from fuel pressure. Make sure the fuel filter is clean as well.
    Last edited by jpchevyk20; 01-07-2010 at 07:35 PM.

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    Re: 99 silverado 5.3 miss/jerk engine light

    To be honest, I am not sure how to see fuel flow, really. Do you just use a standard gauge and watch it while driving?

    The fuel filter was replaced about 5 thousand miles ago, and it was probably the first time it has ever been replaced, and the MAF was just replaced, and appears to be functioning correctly according to my scan tool. So I am leaning towards the vacuum leak. The outer seals on the intake seem to be solid, but I am not sure about the inner seals around the block.

    I plan on swapping the gasket next weekend, and seeing where that puts me. About 3 people that work on GM's have told me the seals are most likely my whole problem.

    I will have to report back once the seal has been repaired, and hopefully that will fix me up. If not, it's a one by one search of every sensor on the truck with a tester until i come up with something.

    I thank you all for your input thus far.

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    Re: 99 silverado 5.3 miss/jerk engine light

    Its pretty easy, just need to find the service port and bleed the fuel out and measure how much fuel comes out in a certain time. Not sure what the specs for that would be. Its also easier with the proper tools. Well I hope you find what your chasing for. Also it may be worth taking it to a diagnostic shop and having them run a live scanner on it and see what they say. It may cost you a few bucks but it might save a few and give you piece of mind. I always like to know exactly what i'm dealing with and try to get as much info as I can. Wish you luck!

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    Re: 99 silverado 5.3 miss/jerk engine light

    same symptoms replaced my intake gasket lastnight. took me about 6 hours with 2 trips to the parts store. i needed a small piece of hose that i cut out of frustration coming from the bottom of the tb to the right and another time for a set of quick disco tools for the fuel lines. plus 45min was trying to figure out the electric connector on the injectors. i found it easiest to pull the gray thing all the way up and out then pushing in the clip and removing it. have fun!
    -quardt

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    Re: 99 silverado 5.3 miss/jerk engine light

    I've done intake gaskets 3 times and it's not bad at all. Here's a few things I would suggest doing. First remove the the fuel rails, crossover, and injectors as one assembly. This will allow you to unbolt the purge solenoid from the front of the intake without disturbing the tube attached to it. Then just tie the solenoid up out of the way, taking care not to kink the tube.

    Also, while your intake is off don't forget to clean out your rear knock sensor hole and connector. Then seal up the knock sensor grommets and build an RTV "dam" around them with an opening in the back for water to drain out.
    99 Silverado ECSB 4X4, LQ4, Patriot Stg. 2 243's w/ 59cc chambers, TR224-112, Pacesetter LT's, Nelson tune, FLT Lvl 5.5, PI 3400, UD pulley, 160* t-stat, E-fans, 6'' Fabtech lift, 3'' body lift, 37'' XTerrains, 4.56's, 4'' shackle flip 13.3 @ 99mph on 37's or 13.0 @ 101mph on 31's

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    Re: 99 silverado 5.3 miss/jerk engine light

    Yeah, the injectors were a Pita. I had a round with the first one, broke one of the grey tabs, but it still holds tight, so I didn't really care about that.

    Thanks on the tips for the gasket as well. My friend has changed a few of them, and he is going to help me next weekend. I will jot that process down and make sure we do that. He seems to think you can replace the gaskets without really taking the entire intake off, just raise it up high enough to replace them.


    As for the knock sensors, I still can't figure out how to seal them and leave a dam. I get the concept, I just wish I had come close-up pics of someone else who has done it. It's hard for me to understand where the slot at the back should be to let water out, and how to make it. Anyone have some links or pics to a very detailed image?

    Thanks!

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    Re: 99 silverado 5.3 miss/jerk engine light

    when i did it lastnight, i didnt remove the fuel rails. left em on just unhooked the fuel line quick connects. make sure you pull the intake off. the amount of crap under there is unreal. if you just slid it in you surely wont get a good gasket seal. no hints on the dam. basically just a 1/4" bead of rtv around the plug with a 1/4" gap on the side towards the back.

    bigbob: could you tell me what the purge valve connects to? after it runs around the back of the intake i lost the connection and cant find anything to plug it into.
    -quardt

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    Re: 99 silverado 5.3 miss/jerk engine light

    Quote Originally Posted by quardt View Post
    bigbob: could you tell me what the purge valve connects to? after it runs around the back of the intake i lost the connection and cant find anything to plug it into.
    Just follow the fuel lines back to the first holder that's bolted to the trans bellhousing. The connector holds three lines, two fuel and one for the purge valve.(it's actually kinda offset to the middle of the driver side cyl head) That's where the tube connects to.

    And for those having trouble with the gray injector retaining clips, I just pull them completely off. Then replace them when you plug the injectors back in. I actually left them off my '99 and never had a problem.
    Last edited by bigbob6988; 01-10-2010 at 11:37 AM.
    99 Silverado ECSB 4X4, LQ4, Patriot Stg. 2 243's w/ 59cc chambers, TR224-112, Pacesetter LT's, Nelson tune, FLT Lvl 5.5, PI 3400, UD pulley, 160* t-stat, E-fans, 6'' Fabtech lift, 3'' body lift, 37'' XTerrains, 4.56's, 4'' shackle flip 13.3 @ 99mph on 37's or 13.0 @ 101mph on 31's

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    Re: 99 silverado 5.3 miss/jerk engine light

    Update ::::

    Well, today we ripped it down again, checking every line, sensor, and part. Saw nothing.

    Replaced the Intake Gaskets, did another fuel pressure check, this time while driving.

    Fuel pressure rests around 55 engine off, same with engine on, and runs up to 60 while driving, or when opening the throttle fast.

    Seals were in decent shape, but showed signs of wear, seems to have better vacuum now, but still lean, both banks.

    ALSO, noticing a pattern with my number 2 plug, the insulator is cracking about half way down the plug and the cracks stop before it reaches the other end, in other words, the crack is centered on the insulator, top part of the plug. Tonight, the one I pulled out had 2 cracks, right next to eachother, causing my missfire I am sure.

    Problem is, I can't figure out whats cracking them, and whats making the damn engine run lean.

    Out of ideas, anyone else????

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    Re: 99 silverado 5.3 miss/jerk engine light

    bigbob: thanks. i thought that was the only place it could go but the previous owner must have disconnected it. for some reason there was a rubber cap on top of that line. i removed the rubber cap and reinstalled the line.

    unfortunately i've started throwin the codes again. i'm gonna add a external inline fuel pump to bump up my somewhat low pressure and see if that helps. otherwise i think im gonna have to bite the bullet and take it to a dealer. only other thing i could think of is a worn out 02 sensor.
    -quardt

 

 
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