Chevy MYSTERY Misfire - Part1 ('98 K2500 Labor Day Special)

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  • เผยแพร่เมื่อ 24 ธ.ค. 2024

ความคิดเห็น • 291

  • @docfeelgood111
    @docfeelgood111 3 ปีที่แล้ว +29

    The reason it smoothed out under load is because a vacuum leak doesn't have as much of an effect then because you're adding fuel to compensate for unmetered air coming in through the intake leak. Then the air fuel ratio more closely matches what it should be. Great video I'm glad to see technicians doing a proper diagnosis instead of throwing parts at it.

    • @iamblaineful
      @iamblaineful 3 ปีที่แล้ว

      Most of the vacuum is made at idle, not at higher RPMs. The MAF was also reading way off at idle, 9.6g/s should be closer to 6.8g/s, so that left valve cover vent tube into the intake before the throttle body was clearly distorting it at well. The MAF is before the vacuum tub.

    • @mentaldemise
      @mentaldemise 3 ปีที่แล้ว

      Vacuum drops to near 0 at WOT doesn't it? That's what "vacuum reserves" are for(as I understand it)

    • @colejensen5812
      @colejensen5812 3 ปีที่แล้ว +1

      That is not completely accurate. Manifold pressure increases to near atmospheric pressure as you open the throttle blade. The pressure differential between atmosphere and the intake manifold is less thus air does not travel through
      the leak point under load.

  • @AP9311
    @AP9311 3 ปีที่แล้ว +12

    Lol Ivan, sounds all to common problem!! Had that exact same issue with my suburban! I bought mahle intake gaskets instead of felpro as they're more solid built. I had pcv issues with high idle. I indeed replaced the pcv with oem. Did not fix it, found out that i was getting to much vacuum in the crankcase, the gaskets were bad, as the water jackets clogging up. Did full flush, fresh gaskets really cleaned the surfaces, never had a problem since. 260,000 and still going! They're really well built, solid motor if well taken care of.

  • @WatchWesWork
    @WatchWesWork 3 ปีที่แล้ว +32

    Interesting failure mode! Normally they just leak coolant everywhere...

    • @PineHollowAutoDiagnostics
      @PineHollowAutoDiagnostics  3 ปีที่แล้ว +5

      Lol! Yeah very weird 😅

    • @111-c7x2t
      @111-c7x2t 3 ปีที่แล้ว +1

      Hi Wes Great to see you here, how long you've been watchin russian repair videos?

    • @mjmcomputers
      @mjmcomputers 3 ปีที่แล้ว +2

      Yep these are notorious for sending coolant into the engine. I’ve heard a lot of 5.0 and 5.7 vortecs knocking from the coolant oil sludge taking the bearings out.

    • @wildman1137
      @wildman1137 3 ปีที่แล้ว +2

      @@mjmcomputers
      That's called a lack of maintenance. In other words, neglect. Not a vehicle fault.

    • @mjmcomputers
      @mjmcomputers 3 ปีที่แล้ว

      @@wildman1137 bad design on the original intake gaskets on these. They normally fail at under 100k.

  • @claytoncoolidge992
    @claytoncoolidge992 3 ปีที่แล้ว +16

    As soon as you said misfire with no code and high idle code I just shook my head and reached behind the seat of my 95 burban and grabbed the intake gasket set. Its a common issue that many people don't really realize. It usually doesn't manifest with many symptoms on these except a slightly high idle witch most don't really notice a shake at low rpm but when u hammer it everything is perfect and you can see the misfire disappear. It can be frustrating especially if everything is checked out ok and you find a worn out pcv valve or bad vacuum lines and assume that you nailed it. If this engine doesn't use the plastic and rubber o ring style intake gaskets (idr witch year they started using that style but 98 is close to the change) as much as some will reeee about it best long-term solution that I've had great longevity from is to coat both sides of the entire gasket surface with rtv and flush out the dexcool and put green back in it. I do the rtv on the gaskets cause the dexcool causes pitting and I have found that using rtv just around the coolant ports does prevent coolant leaks but it causes the gaskets to blow easier and cause more vacuum leaks. I currently have 3 years and most of 100k miles on the last set I installed. Generally speaking on most any SBC 5 years seems to be the time frame that the intake gaskets seem to start leaking coolant or vacuum or both. The gaskets get hard and brittle and then if you get nice and warm while working it hard by towing heavy wagons or anything like that. Doesn't take much to get a leak at that point. We have had the 88-98 chevy trucks as our farm trucks for 20+ years and it is almost clock work to have to do the intake gaskets on them at 3-5 years always ends up being july-early September during the dog days and ironically right during the heavy hay and haylage season so hauling wagons and getting them nice and warm under heavy load and as soon as I get a break in the fall I swap a new set in before the winter weather sets in.

    • @PineHollowAutoDiagnostics
      @PineHollowAutoDiagnostics  3 ปีที่แล้ว +7

      Sounds like you have a lot of experience with these trucks Clayton! Which brand of gasket do you prefer?

    • @claytoncoolidge992
      @claytoncoolidge992 3 ปีที่แล้ว +8

      @@PineHollowAutoDiagnostics felpro. They tend to be what is most commonly stocked. I don't really see much difference between the different brands. Only so much that can be different and if your gonna apply rtv I've honestly cut a cereal box and made a set of gaskets a few times in a pinch on on the side of the road after blowing the coolant port and leaking fast. If you've done it a few times can be changed out in about an hour (atleast I could prior to having 3 discs removed from my lower back now its closer to 2 hours).

    • @Garth2011
      @Garth2011 3 ปีที่แล้ว +2

      @@claytoncoolidge992 I believe Felpro and Victor are the best choice. they both tend to exceed GM in upgrades and quality most.

    • @jeffreywilsonrubikscubeonb2428
      @jeffreywilsonrubikscubeonb2428 3 ปีที่แล้ว +3

      @@claytoncoolidge992I was a gm dealer tech for years and I agree. Doesn't matter much which gasket is used if you use rtv to compensate for the pitting. Being in the aftermarket world now for over a decade I find rtv to be the savior on many issues. Early 2000s Toyota's with common timing chain tensioner leaks at right rear of engine bay is a great example. This leaks oil all over power steering pump which commonly gets misdiagnosed as the issue. It's an o ring that fails on tensioner...and even if you replace the tensioner assembly (comes with new o ring) or just the o ring... This will always fail again within 500 to 10 thousand km in my experience. Adding rtv to the o ring has eliminated all comebacks. I like to follow service manual as much as I can until i get tired of comebacks lol. There is one manufacturer out there that I won't mention that if it has a transmission oil pan leak..i get rid of gasket and don't order another...just clean surfaces well and use red Rtv... hasn't let me down since. I've seen the thin cardboard trick with rtv before when I lived in Asia for a while. Works good. Even saw leaking I ejector o rings on heavy equipment fixed with thread ripped off the operators shirt... 😎

    • @claytoncoolidge992
      @claytoncoolidge992 3 ปีที่แล้ว +3

      @@jeffreywilsonrubikscubeonb2428 lol ikr I'm pretty sure I know exactly the trans pans you are referring to 😁 i totally agree though if I can do a job once for someone and not have to worry about a come back simply because I can supplement the oem and improve upon the improved redesign then im all for it. Been many times that a couple of extra seconds to toss a little rtv on a gasket made all the difference. The best one I've ever pulled off was on a 1953 john deere 60 head gasket I was 16 or 17 so I can't claim that it was skill or knowledge but it was pure genius. Head was perfect except for a very very small chip that was too deep to machine out and the tractor not only had sentimental value to the customer but it was also all completely numbers matching original tractor. After several failures with multiple shops including the dealer I offered to look at it and see if I could find a way to get it to work and seal and stay sealed. I replaced all the head studs and then used one used gasket and one new one and put red rtv in between the 2 gaskets and on both sides of the outer faces and put it together completely disregarded the torque specs and put a 3/4 drive breaker bar with a 5 foot cheater pipe on the end of it and slowly working in the proper pattern but making sure that I started and ended each pass on the stud closest to the bad spot on the head cranked them as tight as I could possibly get them. And then let it set empty for several days. I never filled the coolant till I got the tractor running and warmed up a couple of times dry. When I filled the coolant up there wasn't any sign of leaking till it built up to full pressure in the system and was very very small. So pulled the valve cover and had the customer help me to tighten the bolts while engine was hot and we cranked another half to 3/4 turn out of them. 21 years and its never blown again it will leak a tiny bit if you are working it too hard at full throttle on a hot day but once u see it leaking as long as u back off the throttle a bit it stops leaking and is all fine. Its never leaked coolant into the cylinder since I did them witch was the major problem.. a small occasional external leak is not a problem considering

  • @scotttucker4075
    @scotttucker4075 3 ปีที่แล้ว +7

    That's a a good diagnostic boy ,,, truck is probably older than he is,, we had a lot of trouble with those intake gaskets leaking on those engines normally coolant haven't seen one with vacuum that's a good catch,, great job

  • @marklaw3654
    @marklaw3654 หลายเดือนก่อน +1

    I had so many issues and codes on my 96 1500 chevy truck. Check engine light would not go away.
    After a year of sitting, I finally decided to change the spider injector, took me a couple of days, I took my time.
    I was nervous to start it when I was done. It started right up, no check engine light.
    It passed emissions.
    Super happy.

    • @laramona3165
      @laramona3165 20 วันที่ผ่านมา

      I just replaced the injector spider on my 97 silverado 5.7 vortec and it's all shaking and doesn't accelerate just shuts down. Any advice?

  • @ecaparts
    @ecaparts 3 ปีที่แล้ว +16

    Ahhh, you heard me screaming at my phone. Intake gaskets!! Misfire worst at idle (high vacuum - throttle plate closed) the excess air creates an extremely lean condition in cylinder #5 with little to no contribution. However with a MAF vehicle, I would expect lean codes on both banks. But considering the age of this thing it doesn’t surprise me, doesn’t even set misfire codes! Also good find with the PCV valve. Can’t wait to see the Russian repair in part 2…

    • @TractorWrangler01
      @TractorWrangler01 3 ปีที่แล้ว

      Haha! Me to! We must have been making a hell of a racket.

    • @iamblaineful
      @iamblaineful 3 ปีที่แล้ว +1

      MAF was reading 9.6 to 10.1 at idle, way too high. If the computer was following it, to maintain stoichiometric, it would be adding fuel. It should be 6.3 to 6.8g/s on that rig. Remember, it's got the old skool O2 sensors... That valve cover tube goes into the intake between the MAF and the throttle body likely tricking it by pulling more air into the crankcase at idle than would normally get by the idle circuit, causing the higher reading in MAF.

    • @RG-cd3uf
      @RG-cd3uf ปีที่แล้ว +1

      Faulty fuel pressure regulator will bleed into cylinder 5 on these spider injection sbc engines and cause this #5 misfire. By the look of that plug.. I'd say it's possible

    • @jamesm568
      @jamesm568 ปีที่แล้ว

      ​@@RG-cd3uf or cause an intake backfire and blowout the upper intake seal or crack the upper intake manifold.

  • @metoon3092
    @metoon3092 3 ปีที่แล้ว +13

    Very cool diagnostics ! Old Chey's never die, they just get a bit of Russian help on occasion ! Listen closely to the audio in this video. Shhhh, listen,... You can hear Bob Seger singing......

  • @mjmcomputers
    @mjmcomputers 3 ปีที่แล้ว +13

    The Intake gaskets are notorious for going bad on those. There are premium updated gaskets that hold up better. Make sure the manifold isn’t warped as well.

    • @williamwhite9767
      @williamwhite9767 3 ปีที่แล้ว +3

      I never had an issue with intake gaskets. I think the problem arises when the mechanic isn't careful enough setting the intake and displaces a gasket. I used shellac to hold them in place and put a dab of sealant on the joints and very carefully set the intake down.

    • @MagicMike007
      @MagicMike007 ปีที่แล้ว

      I’ve had five of these trucks and every one of them had to have the intake gaskets replaced between 100-120k miles. Piss poor gaskets. The new upgraded gaskets was the fix.

  • @somerandomguy3868
    @somerandomguy3868 3 ปีที่แล้ว +4

    Thought for sure you nailed it with the injector test, my immediate thought was head gasket slight coolent intrusion into 5

    • @Garth2011
      @Garth2011 3 ปีที่แล้ว +1

      Can you bend a rod starting the engine after injecting fuel into the cylinders with the engine off??

    • @PineHollowAutoDiagnostics
      @PineHollowAutoDiagnostics  3 ปีที่แล้ว

      @@Garth2011 If you dump enough fuel in, yes.

  • @imnotdon3765
    @imnotdon3765 3 ปีที่แล้ว +10

    Would Eric have sprayed brake clean in the general area of the suspected leak to see if the idle would change?

    • @Chris-kq7ko
      @Chris-kq7ko 3 ปีที่แล้ว +1

      he would probably pull out the Avoca Smoka

    • @williamwhite9767
      @williamwhite9767 3 ปีที่แล้ว +4

      It's leaking underneath the inake manifold. A smoker wouldn't tell you anything. Well, maybe when it came out the PCV valve cover hole.

    • @PineHollowAutoDiagnostics
      @PineHollowAutoDiagnostics  3 ปีที่แล้ว +7

      Where would you spray the brake clean? No external vacuum leaks...

    • @imnotdon3765
      @imnotdon3765 3 ปีที่แล้ว

      @@PineHollowAutoDiagnostics ahhh. Did t know that!

  • @Mr2004MCSS
    @Mr2004MCSS 3 ปีที่แล้ว +1

    Great video. I've owned a 98 K1500 with this engine since new and I'm on my third intake manifold gasket with the last one being replaced at around 75-80,000 miles. There have been three revisions of the intake gasket over the years and my truck has version two. I'm at around 142,000 miles now and so far the intake gasket is still good.
    Years ago I had a high idle situation with this truck and it ended up being the thermostat was stuck open so the truck never warmed up to the correct operating temp and had the idle at high all of the time. New thermostat and idle returned to normal.
    The AC compressors on these trucks are a know issue for leaking and that one is definitely leaking so the owner will be looking at a compressor replacement in the near future. There are one piece case clones out there that are way better than the HT6 that these trucks use. I've been using a Seltec-Valeo compressor on my truck for years and it's still leak free. I also own a 98 K3500 with the 7.4L big block and have replaced it's compressor with a clone as well with no leaking problems.

  • @rrmech11
    @rrmech11 3 ปีที่แล้ว +4

    Sweet Diag. Ivan. Love when you do are great country holiday specials. Hope you and your family have a wonderful labor day. Say hello to your brother in my home state in Indiana for me. My friend and I just got the 1986 kawasaki 900 Eliminator running. Had a coolant leak. All is well now. 👍👍

  • @dans_Learning_Curve
    @dans_Learning_Curve 3 ปีที่แล้ว +10

    Great find!
    The customer reported no AC. That's one thing they know that isn't working because they're *HOT!*
    I have a feeling that the clutch gap is getting too wide and the clutch isn't closing all of the time. Saw this on my '03 Forester.
    Try removing a shim on the clutch to close the gap. The other solution would be to replace the clutch or compressor.

    • @GhettoWagon
      @GhettoWagon 3 ปีที่แล้ว +3

      Cant remove a shim no shims on these you just get the GM compressor hub/ clutch tool and push the clutch fitment a little tighter. These compressors are not good. Alot of case leaks. Now all the replacements are china. Every one. even GM. They have some nasty looking compressor on it and a high side cap that looks busted off in the valve

    • @dans_Learning_Curve
      @dans_Learning_Curve 3 ปีที่แล้ว

      @@GhettoWagon thanks for the information!

  • @SonOfNone
    @SonOfNone 10 หลายเดือนก่อน

    I've been fighting an issue in my '98 Yykon (5.7 vortec) for a couole months. When I bought it, I performed a full tuneup [iridium Spark plugs, wires, cap and rotor- all acdelco, air filter, oil change using Mobil1 high mileage full synthetic, K&N Gold high-flow oil filter]. Started out as hesitation at low idle, then progressed to hesitating and nearly dying unless the engine was cold, then progressed to the same but would even out if the RPM was above 2,000.
    I replaced bank 1 and 2 o2 sensors, no luck. Less than 3k miles after oil change, it was black and smelled of gas. I got to the point of thinking a valve was getting stuck, so I used Lucas full synthetic high mileage oil treatment, ran the engine above 2,000 RPM for several minutes, then noticed the problem was 90% solved- it runs much better, but not entirely perfect. So I presume my diagnosis is correct, and now I gotta dive in to the valve cover and inspect rocker arms and valves. Wish me luck.

  • @akhtarkh
    @akhtarkh 3 ปีที่แล้ว +11

    A little schematic diagram showing PCV valve, idle air valve etc would help in understanding the issue. Thanks as always

  • @TractorWrangler01
    @TractorWrangler01 3 ปีที่แล้ว

    You're 100% correct. Nice diagnosis. He will get better mileage and more power after you fix that.

  • @roxanneabbott8424
    @roxanneabbott8424 3 ปีที่แล้ว +2

    Looking for part 2 to come!! Great diag Ivan!

  • @inothome
    @inothome 3 ปีที่แล้ว +18

    As soon as I saw the high idle and zero IAC it was a vacuum leak. Good to see you didn't go down the low compression rabbit hole. Easy to overthink things sometimes, but back to the basics and it's just a vacuum leak. Hopefully just the gasket like you said and not some cracked intake runner that never happens...... But would make for a good video!

  • @bobbydelamar606
    @bobbydelamar606 3 ปีที่แล้ว +3

    I just fixed an Expedition with very low idle. So low it was dying. Only codes are P0420, P0430 and P0705. Ended up being just a dirty throttle body.

    • @PineHollowAutoDiagnostics
      @PineHollowAutoDiagnostics  3 ปีที่แล้ว +1

      NO PARTS REQUIRED :))

    • @bobbydelamar606
      @bobbydelamar606 3 ปีที่แล้ว +1

      @@PineHollowAutoDiagnostics Heck yeah! And thanks to you I'm interested in actually diagnosing. Instead of guessing and fire the parts cannon.

  • @billziegmond4943
    @billziegmond4943 3 ปีที่แล้ว +2

    As soon as I found that much vacuum out would come the Avoca Smoka! LOL

  • @almartin9327
    @almartin9327 7 หลายเดือนก่อน

    Good video....he walks you through his diagnosis and at the same time

  • @classicwefi
    @classicwefi 3 ปีที่แล้ว +5

    I like to use the felpro rubber backed steel intake gaskets on those way better than the flimsy plastic original type.

  • @kdmq
    @kdmq 3 ปีที่แล้ว +18

    I think the intake manifold gasket makes sense cause cyl 7 was misfiring a bit as well as 5 and they are neighbouring cylinders. I am surprised you never mentioned cyl 7 misfiring. I am excited for part 2 cause I am wondering if the intake gasket is literally just another red herring lol, but the crankcase was under abnormally high vacuum for sure.

  • @baxrok2.
    @baxrok2. 3 ปีที่แล้ว +2

    A gross leak indeed. Thanks Ivan!

  • @leroyconley5647
    @leroyconley5647 3 ปีที่แล้ว +4

    This engine is known for intake manifold gaskets going bad at 100,000 miles. This is a strong possibility . I have 3000.00 miles on mine and have had to replace this gasket twice

  • @Discretesignals
    @Discretesignals 3 ปีที่แล้ว +2

    Don't ever run the spark plug outside the cylinder like that unless you want to start an engine bay fire!

  • @agmc4me
    @agmc4me 3 ปีที่แล้ว +1

    Enjoy your labor day weekend. Can't wait for part 2

  • @randymarion2466
    @randymarion2466 3 ปีที่แล้ว +2

    With a vacuum leak, shouldn't the fuel trims be out of whack?

    • @PineHollowAutoDiagnostics
      @PineHollowAutoDiagnostics  3 ปีที่แล้ว

      Great question! Can you explain why they were NOT out of whack in this particular case?

    • @randymarion2466
      @randymarion2466 3 ปีที่แล้ว

      @@PineHollowAutoDiagnostics I have been thinking about that .... fuel trims get out of whack when unmetered air gets into the system somehow. In this case, it seems the intake manifold gasket has a leak into the crankcase creating abnormally high vacuum at idle. The MAP sensor monitors what is going on in the manifold... possibly it is compensating for the leak?

    • @PineHollowAutoDiagnostics
      @PineHollowAutoDiagnostics  3 ปีที่แล้ว

      @@randymarion2466 You're on the right track with the "unmetered air" theory. In this case is the extra air being sucked through the crankcase vent hose metered by the MAF?

  • @cameltube-vk7el
    @cameltube-vk7el ปีที่แล้ว

    nice job. . . . . . . . .I am about to venture through some similar issues, I thank you for sharing bro!!!
    Part two I am in !

  • @ThatEEguy2818
    @ThatEEguy2818 3 ปีที่แล้ว +1

    Why would an intake manifold gasket cause this? Is the mounting surface on the head open to the crankcase? If so, why?

  • @yomomma9070
    @yomomma9070 3 ปีที่แล้ว +2

    Ivan, the HR6 compressor on this engine is notorious for leaking freon. And from the looks of this one it is too. Someone may have recently recharged it.

  • @johnclamshellsp1969
    @johnclamshellsp1969 3 ปีที่แล้ว +2

    Great video. Had the same issue years ago on my 99 Tahoe. Please install the Vortec marine version intake gasket, made of Stainless steel and rubber seals.

    • @PineHollowAutoDiagnostics
      @PineHollowAutoDiagnostics  3 ปีที่แล้ว +1

      That's a great idea!

    • @johnclamshellsp1969
      @johnclamshellsp1969 3 ปีที่แล้ว +2

      @@PineHollowAutoDiagnostics For the 1996 and later 5.7 Vortec/Mercruiser (all the same). Should be Felpro FEL-PRO MS 98000 intake set. Also, a must replace, Fel-Pro ES72224 Intake Manifold Bolt Set, they will be corroded to death. Another fail on rare occasions is the upper plenum, clean and look for cracks. If the vacuum leak issue is not fixed soon, the engine will become an internal water pump and suck all coolant into the block/pan areas. The engine will quickly overheat and crack the heads. I know this well, it happened to me.
      Take care
      John A 60107

  • @arsinoeivlostprincess4228
    @arsinoeivlostprincess4228 3 ปีที่แล้ว +2

    Excellent! looking forward to pt 2. I caught the vac leak early on only because I watch all yours and fifteen or twenty others others every week for the last five or ten years. But I have little practical exp. Love this stuff but I'm glad I don't have to be doing it. Not a lot of stuff in the bay in the way...Should be interesting. With all the leaking the A/F ratio didn't change that much I guess it could compensate. See what you find.

  • @circa366
    @circa366 6 หลายเดือนก่อน

    Thanks for a solid diag video. Im no expert but I feel like Im on track now to find the right solution to my issue! Thanks!

  • @Garth2011
    @Garth2011 3 ปีที่แล้ว +1

    I would add onto the parts list, 8 plugs, a set of ignition wires and a PCV valve for good measure as they are all very old looking and the labor cost would mostly be included with the intake manifold gaskets or be greatly reduced. Spark plugs are cheap enough I wouldn't try to clean them and unless those ignition wires were replaced within 5 years or so, I'd replace them too. I believe the only internal concerns on those 5.7L are the exhaust valve stem seals tend to wear out by 76,000 to 100,000 miles.

  • @jefferywarburton2116
    @jefferywarburton2116 3 ปีที่แล้ว +2

    It would be good to test the egr v. before taking off the intake but its prob. fine its not running that bad

    • @ludvigericson6930
      @ludvigericson6930 3 ปีที่แล้ว

      Stuck EGR should not cause crankcase vacuum surely? Just terrible performance.

    • @jefferywarburton2116
      @jefferywarburton2116 3 ปีที่แล้ว

      @@ludvigericson6930 Right thats why you test it while your there. buying intake gaskets.

  • @jeffreyh1297
    @jeffreyh1297 ปีที่แล้ว

    Man Thanks for making this video you gave me a lot of pointers I been trying to find out why my 97 chevy had a misfire still at cylinder 8, I already replaced injectors and spark plugs this video really helped

  • @JSchrumm
    @JSchrumm 3 ปีที่แล้ว +2

    Magical truck runs on no fuel, I want one.

  • @JamesSmith-xs7sr
    @JamesSmith-xs7sr 5 หลายเดือนก่อน

    JUST went through this, 97 sierra 5.7. #5 misfire... (misfire constant, brought in from another shop, after they replaced all tune up parts.) # 5 spark plug bone dry, no fuel smell. Compression 165 psi. ALL injectors dropped 13 lbs during the drop test. Verify 3/4" air gap spark test. Run engine, fuel trim high bank 1 at idle. (Plus 20%) Fuel pressure stays around 54 psi, no drop after shut down. Owner replaced injector assy 2 years ago from Amazon. Noticed coolant reservoir low, topped off, pressurized, held stable for 1 hour. No signs of fuel in the plenum
    Remove intake, #5 & #7 injectors reversed! Owner said it ran good for awhile after replacement, wtf? Verify spray when activated, re installed proper. Run engine, still misfired UNTILL eng warm. Signs of coolant leakage rear of b/1 head. Replaced intake manifold gasket, NO misfiring, fuel trim under 10. I wasted a lotta time on this diag. Gotta think!

  • @lylecheckeye6300
    @lylecheckeye6300 3 ปีที่แล้ว

    Wonder if a smoke test would pinpoint the issue better ?? or the scanner danner method of water bottle with a tiny hole and spray around the area and listen for leak ? Great show

  • @BustedtoBuilt
    @BustedtoBuilt 3 ปีที่แล้ว +3

    Nice work! Love watching your videos. Keep it up!

  • @kerryb2689
    @kerryb2689 3 ปีที่แล้ว

    I recently had an intermittent misfire at idle #6...was worst no load @1400 rpm, fine under load. Opened hood while running & #6 spark plug was shaking (it was loose). Tightened plug and now it's ok. Hard to believe that small of a vacuum leak caused a misfire, but it was close to the spark.

  • @ws2664
    @ws2664 3 ปีที่แล้ว

    good job Ivan, even though parts will be required, your going to have to bite the bullitt and put them in

  • @farmermiyagi1338
    @farmermiyagi1338 3 ปีที่แล้ว +2

    I always, ALWAYS check for intake problems on these engines. Vacuum in the crankcase is a dead giveaway.

  • @wcmwfab935
    @wcmwfab935 2 ปีที่แล้ว

    So there should be no vacuum in the crank case, with the pcv valve blocked? I have vacuum in the crank case when I rev it. No vacuum leak at idle.

  • @alexg9155
    @alexg9155 3 ปีที่แล้ว +3

    3) Vacuum leak? That's why it smooths under load. 12 minutes in, let's see 😁
    At 18 minutes, vacuum is still there with PCV blocked off due to a leaky valve cover gasket maybe? Bank with affected cylinder (as there were also a few misses on number 7).
    EDIT: Aah crap, the intake manifold gasket :) Didn't think about the most obvious thing, lol.

    • @joebriano6090
      @joebriano6090 3 ปีที่แล้ว +1

      No lean code ? What were the fuel trim numbers?

    • @alexg9155
      @alexg9155 3 ปีที่แล้ว +2

      @@joebriano6090 It didn't set a misfire code either, who knows what kind of strategy the ecu has.

  • @kthwkr
    @kthwkr 3 ปีที่แล้ว +2

    Notice that the gas gauge is sitting on negative empty. Two times in my life I have run a car out of gas only to have the engine get fouled when I put in more gas. Never let a car get that empty. Assume the gas tank is contaminated with gas loving spiders.

    • @Garth2011
      @Garth2011 3 ปีที่แล้ว

      Not good for electric tank pumps, they overheat without fuel covering them

    • @PineHollowAutoDiagnostics
      @PineHollowAutoDiagnostics  3 ปีที่แล้ว

      Just an intermittent sending unit lol...it's a GM thing!

  • @davidwaskiewicz3289
    @davidwaskiewicz3289 3 ปีที่แล้ว

    Yup, intake leaking under manifold, fixed a few myself. Same symptoms,took a few to figure out😁

  • @lovetolearn5253
    @lovetolearn5253 3 ปีที่แล้ว

    You had me worried when I seen you giving up on the diag with the compression theory. I actually came across this before so I was thinking intake the whole time. Nice job.

  • @shanegoff217
    @shanegoff217 11 หลายเดือนก่อน

    I had a Silverado once that had fuel, spark, good compression but constant misfire on #2... had the converters checked...one of them on that bank was restricted

  • @kellyd887
    @kellyd887 3 ปีที่แล้ว

    What I need is a video on an OBD 1 88-95 GMC truck. Been trying to solve the mystery of a dead miss in open loop, that disappears as soon as the coolant temp reaches 40* C. Parts cannon has been fired, reloaded & fired again ! Lol Everything but the charcoal canister has been replaced and I do mean everything. I have no scanners or the knowledge to use them. Could be any thing from the wrong IAC counts to a sticking push rod. Been at this for 2 yrs now, sure wish I had you around for a day I'm sure you'd make short work of it. Love yer video's, love learning from you Bro, keep fighting the good fight my friend ! PS. I smoke tested it. If it is a vacuum leak its not the intake. 94 Yukon by the way

  • @jjscalifornia5086
    @jjscalifornia5086 3 ปีที่แล้ว

    Fuel Trim Question: As the #5 cylinder was sucking oil vapors from the crankcase, was the fuel trim negative, i.e. rich as a result of oil being drawn into the intake manifold? Normally, a vacuum leak causes a + positive fuel trim due to excess air drawn into the cylinders. However, in this case, the vacuum leak was not to the outside air, but rather to the internal crankcase fumes.

  • @JoelAutomotiveInaction
    @JoelAutomotiveInaction 3 ปีที่แล้ว

    I did the same test you did at 3:18 one time and the vehicle got on fire , bmw had to go the junk yard , my fire stinger was expired and I found no way to stop the flames .

  • @hehunches
    @hehunches 3 ปีที่แล้ว

    this video is ridiculously good looking

  • @danielholtzapple7124
    @danielholtzapple7124 2 ปีที่แล้ว

    That's the same thing my 95 gmc sierra 2500 5.7 did. Every 2 months I had to clean number 1 cylinder plug. It would completely fill the gap and the area around the electrode. I'd keep a new plug in glove box. Strangest thing was #1 would get fouled like that and #5 was white at tip. I don't care those gm 350s are monster tanks. Just got another one last month. Has a slight miss but that truck hauls weight and don't complain. The first 1 I bought I could pull 3 zero turns around up hills and all.

  • @mentaldemise
    @mentaldemise 3 ปีที่แล้ว +1

    Wouldn't the long term fuel trims also be way positive? I had a massive leak around the intake snorkel thing and my fuel trims went down 25% when I sealed it up with RTV.

  • @derrickodyes1934
    @derrickodyes1934 3 ปีที่แล้ว

    the misfire counters are there but relaxed on thes hd trucks over 8500 gvwr. If engine is sound almost always the spider even if they flow good

  • @lawsautomotive108
    @lawsautomotive108 ปีที่แล้ว

    Hey man, I was prompted to check this video out. You're pretty decent guy. You also know how to diagnose. Good video!

  • @frankjohn4302
    @frankjohn4302 3 ปีที่แล้ว

    Good job iac was compensating for vacuum leak

  • @ricktrent275
    @ricktrent275 9 หลายเดือนก่อน

    I got a 97, just thought i'd check it out for future ref. All's ok now.

  • @nodieusa
    @nodieusa 3 ปีที่แล้ว

    I believe my 99 Tahoe has the exact same issue and my mechanic just replaced the intake manifold gasket. Wonder if the gasket isn't seated properly. There goes more money (and labor)....

  • @satoruo2753
    @satoruo2753 3 ปีที่แล้ว

    Saw the thumbnail and instantly thought "vortec injector failure"!

  • @2packs4sure
    @2packs4sure 3 ปีที่แล้ว +1

    I would bet that that A/C does need a charge because that compressor is pretty dang oily.

  • @MrXyzasdf
    @MrXyzasdf 3 ปีที่แล้ว +4

    Ivan, when you had the #5 spark plug out, how much more difficult would it have been to run a quick compression test on that cylinder?

  • @kellismith4329
    @kellismith4329 2 ปีที่แล้ว

    I have had to replace that spider injector in mine before - is there some way you can access the individual injectors to energize without using a scan tol on these trucks ?

  • @artemovsk1
    @artemovsk1 3 ปีที่แล้ว

    Saw the RPM too high code and instantly thought of a vacuum leak in my mind haha

  • @wallyg4445
    @wallyg4445 3 ปีที่แล้ว +1

    There's your problem , lady!! Hmmmm, where have i heard that before??? Lol

  • @dyizhere
    @dyizhere 3 ปีที่แล้ว +1

    Nice diag! Spray the intake with carb cleaner or brake clean to confirm the intake leak?

  • @mikesecoski8429
    @mikesecoski8429 2 ปีที่แล้ว

    By any chance I have the same problem,no 5 ,always replacing that plug,did ya check the distributor cap ,they are known for cross fire

    • @mikesecoski8429
      @mikesecoski8429 2 ปีที่แล้ว

      The crab cap is notorious for this problem in design

  • @billsmith2212
    @billsmith2212 3 ปีที่แล้ว

    If that leak is unmetered air , wouldn't the fuel trim numbers be rich because the lean condition would call for more fuel to be added ?

  • @beetee801
    @beetee801 2 ปีที่แล้ว

    I got a 98 z71 5.7 engine rebuilt about 4000 mi ago has multiple cylinder misfires only when warm only in low rpms I replaced literally everything, no codes. Any ideas?

  • @rogermerritt6470
    @rogermerritt6470 2 ปีที่แล้ว

    Very interesting video. I've got a 1999 GMC K1500 Suburban with the 5.7L engine. I'm getting misfires while at stop light and idle is at 600. Also motor shakes sometimes between 1000-1900 RPM. Usually while in overdrive. Recently tried changing the spider injectors with ones made in china, but they here bad and got my money back. I've changed just about every sensor on this Suburban with no luck. Think I'll take the intake manafold off and see if gasket is in place properly.

    • @jonschwartz9669
      @jonschwartz9669 2 ปีที่แล้ว

      Does your check engine light come on with this misfire?

    • @rogermerritt6470
      @rogermerritt6470 2 ปีที่แล้ว

      @@jonschwartz9669 No check engine light. I have a code reader and there are no codes stored. When I come to a stop it takes about 5 seconds before symtom shows up. Suspecting a bad fuel injector.

    • @jonschwartz9669
      @jonschwartz9669 2 ปีที่แล้ว

      @@rogermerritt6470 Try a bottle of recline fuel treatment it has the highest concentration of PEA this is the best carbon cleaning product on the market also a manifold gasket that leaks can cause misfire a weak fuel pump a dirty fuel filter a weak fuel pressure regulator under upper manifold plenum its either fire or fuel

    • @rogermerritt6470
      @rogermerritt6470 2 ปีที่แล้ว

      @@jonschwartz9669 I have replace the fuel pump, but not the fuel filter. The lines are just so rusty in that area. The engine runs just fine when it's cold. Computer module was swapped out with no change. Very strange problem.

  • @think2cre81
    @think2cre81 ปีที่แล้ว

    Great videos, sir . I have the same problem right now with my 1997 Silverado 1500 5.7 vortex engine. How much should it cost to replace those intake manifold gaskets? I already replaced the plugs and plug wires and caps and distributor cap and rotor. And checked for exterior vacuum leaks . So I'm down to this exact issue with my number 5 cylinder code . Please if you or anyone else reads this message. What it will cost to replace those intake gaskets. Thank you 😊

  • @bertvisser6423
    @bertvisser6423 3 ปีที่แล้ว

    96-99 notorious for defective intake gaskets,you will find the hard plastic broken around the silicone. They love leaking coolant into engine there too and wreck rod bearrings on #2

  • @kandkob
    @kandkob 3 ปีที่แล้ว +1

    I would have sprayed engine start around number 5 inlet manifold to check for a vacuum leak, quickest way!

    • @PineHollowAutoDiagnostics
      @PineHollowAutoDiagnostics  3 ปีที่แล้ว

      Except the leak is on the bottom side to the crankcase so spraying from the outside would be a fruitless endeavor :)

    • @kandkob
      @kandkob 3 ปีที่แล้ว

      @@PineHollowAutoDiagnostics Good to know. Love your vidios!

  • @ScottHenion
    @ScottHenion 3 ปีที่แล้ว +1

    If I were doing an intake gasket, I'd also upgrade the spider injection to the improved one with real injectors. GM makes an upgrade kit that bolts right in. Better mileage and a bit more power. Not expensive compared to having to go in later and fix a popped off or cracked plastic injector tube.

    • @PineHollowAutoDiagnostics
      @PineHollowAutoDiagnostics  3 ปีที่แล้ว +4

      "If it ain't broke don't touch it " is my philosophy 😉

    • @noblesavage413
      @noblesavage413 3 ปีที่แล้ว

      @@PineHollowAutoDiagnostics If it ain't broke, keep fixing it til it is!

    • @scraiga66
      @scraiga66 3 ปีที่แล้ว

      Also makes engine less finicky about fuel pressure.

  • @JBlake-moon-shdo
    @JBlake-moon-shdo 3 ปีที่แล้ว

    Ivan
    Can you tell me why you didn't look at MAF. I'm not sure that's why I'm asking.

  • @beverlyroemer5161
    @beverlyroemer5161 3 ปีที่แล้ว

    I have a thought 💭 or maybe question 🙋🏼‍♀️ would the misfire not be throwing the code or detected because it doesn’t drive fast enough or long enough because it’s driven around as a farm truck 🛻 or does that not really matte?.?.?.

  • @Graham_Wideman
    @Graham_Wideman 3 ปีที่แล้ว

    OK, I'm confused! Where is the location that the intake manifold gasket is somehow (supposed to be) separating the manifold vacuum from the the crankcase air?

    • @inothome
      @inothome 3 ปีที่แล้ว +1

      Each intake runner has manifold vacuum to it and the intake itself covers the valley of the engine. So if the intake gasket leaks on the bottom side of a runner (s), between the intake and the head, it will pull a vacuum through the engine valley and can also pull in oil. Since there is oil splashing around in the valley. Make sense? If it leaks on the top, it will just leak in outside air and sometimes you can hear it whistle and if you spray carb cleaner on it the engine RPM will go up. In this case, is appears to be leaking on the underside so it's pulling in air from the engine valley.

    • @Graham_Wideman
      @Graham_Wideman 3 ปีที่แล้ว +1

      @@inothome Ah, I haven't disassembled a V8, and didn't appreciate that the top of the crankcase is open, and the intake manifold does double-duty as also a cover for the crankcase. Now it all makes sense. Thanks!

    • @inothome
      @inothome 3 ปีที่แล้ว +2

      @@Graham_Wideman Yes, not all V8's are like that now, but all the older one's and the one on the video the intake is the top cover. Glad that helped explain it.

    • @graymodeler
      @graymodeler 3 ปีที่แล้ว

      @@Graham_Wideman Yep, some of the first GM engines had separate valley covers. My 54 Buick nailhead was like that. The small block Chevy came along in 1955 and incorporated the distributor, water neck, valley cover, crankcase breather oil fill, and intake manifold into one casting.

  • @philliphoang4
    @philliphoang4 ปีที่แล้ว

    Hello there , I have my 1995 GMC Sierra, start right up but then stall and when you put into D or R the engine shut off right away, I have no idea, so if you know please tell me what’s next I have to do. I’m replaced the whole new distributor idle air control. Egr valve , map sensor but still no luck , thanks

    • @PineHollowAutoDiagnostics
      @PineHollowAutoDiagnostics  ปีที่แล้ว

      What if you give it some gas when you shift? Is it a really violent shift? Stuck torque converter?

    • @philliphoang4
      @philliphoang4 ปีที่แล้ว

      @@PineHollowAutoDiagnostics , the shift still fine , but it just lost power when I’m move into D or R , before that the truck run fine

  • @PeteyG708
    @PeteyG708 3 ปีที่แล้ว

    Could you have sprayed some Brake Clean around that area of the intake manifold gasket for proof of concept?

  • @nickloss
    @nickloss 3 ปีที่แล้ว

    sounds like a leaking intake gasket, the reason they don't set a code is they usually seal up after driving a short while and the miss goes away. My 5.3 has a slightly bad gasket and if I let it idle for.a while in the winter It will start detecting a miss, goes away when you drive it.

  • @mikechiodetti4482
    @mikechiodetti4482 3 ปีที่แล้ว +2

    Common problem on these older GM engines. Make sure to use GM gaskets. If I remember right, GM updated that gasket.

  • @Walczyk
    @Walczyk 3 ปีที่แล้ว

    wouldn't a leaking gasket just equalize pressure to atmosphere? like you're saying a big vaccum leak is causing high vacuum?

  • @geraldfields8802
    @geraldfields8802 3 ปีที่แล้ว

    Throttle plate shaft bushing worn?

  • @williamwhite9767
    @williamwhite9767 3 ปีที่แล้ว

    I had 3 GM Goodwrench 350 V8s installed in my 86SS Monte Carlo. They would burn oil after a few thousand miles, all 3 of them. Two were replaced under warranty. Now that I have had a few years to think about it, I'm sure using RTV for an intake gasket was the problem and it was sucking oil from the lifter valley into the cylinders. I removed/replaced chevy V8 intake manifolds many times using gaskets and I never had an issue using gaskets. Ford uses it on the diff covers. I used it once and it leaked. I hate RTV when used as a gasket.

  • @derrickodyes1934
    @derrickodyes1934 3 ปีที่แล้ว

    on intermittant ac usually hi pressure switch on those. They drop out causing ac to shut off

  • @moviemania1137
    @moviemania1137 3 ปีที่แล้ว +7

    "Mystery misfire"
    ETCG: I'll just flush the engine with this caustic chemical.
    Also ETCG: The Odyssey engine blew up! I have the worst luck. 😂

    • @PineHollowAutoDiagnostics
      @PineHollowAutoDiagnostics  3 ปีที่แล้ว +4

      He blew up the engine?? Did he diagnose the misfire? 🤔

    • @billziegmond4943
      @billziegmond4943 3 ปีที่แล้ว +5

      @@PineHollowAutoDiagnostics I watched that video. When he pulled the valve cover. He saw the engine was full of sludge. So he decided to do the engine flush. It was an Odyssey with the VCM system. When it shut down some cylinders. Those cylinders filled with oil and kaboom!

    • @lrdisco2005
      @lrdisco2005 3 ปีที่แล้ว +1

      @@billziegmond4943 Flushing engines was something us oldies use to do. Modern engines with modern oil not worth the risk as Eric found out.

    • @DavidScheiber
      @DavidScheiber 3 ปีที่แล้ว +2

      You guys didn't even watch all the videos, in the tear-down he discovered that the engine being locking up was caused by lack of oil. The oil pickup was clogged with sludge that he suspected was knocked loose by the oil flush additive. He then went on to say he does not recommend using oil flush additives. I think he even mentioned he does not like the stuff in the video of him using it but he said he would try it.

    • @moviemania1137
      @moviemania1137 3 ปีที่แล้ว

      @@lrdisco2005 Yep! 😂

  • @dogsplantscarsneatstuff176
    @dogsplantscarsneatstuff176 3 ปีที่แล้ว

    Ivan when you do the intake manifold could you show what kind of shape it is in: if it is pitted or worn. Thanks in advance. My intake manifold on my gm 3.8 had some pitting and deep scars at a couple of non cylinder openings. I wonder if it was due to the orange coolant since I use the green now. I usually changed it every 3 years even if the bottle says 5 years /150K.

  • @billdursa4724
    @billdursa4724 3 ปีที่แล้ว

    My initial thought was vacuum leak. I've had similar experience on a 4.3 Vortec.

  • @canadatransistor
    @canadatransistor 3 ปีที่แล้ว

    Well, i'm not tone deaf in 1 khz door chime frequency. This video saved me a trip to the audiologist... LOL

  • @crabcake43011
    @crabcake43011 3 ปีที่แล้ว

    Nice shout out to Eric O.!👍

  • @EATSLEEPFARM
    @EATSLEEPFARM 3 ปีที่แล้ว

    I’ve got a 1998 with a 5.7. It’s a crank no start. After about a sec or so of cranking it’ll make a loud “ping”. This is just continuous everytime you crank it. No codes and can turn the engine over by hand. Any idea where to look? I have spark but I’m wondering if I’m getting spark at the right time… I don’t think it’s fuel as I’ve tried to start it with some carb clean and it won’t do anything. Thanks

    • @PineHollowAutoDiagnostics
      @PineHollowAutoDiagnostics  3 ปีที่แล้ว

      Yeah reset the distributor timing to OEM spec and see if it starts

    • @EATSLEEPFARM
      @EATSLEEPFARM 3 ปีที่แล้ว

      @@PineHollowAutoDiagnostics awesome!! Thanks Ivan😎

  • @nct9466
    @nct9466 2 ปีที่แล้ว

    Question:
    Would short or long term fuel trims not try richen up some seeing 1 cyl lean?
    Wouldn’t the O2 sensor also not command a richer mixture?

  • @paulstandaert5709
    @paulstandaert5709 3 ปีที่แล้ว

    The first thing that came to mind were those plastic intake manifold gaskets. They will also tend to cause coolant loss and a rise in oil level.

  • @BurningSteel69
    @BurningSteel69 2 ปีที่แล้ว

    I had a random misfire code -- I replaced the old loose, leaking GROMMET for PCV for a tight seal...now my '97 Silverado
    runs like new.

  • @howardiko7156
    @howardiko7156 3 ปีที่แล้ว

    Harbor Freight has a plug cleaner that works better than any scrapping. All the V8 GM had a oil fouling of the rear plugs due to oil /sludge in rear return holes.

  • @tam1381
    @tam1381 3 ปีที่แล้ว +1

    Fuel trims ?.

  • @matthewnorton4529
    @matthewnorton4529 ปีที่แล้ว

    I need your help my truck with throw random miss fire and when I am at 60mph and pinch it I will get stumble like I'm running out of gas then I let off let the idle go down a little then start driving Normal again