Hard shifting caused by an ignition misfire ? Yep ! 5.3 Suburban Misfire & Diagnosis!
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- Опубліковано 9 лют 2025
- Cylinder #4 Misfire causes transmission line pressure to max out. Why is it misfiring?
Silverado Sierra Suburban Yukon Escalade Avalanche 4.8 5.3 6.0 6.2
#keepwrenching #wesselmotorworks #wrenchingwithkenny
Very good video. I have a 2019 Suburban and at 105,000 miles had a #2 cylinder misfire and a very rough idle and ABS & traction control lights lit up. I found broken motor mounts and my battery died and wouldn’t hold a charge. I bought new plugs and wires, replaced the motor mounts and installed a new AGM battery. Runs like a new vehicle with much improved acceleration, starts instantaneously and idles like butter! By the way the AC Delco wire kit came with those tin sleeves that help keep the heat off of the boots. After spending way too much time on the first four spark plugs i went to Harbor Freight and bought a 3 piece set of those spark plug boot pliers. They are worth their weight in gold! My Suburban runs like a new vehicle now, starts better and accelerates harder. I had brought it to my local mechanic first, but they suggested a fuel system service for $450.00, new plugs and wires for $500.00, new motor mounts for $2,000.00 and new battery for $439.00!! Yikes! That’s north of $3,000.00 to fix a rough idle. That motivated me to spend about $500.00 total in top shelf parts and a rather long day contorting myself over, under and around the front end of my SUV. I am so glad i did the work myself and saved a lot of cash. A couple of the plugs were a little difficult to change out, but i got it done. One little tip, when replacing the plugs and you can’t even get close to seeing the hole they go in… when you remove each plug pay attention the the angle the socket drive is at and replicate that angle to find the hole easier. Also, when you put the spark plug in the socket surround it with a little bit of paper to keep the plug held very tight in the socket to keep it from falling out. of the socket until you get it installed properly. Works like a charm and is very easy to remove after you snug the plug down to the proper torque. Apparently, a bad battery and bad spark plug wires can give you all kinds of faulty codes. Another tip is I installed a Valvomax drain plug… it makes oil changes easier and much less messy.
These videos make me feel at home, keep them up, thank you
Thank you for that comment ! I really appreciate that !
I have to thank you I had the exact problem with my 07 Silverado, I changed the plugs and wires and it is running stronger and shifting smooth. 👍
Thats a nice soft pad for creeper replacement,makes it easier on us older guys,you are right Kenny,computer senses misfire,raises line pressure from trans pump through the pressure control solenoid to keep from burning up clutch packs and shifts very hard,cleaning up the misfire proved that without a doubt!!
That's a good tip about the home-made topside creeper. It's compact so it won't take up room in the garage.
Yea !! Those actual underhood creepers are great , but take up alot of room , and they're expensive to boot !!
I have something similar: it seemed a bit expensive at the time but it has lasted over 10 years. I mainly use it for laying under my car; I now use knee pads when kneeling down as these move with you and you don't have to keep repositioning the mat.
I like how you put things together correctly, speaking of the metal sleeve protectors for the plug boot ends. I really like your work and knowledge you share
Thank you so much it fixed my truck shifting hard with new plugs and a coil
Actually makes perfect sense. Shift strategies are dependent upon load/ maf, manifold air pressure which during misfire will appear in live data as a loss of vacuum...meaning the interpretation by the pcm is that the throttle blade is wide open and atmospheric pressure exists even if momentarily as though the vehicle is in W.O.T. operation, then meaning that as the software programming will show, wot shift strategies have significantly increased line pressures as one would expect and the trans hits hard but without the normally accompanying torque numbers needed to smooth the shift itself....meaning BANG SHIFT. Multiple technical service bulletins from GM exist for trans shift complaints just based on contaminated mass air sensors from aftermarket oiled air filters which immdiately affect load tables which is what just about every table uses as it's y axis for reference.
Had that happen to my 07 avalanche more from 1st to 2nd. Multiple random misfires. Traction control light on and Changed wires and plugs and fixed it.
Kenny...I really, really like the way you perform mechanic work and the way you do your videos! Very good! I will be a fan for life. Thanks.
Thank you very much! I appreciate your kind words. Keep wrenching 🔧
Awesome video! Thanks for all the help.
Thanks for watching !!
Great video Kenny! I'm glad that you ordered the shields- pretty important for longevity on these I have also found that they aid in pulling the wires off the plugs without tearing the wires. When i get a misfire on a 2007+ 5.3 on cylinder 1,2,4,or 7 i usually suspect a collapsed AFM lifter first and spark second. Most of the misfires i see tend to be lifters. I will do the flood clear crank and listen to starter cadence to start my diag. Glad it was a simple fix!
On locomotive EFI systems, we used to see a misfire cause a "sympathetic failure" to other cylinders. A locomotive diesel engine needs to maintain a constant RPM at different throttle settings. There were 8 different throttle positions plus idle. If one cylinder misfires, then the EFI computer would sense the decrease in RPM and overfire the next cylinder or two in the order to make up for it. We had the luxury of being able to selectively fire each cylinder to find the source of the problem with a laptop.
Padding! What a great idea! I noticed all of the battle scars that saved you from getting punctures and scrapes. This year in spring, I picked up a pack of 4 anti-fatigue mats from Harbor Freight to walk on and found that they're great for crawling underneath too. That was the beginning of a love affair for under 10 bucks. Needless to say, I went back for more with another coupon in hand. I am making a "civilian" console for my Police Interceptor Explorer out of baltic birch plywood and I bought another pack to use as padding for the armrest cushion. I got some upholstery material to cover it. Not as thick as the garage door insulation but it feels sooooo good on the garage floor! Can't wait to sink my elbow into that cushion on top of the new console!
That sounds totally awesome !!
Thanks for the great video, I have 08 GMC doing the exact thing, code p0304, im gonna change out the wires & sparkplugs and hope that fixes the problem.
my Jerking problem was bad bad ignition coil thanks bro great vid 👍
I felt it lmao. Na foreal I've been working on my Silverado it has the amf 5.3 correct I thought I had a collapsed lifter but turns out it had spun around and was catching causing the lifter to stick. Also in cylinder 4. Code was P0300 only code my computer would read but my buddy's would read p0300 and p0304 I had blue smoke out of my passenger side exhaust note the truck has duel's. But I got lucky and was able to save the lifter. The check ingane light wouldn't just come on it would continuously blink. The truck is a 2008 but it's all the same pretty much when it comes to afm and dod vortecs
Kenny, I just replaced my plugs and wires on my 06 avalanche with the 5.3L due to the number 4 plug wire, right where the wire enters the spark plug boot was dry cracked and was hanging by the internal wire and was arcing a 1/4” gap. My plug wires had the tin sleeves and 6 of my wires just broke at the plug boot when I barely touched them. Two of the boots left the internal terminal on the plug and 3 of them the boot just tore in half.
That wire burned up because it’s the wrong set of wires for that engine. They’re obviously not factory wires but the issue is that they’re supposed to be 45 degree boots and the metal boot sleeves are missing.
I had an 85 Cadillac DeVille that shifted really weird when the spark plug wires went bad. The first time it happened I thought the trans was done, but wires took care of the problem both times it showed up.
Great video Kenny- just wondering how many years you been wrenching and where you got your mechanic education? You definitely know your stuff.
I've always had a thing for mechanical things. This goes back to when I was a little kid. My dad wasn't a mechanic, but he was handy with things. In the beginning, I basically learned by doing. I read every car magazine out there such as Hot Rod, Car Craft etc. . When I was 14 I bought a 69 AMC Javelin and tinkered with that. I just had a natural knack for it. When I was a junior in HS, I was able to get into the Auto Shop program. We had a pretty big shop with several lifts. It wasn't long until the teacher realized that he wasn't teaching me anything I didn't know or that I couldn't figure out . He actually would have me work on his car while he taught class LOL . I got a job as a helper at a shop as soon as I was out of HS and they realized I could figure stuff out and do whatever they had in the shop. After 4 years , I opened my own shop and was doing quite well. After a successful 7yrs, I suddenly and unexpededly lost the lease on the shop, so I took a job with a full line Chrysler & GMC dealer . I was there for 22 years and received training from them. But honestly, as soon as class was over, I forgot what they taught. I learn by doing, not in a classroom. For the most part, I consider myself self taught. Thanks for asking !!
I got the po1307 code for a no.7 misfire. The actual issue was a loose plug and plug wire. Check those first
Thanks for the video I learn something new
Kenny I also have a 07 Escalade with the 6.2L and those wires did the same thing with the plug wires just breaking apart or tearing in half on the plug. Although, there is no sense in swapping one wire or one plug though, the wires are prone to tearing apart and breaking plus if one plug is fouled personally I swap them all. No use in having a miss later from the old plugs after a one plug repair.
Those shields come with the AC Delcos. I changed mine and they didn't have any Delco wires in any parts store. So I told them to give me aftermarket and they dont come with shields. So save your shields from the original ones if you buy aftermarket. They do work for heat protection.
Got a Caravan with a 3.3 V6 given to me because my friend's mechanic told them their van needed a transmission. I drop the trans pan and didn't see anything obvious except dark fluid. I replaced the filter and fluid and drove it over a hundred miles home. Majority of those miles were highway and the car performed well. Once we started using it locally we thought maybe it wasn't shifting quite right and that was partially because of the mechanic saying it needed a trans. I then thought maybe it was a miss and replaced the plugs. It started driving better for a bit but I noticed three of the wires had the metal head protectors and three didn't. I got a new set with the protectors and installed them. The back three were a bit of a pain and that is why the previous mechanic didn't install them. Once installed the trans shifted like a charm and the slight miss going up hill or passing was gone. Go figure. Good video and Merry Christmas.
If u scan it with the obd2 option, itll show which cylinder(s) are misfiring. On the snapon scanner i should say.
Tell the customer it is a good idea when changing plugs to also change the spark plug wires or ignition coil boots, depending on which ignition system the vehicle has. The boots get worn out from heat. Of course, it helps when those heat shields are installed on the boots too.
Great anest mechanic not to mini mechanics do like this great Man thanks 👋👍
Hey Kenny, I don't understand: these spark plugs are resistive so the spark plug wire and plug together have a resistance greater than the gap. This is so the operating conditions of the coil are consistent despite the changes in heat, air-fuel destiny, etc that causes the voltage needed to arc the gap to vary.
So the current arcing a large gap directly from the coil terminal to ground doesn't demonstrate anything about the condition of the plug.
Correct. Thanks for watching & keep wrenching 🔧
The AFM-DOD stuff, makes the tranny module SEEK when to shift depending on V8 or V4 mode.
That craziness is why I bought and plugged in an AFM Disabler (OBD2 Dongle).
It keeps the engine in V8 mode all the time and saves a lot of BS.
I would absolutely do the same thing. Thanks for your comment & watching the channel. Keep wrenching 🔧
My truck was doing this took to chevy dealership and spent 4000 for new head still does the same thing. If I go get new wires and it's fixed I'm using your video to get my money back.
what was it
The people need to know how it went @welder878 hahaha
What about when the scanner says cylinder 6 misfire and valve spring... is that just the seals?
5.3L with a misfire on #2. Change of Coil, wire, spark plug. Still misfiring switched fuel inject from 4 to 2. Still no luck. Compression test 120 to 145. Across all 8. I'm not sure what's causing my problems.
Okay so I think I have the same motor and transmission on my 2000 Chevy Silverado z71 5.3.
Hard fist first gear or second. Lol
But there’s no check engine light .
Kenny, what should I see on the spark advance on my code checker? I've got 17 degrees at idle. Runs a little rough at stop light and having issues with 1500 rpm at 55 mph.
Harbor freight and tractor supply Walmart have folding mechanic mats $20 vs getting $60 garage insulation unless get it for free . I have several in cars and I take to the gym as a portable mat
That’s how my truck is now
I need help on mine, I’ve been working on it myself. I have a Misfire on Cylinder 4, Coils, Plugs & Wires and all fuel injectors were checked and replaced. I have a flashing Check E light On. I have compression on all cylinders. And no luck. Same misfire on Cyl 4 Code and the truck is shaky. Any help? Thanks.
my traction control and stabilititract lights come on also and engine light flashes and just has generic p0300 code also
@frankgrimes1385 Hi, It's Mrs Wrenching! You should go on the Facebook group Backyard Mechanics (answer all the questions) put the year, make & model of your vehicle in your post. Be sure to include what is happening with your vehicle & what you have done to fix it so far. There are a lot of techs that may be able to help. The link is toward the bottom of newer videos. Keep wrenching!
The spark from my coil looked pretty lethargic. Guess when I don’t have a huge rain storm coming, I will swap coils and see what happens.
What does DTC stand for on the scanner? I have a scanner still trying to learn some things about it.
Diagnostic trouble code
What kind of scanner do you recommend for the average do it yourselfer?
Did u ever do a fix on the Evap leak
I did not . That code never returned so I'm thinking the customer may have left the gas cap off at some point
Lol easy fix we all look for ,my stilbiitrack turning off a flashing cel maybe my sterring wheel sensor or tbp code is 304 ,but new pulg ,wire,and coil,f inj all good , abs,masf,allgood
Sorry why do you put the customers car threw two and three times we already seen it ! I like your videos don’t take it the wrong way .
I think you have a 2007 not a 2000 as you stated at the start. 🙂
Yea , I definitely misspoke on that . Good catch !!
@@WrenchingWithKenny good show and easy to watch, lots of good info.
Sounds like a deer hit
My 2006 chevy hard shift when I been driving for awhile. I pull over and cut it off for a minute or two and transmission shift great again. Can you give me some advice it's a 5.3 truck new spark plugs new wires.