In this video I show you how I diagnosed a poor running 2001 GMC Yukon when the engine is cold. This is a very common problem on all GM V8's. The lower intake manifold gasket will always leak worse when cold and tend to seal as the truck warms up. -Enjoy!
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50 thoughts on “Rough running only when cold – chevrolet / gmc 5.7 vortec”
  1. Avataaar/Circle Created with python_avatars Jim Gordon says:

    That was very informative. Thanks. I’m not sure my problem is intake gaskets, but it’s a possibility.

  2. Avataaar/Circle Created with python_avatars Wilford Brumly says:

    I know this is seven years old, but my 94 has a bad backfire at start in the winter..( upper midwest)it goes away after it warms… definitely going to replace the intake gaskets

  3. Avataaar/Circle Created with python_avatars sam bitar says:


  4. Avataaar/Circle Created with python_avatars Jorge Perez de Prado says:

    You are a beast!!! My 5.3 just started down this. So I'm getting new intake gaskets and knock sensors while I'm there. 👍👍👍

  5. Avataaar/Circle Created with python_avatars Cam Reed says:

    good video thank you

  6. Avataaar/Circle Created with python_avatars walt says:

    Thank You you the man! simular problem on a 270k engine

  7. Avataaar/Circle Created with python_avatars Corsairforu says:

    My LS1 Trans Am just started this sort of trouble, sometimes it felt as though I was taking off in 3rd gear, tonight it threw the misfire I.E. Flashing SES Light. will spray the Brake Clean on intake tomorrow and look at vacuum lines.

  8. Avataaar/Circle Created with python_avatars James Barlow Jr. says:

    Is there a link for this video for the intake manifold gaskets? Thanks.

  9. Avataaar/Circle Created with python_avatars Steve Perrett says:

    I have the same problem on a 1994 5.7 gmc sounds like intake manifold, good older video

  10. Avataaar/Circle Created with python_avatars Elroy Jetson says:

    Got to do one right now

  11. Avataaar/Circle Created with python_avatars John E. Carr says:

    Another great video.

  12. Avataaar/Circle Created with python_avatars Steve Shoemaker says:

    My sierra is doing the same thing, but with my back yard mentality, I would check for loosened manifold bolts be for I would dig into that bag of worms,

  13. Avataaar/Circle Created with python_avatars Glen Hill says:

    I like watching your videos' on many stuff on trucks. do you have any videos on or around 95' chevy 3500 5.7L AC electrickel issues? hence power to relay? not power from controller. but constant power to relay?

  14. Avataaar/Circle Created with python_avatars P Thomson says:

    I won't stop saying it, I really pray Eric becomes a teacher as he would create a whole new class of technicians that would go on to affect others.

  15. Avataaar/Circle Created with python_avatars Trevor Mievre says:

    Why would the same vehicles idle instantly smarten up when the MAP is unplugged? New map sensor didn’t help. Bad Temp sensor?

  16. Avataaar/Circle Created with python_avatars Antonio says:

    Hello, is there part two of this video? I have the same problem and I want to corfim. thank you.

  17. Avataaar/Circle Created with python_avatars robert hatch says:

    my 03 has been doing the same setting up to do intake gaskets thanks

  18. Avataaar/Circle Created with python_avatars Nick says:

    You sound like you're from Maine

  19. Avataaar/Circle Created with python_avatars Benjamin Fuller says:

    My 5.3 stft to 50 cold and 25 hot but it runing find no missfire and great idle both bank same

  20. Avataaar/Circle Created with python_avatars T. Farris says:

    Could this happen on a Ford Mustang vehicle?

  21. Avataaar/Circle Created with python_avatars ziolupo65 Cor says:

    Thanks for your videos ,help me a lot in the last 2 years with 3 Gm . I have similar problem with 5.0 vortec ,high idle when cold , different tps same problem, ECT ,EGR MAF IAC new ,5V reference good everywhere,intake gaskets new ,no leak at all ,speed sensor new , High IAC count when i have problem sometime also with closed loop .Any IDEA??

  22. Avataaar/Circle Created with python_avatars wonderer1983 says:

    My '00 Silverado 4.8L hesitates WICKED, but is almost ALWAYS isolated to cold starts (ie, first or second hard acceleration after a cold start). It's winter now so it's worse. New manifold gaskets, no leaks. New plugs and wires. New fuel pump and FPR. I'm leaning towards semi clogged catalytic converters. I legit can't see it being ANYTHING else. Plus, wouldn't this be a cause during colder temps? As the cats warm up, they perform near optimal condition. Never had any CEL's so that's worth noting.

  23. Avataaar/Circle Created with python_avatars J Hulette says:

    Logged into my wife's YouTube account but just want to say thank you for this video… have a 1994 K1500 Suburban.. Coming from Arizona to Indiana, we didn't really have this problem til we got here in colder weather.. same problem.. idles up to around 12-1300 at cold start and within about 10 seconds, idle becomes sporadic… Dropping way down to 400 or so then bounces around for about a minute or so before smoothing out to idle consistently at about 1300 til it reaches running temp and drops down to a steady 600 rpms..
    Have checked vacuum lines, changed plugs, wires, distributor, cap, rotor, fuel filter, mass air sensor… Pulled the IAC but it was pretty clean and working properly.. pulled the EGR to clean which was also very clean and working properly… TBI cleaned and functioning properly.. was wondering "WTF?!?!?!"
    FINALLY came across this video…. So now I will do some more testing… I'm betting I will be changing my intake manifold gasket next 🤣🤣

  24. Avataaar/Circle Created with python_avatars JoJo NoNo says:

    Was definitely leaning toward a mechanical issue on my '91 5.7L C1500 since there were zero codes showing. I could create codes by disconnecting things so the ECM is good. Only weird thing on some or most engines is that the temperature switch on the intake manifold doesn't set a code in the ECM. I finally went outside early cold morning and was going to do a stone cold engine vacuum test since hot engine was perfectly normal. No vacuum issue at all but idle seemed low for a cold engine. So, I decided to pull the plug off of the temperature switch. Idle shot up to what you would expect on a cold "open loop" engine. Plugged it back in, idle dropped. Pulled it off, idle shot up. Plugged it back in, idle finally stayed high on stone cold engine. Ah-Ha! My 29 year old temperature switch was sticking in the "closed loop". That's why it ran perfectly all summer and became hard to start in the cold months. Heard other people mention that the temperature switch on various model cars and engines do not set a code when they experience same issue. Maybe I can sell my antique temp switch to someone who lives in Florida? Ha-ha!

  25. Avataaar/Circle Created with python_avatars Hola! Austyn Burfeind says:

    Kind of disappointed that I was going to see some tbi troubleshooting from a suburban or at least a 5.7. but instead I get a video about a 5.3

  26. Avataaar/Circle Created with python_avatars Eduardo Rivera says:

    Them old videos where better normal acting than this new ones..more believable lol

  27. Avataaar/Circle Created with python_avatars chek pierce says:

    Mine is the complete opposite runs perfect until engine warms up n then I have a rough idle. Random cylinder misfire, running lean,

  28. Avataaar/Circle Created with python_avatars Frankie Reed says:

    You the truth

  29. Avataaar/Circle Created with python_avatars Kevin R says:

    Hello, I can not find the answer to this anywhere on the internet,what is normal operation fuel pressure for a flex fuel 5.3 liter? And can low fuel pressure cause random rough idle issues? Once you give it gas it run smoothly and has good power. No codes. Thanks for any help.

  30. Avataaar/Circle Created with python_avatars Derek Garcia says:

    Thank you. I have a 99 gmc Sierra 5.3liter vortex that misses when it's cold and once it warms up its fine. I believe it's a intake vacuum leak too.

  31. Avataaar/Circle Created with python_avatars Donnie Robertson says:

    Great job

  32. Avataaar/Circle Created with python_avatars Donnie Robertson says:

    Second time watching 7/8/2020

  33. Avataaar/Circle Created with python_avatars William Patterson says:

    Any videos on a 2005 chevy 6.0 vortec that idles slow when warmed up…no codes

  34. Avataaar/Circle Created with python_avatars Bananas Explains says:

    when my engine had vacuum leaks the RPM always shot up to 2000 rpm or more when idling (toyota 7K engine)

  35. Avataaar/Circle Created with python_avatars D Zimzy says:

    What about lean code and misfire codes on bank 2 when warm/hot at idle? Changed all plugs and wires, had one code once for misfire #4 cylinder so changed the coil for that as well. Plugs from bank one looked nice and golden colour all bank 2 plugs were black???

  36. Avataaar/Circle Created with python_avatars Walter Schroeder says:

    My 5.3 avalache is doing the same thing except I live in northern canada and when it below about minus 12 degrees centigrade it runs rough at start up the when I go about 5 miles and engine temp comes up to almost normal it start bucking and kicking and instant fuel economy goes to 5 miles per gallon. If outside warms up to minus 10 or more it doesn't do it but fuel economy is only 15 miles per gallon. I changed the spark plugs and the drivers side bank were normal tan color but passenger side bank were black. On a really warm day plus 10 it runs quite good after about 5 miles and fuel economy goes to 17-18 mpg. I've had random miss fire codes. One option is to wait for summer. I was thinking intake leak as well and after watching your video I'm convinvced

  37. Avataaar/Circle Created with python_avatars Cliff Beutler says:

    High idle cold start new iac 1997 Buick LeSabre 3.8 please help thinking vacuum leak leaking vacuum around plastic intake

  38. Avataaar/Circle Created with python_avatars James Baird says:

    I’m working on a 2016 Chevy 2500 6.0 gas 4×4 high country I rebuilt the front diff and was driving went to limp mode sounded like a intake manifold leak so I replaced the gasket the valley gasket injector o rings fuel rail side and manifold side throttle body gasket and now it’s still roaring what could it be

  39. Avataaar/Circle Created with python_avatars Puticio Saldana says:

    Thanks for sharing your knowledge. My 2001 f150 4.6 has the same symptoms. Followed your instrutions and found the leak at intake manifold gaskets. Out of curiosity i hooked up a homemade smoke machine to intake to see if there where any other leaks. Smoke verified the intake manifold gasket leak. But is it normal to see a little smoke out iac valve and egr valve?

  40. Avataaar/Circle Created with python_avatars hammer down says:

    wow same weather here same dam chevy issue.

  41. Avataaar/Circle Created with python_avatars Ruben Garcia says:

    Mag looks very high?

  42. Avataaar/Circle Created with python_avatars JSN GRMJO says:

    Hey thanks for your videos so helpful…I have a 1990 Toyota pick up 3vze engine and the problem I'm having is when the truck is cold if I attempt to drive it it runs but it feels like it had a fuel cut when you accelerate it acts like the accelerator does respond and it doesn't want too when you step on the gas when its reaching O/T problem go away …by the way fuel pump is new

  43. Avataaar/Circle Created with python_avatars Benjamin Bugarin says:

    Hi good very good video. How would I check my 94 454 tbi. It's in an 2500 2wd suburban Silverado trim.

    Not sure if all that matters.

    Huge rough high idle at cold start up.
    I've sprayed it left right. Around tbi. After warm up and cold. I couldn't tell any difference.

    Has new gasket on tbi. All of them a rebuild kit fixed a injectors house leak. And replace everything at once. But now

    It's doing it again.
    Rougher though…shuts off almost immediately after cold start like it's being drug down .

    Had most original parts on it still. Say all GM. And very Very fragile. Plastics keep breaking if I check connection. Omg.

    So I have replaced pig tails and on some with new tps iac map and Temp sensors. All temp sensors (3). No vacuum leaks I can see. Hoses are most new from previous vacuum leaks.

    Engine temp runs about 200 ,190

    Spray pattern looks good on inectors.
    After I Keep it running and drive it by tapping throttle to get going or will turn off. (Stall). It seems to run smoothly. And last shift about 45mph -50 mph feels stumbly. …if that's a word sloppy last shift. But runs strong so confused.

    At times when I do get it running and drive,….when I accelerate from a stop ( not stalling) will bogg down a smidge and take off .

    Has rebuild early 2000's 4l80e. From AAMCO out of their warranty. 4 years ago.
    First trans broken house and no reverse , high 2nd then shifted after 3000rpm .
    Has new distributor. Was going to rebuild old. But almost same price either way…
    New acdelc wires and plugs. .
    Timing@ 4degree btdc
    Timed with connection disconnected. Ran great. Then this very confusing issue

  44. Avataaar/Circle Created with python_avatars Doug says:

    Where's the follow up video. I would like to see the rnr, the bad gasket, and the estimate process (time parts etc). I thoght I could i try retorq the intake maybe add a couple ft/lbs before try do the whole thing myself. If its not to expensive i could have a shop do it. I was hoping that actually seing the job done would help me determine if its something my current disabilities would not allow me to complete.



  45. Avataaar/Circle Created with python_avatars Pedro Solis says:

    I have a 2004 Jeep Grand Cherokee 4.0 inline 6 and it’s stalling really bad like if it wants to turn off but only when I first start it up (cold start) after a few about 3 minutes of running it everything goes back to normal again any help please ?

  46. Avataaar/Circle Created with python_avatars 1SmOkEYj3 says:

    I have that same issue with the cold start rough idle than smooth out I took it to a couple shops and everybody wants to remove the heads but I don’t think that’s the issue but after seeing this it makes more sense

  47. Avataaar/Circle Created with python_avatars Prez408 says:

    Man i been going nuts over this problem my 03 avalanche was getting a p0300 code random misfires so i change all my spark plugs and wires ran good last night now this morning i went to turn it on and nope rough idle again once it warmed up it went back to normal so im just gonna do the gasket swap and see what happen thanks for the video

  48. Avataaar/Circle Created with python_avatars Mike Honcho says:

    5.3 vortec

  49. Avataaar/Circle Created with python_avatars Brad Fisher says:

    It would be nice , when you call the problem , that you could quote what it will cost the customer for that job.

  50. Avataaar/Circle Created with python_avatars Steve Berra says:

    When did they make a 5.7 in that year? Is it a stroker?

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