Jump to content

07 Silverado Classic Shudder At Idle.

mbritnell

By mbritnell
in Ask A GM Technician

Recommended Posts

mbritnell Enthusiast

mbritnell

Posted
Posted

The truck is a 2007 Silverado Z71 Classic, 77,000 miles, with 5.3l flex fuel and after warm up it has what seems like a miss fire or shudder. It doesnt do it when cold and I dont have a check engine light. It has progressively gotten worse in the last 10,000 or so miles. Before I go and change the plugs I was wondering what it could be. Thanks in advance.

Nytemare Senior Enthusiast

Nytemare

Posted
Posted

Could be your O2 sensors going out...they give a little stumble (usually the forward ones) before they throw a code.

 

My money would be on a dirty MAF if you haven't already cleaned it...which would make sense with it not doing it cold.

Nytemare Senior Enthusiast

Nytemare

Posted
Posted
Thanks again for the help. I will clean it tomorrow and report back.

Its a cheap fix...and something easy to start with right...yeah get back with results...

after this I would clean the intake manifold internals and Throttle body...you can do this with a product called Seafoam, or you can bring it to the dealership, they have a tool to clean it. Seafoam is like 12 bucks a can....dealer is like 120 for the service....but its a very good service. Another thing you can do also if you haven't done it in a while, run a tank of fuel with some injector cleaner...like techron...in it.

mbritnell Enthusiast

mbritnell

Posted
  • Author
Posted

I have used the sea foam before but not in this truck.

As far as the injector cleaner, I usually run the Lucas injector cleaner every oil change. I dont know if it does any good or not though.

Nytemare Senior Enthusiast

Nytemare

Posted
Posted
I have used the sea foam before but not in this truck.

As far as the injector cleaner, I usually run the Lucas injector cleaner every oil change. I dont know if it does any good or not though.

I use the same stuff....have for 7 years now...on several vehicles...its never let me down. On a friends Blazer (4.3) the injectors were so gummed up it would die in the driveway. We tosses a small bottle in with about 5 liters of fuel and just let it run there...with in about 30 seconds it ran noticeably better...after a quick drive on the highway we tossed a new tank of fuel in it, it hasn't stalled after. We than used a can of TB cleaner on it to make sure everything else was clean too...would have Seafoamed it....but nowhere I am from sold Seafoam than...they do now though.

 

That's proof enough for me that it works.

But yeah...maybe a little Seafoam in the intake will help smooth everything out too.

mbritnell Enthusiast

mbritnell

Posted
  • Author
Posted

Well this morning I cleaned the MAF and the throttle body and now have a additional problem. The truck now idles up higher than it used to at start up, no matter whether it is cold or at normal operating temp. Then after a few seconds it sharply falls back to normal rpm. Then when coming to a stop while driving it revs up enough for me to have to apply the brakes harder than usual and then once stopped the idle returns to normal. Please tell me what I did wrong.

jro909 Senior Enthusiast

jro909

Posted
Posted

my 04 5.3 with 110k on it has what it feels like is a misfire or shutter, no lights or codes at all...somebody told me its the ethanol they put in gas now a days...i'm going to try my mechanical shrink's(nytemare lol) hes rather well versed in GMTs

Nytemare Senior Enthusiast

Nytemare

Posted
Posted
Well this morning I cleaned the MAF and the throttle body and now have a additional problem. The truck now idles up higher than it used to at start up, no matter whether it is cold or at normal operating temp. Then after a few seconds it sharply falls back to normal rpm. Then when coming to a stop while driving it revs up enough for me to have to apply the brakes harder than usual and then once stopped the idle returns to normal. Please tell me what I did wrong.

Did you make sure things were good and dry??

The ECM is just re-learning the MAF readings and adjusting fuel trim...you likely will have to get it into closed loop mode...usually 15 min on the highway at 60-70MPH will do this or it should settle out in about 25 miles or so.

Archived

This topic is now archived and is closed to further replies.

Go to topic listing

  • Recently Browsing   0 members

    • No registered users viewing this page.

  • Forum Statistics

    250.4k
    Total Topics
    2.7m
    Total Posts

  • Member Statistics

    342,840
    Total Members
    8,960
    Most Online
    appletrav
    Newest Member
    appletrav
    Joined

  • Who's Online   0 Members, 0 Anonymous, 401 Guests (See full list)

    • There are no registered users currently online

  • Latest Articles

  • Posts

    • newdude
      2 speed transfer case optional now?

      By newdude · Posted

      This is a 1/2 ton thing ONLY.  All HDs 2020-2026 have the two speed transfer case, with Autotrac as an option.     1/2 tons 2019-2026, regular 4x4s come with a single speed case (no 4LO!), and trucks with Z71 ordered, or all Trail Boss trucks come with the 2 speed case.  2 speed case is also an option on WT, and is also standard on High Country.  
    • newdude
      Different requirements for oil filters?

      By newdude · Posted

      2013 5.3 still to this day calls for the PF48 filter.  Which as a 15psi bypass pressure.     There is a TSB, 17-NA-157 that talks about the PF-63 and PF-64 filters which have a higher bypass rating of 22psi.    TSB HERE - temp.xml   "Beginning in 2012, the oil pumps began to regulate main gallery feedback instead of pump out pressure. This means that the oil pump now does not begin to regulate until pressure is built up to the main gallery. This change reduces the amount of time it takes to provide oil to the engine bearing and lifters during extreme cold start conditions.  Main gallery feedback oil pump control systems are present on the following engine families which use Spin-on oil filters: Small Gas Engine (SGE), Large Gas Engine (LGE), High Feature (HFV6) Gen2 and Small Block Gen5 gasoline engines. These engines with the main gallery feedback oil pump control systems are factory built with an ACDelco® oil filters"   It also calls out what engines use those filters.  The gen 4 small blocks were not on that list (LMG, LC9, L9H, L92, L94, L20, L96).  Gen 5 small blocks use the higher pressure filter.          That all said...   Your 7045 Napa filter is the PF63 equivalent, with 22psi bypass.  You are already using the higher bypass pressure filter.  You CAN keep using it, you don't technically have to use it though.  
    • Grumpy Bear
      Different requirements for oil filters?

      By Grumpy Bear · Posted

      Do you know WHY the filter relief setting was increased to 22 psig?    When the new system goes into the second stage the pump volume ramps up considerably. It was found that the 15 psi filter bypass setting put the filter in bypass on a warm engine when the second stage was activated. Raising the filter bypass setting forced the filter to do what it designed to do. Filter. Preventing debris from circulating during high load, high rpm operation.    So next question is how did GM find this out? VLOM/lifter failures and a deep dive by Melling Corp.    Last question. Is it required? Look at it like this; a motor may be equipped with a rev limiter. But it only works if the set point in reached. That 22 psig setting only matters if the pressure differential across the filter media exceeds 15 psig during normal warm operation. Second stage kicks in around 3000-3500 rpm.    I can't answer your question because I don't know you and how you use the truck. But I think there is enough information here to let you decide for yourself. 😉
    • Coastie05
      give me some tips to make my truck look better

      By Coastie05 · Posted

      Go back to OEM wheels. 
    • newdude
      2020 Trailboss 6.2 replacement

      By newdude · Posted

      Probably not their first rodeo, so it should go as planned most likely.  Typically the service manager or tech doing the swap will put some seat time to shake it down after they get it all put back together.  We usually put 50-100mi before we hand them back so if something happens, its not after you get it.  A coolant leaks, oil leaks, a ground left off or loose, vibration, etc.     The new engines so far have been good?  There's been a couple that have popped out there again (the replacement engine) but most have been okay.  

  • GM-Trucks.com Clubs

  • Popular Contributors

×
×
  • Create New...