Easy DIY for spark plugs turned into horrible, horrible nightmare

Niklaus

Original poster
Member
Apr 18, 2014
37
Hello all,

Sorry for the long read. This is how my Easter weekend was ruined.

Well I was getting terrible mileage in my Envoy, like literally 8-10 mpg city and 12-13 average however normal highway 21-22 so I decided that it was time for me to change my spark plugs since they are probably original, never changed with 123k miles on the car which is terrible. I wasn't too sure if the poor mileage was because of this but I also felt that I was lacking some power.

Note: I bought this car not too long ago as the second owner.

I was watching a video on youtube by MAY03LT and it really did seem easy and not that complicated. I decided that I should have a go at it. Well the whole thing turned into one entire nightmare for me and I have no idea how to recover from this. First thing's first, the last 2 cylinders were extremely corroded and the spark plugs were in terrible shape. I had to use too much force to remove it and a lot of rust was left on the thread inside of the well. I did get the spark plugs out but I was afraid some rust could've fell in the well into the cylinder. Next thing, I started to replace the spark plugs and the last 2 would not want to go in, it would get very tight very fast and I knew this was because of the corrosion. A mechanic I called at this point said he wasn't interested in helping me and I was screwed. He however told me to use WD-40 and keep on twisting back on forth to get the plugs in. This worked but I was scared that the WD-40 would screw with my engine which I hope it didn't. I managed to get the plugs in and put the coils back in and tried to fire up but I had a terrible misfire which turned out to be the 5th plug not in tight enough. I fixed that but then I was getting rough idle at 1000 rpm or lower, with the roughness increasing.

I took out each spark plug one by one to re-position them to make sure they were not loose and that's when reality turned into a nightmare.

The 3rd spark plug for the 3rd cylinder had some of the ceramic/porcelain part break off and fall into the well, down into the cylinder. I couldn't believe what had just happened and I know I am completely screwed.

I am lost, and very very stressed at the moment. Honestly. The mechanics I called said they can't help me because they don't have the tools and one of them said to call the dealer.
Dealership offered me a fix, for $2396.40 not including tax. He said the whole engine had to be taken apart to get access to the cylinder head and this would take 3 days of labor.

I am stuck. I have been trying with a small shop-vac and a plastic hose taped together getting into the well to suck out the ceramic/porcelain. At this point I took out two pieces but I have no idea how many more pieces there are. The shop-vac is giving me a hard time because it feels too weak. Guess my car will sit for a while.

Anyone offer any thoughts or advice? I really need it, and thanks a lot in advance. :lipsrsealed:

EDIT: I am using AC Delco 41-103's

2002 GMC Envoy SLT
123K Miles
4WD 4.2 I6
 

Niklaus

Original poster
Member
Apr 18, 2014
37
Thanks man.

My brother is trying to get as much out as he can but he claims he can't find or see or get any other pieces and they might've been crushed already.

Question; What would happen if I put in a new spark plug and fire it up even with a tiny bit of ceramic still left there? Could it be removed through exhaust?
 

Trios

Member
Mar 27, 2014
237
Well, you seem to have gotten yourself in a bit of a pickle!

I can't explain what happened to the porcelain on the plug. However, I do need to let you know that you need to stop worrying quite so much about tiny things in the cylinder. Yeah, it's not good, but a bit of rust falling in to a cylinder really won't destroy the engine on startup.

I would buy a thread chaser (NOT A TAP) and go through all the spark plug threads to clean them out properly.

WD-40 will not harm your engine. It's a perfectly legit solvent for this task. You can use a penetrating oil or PB blaster with your thread chaser as well; try and get the threads clean.

Then, on cylinders where you're worried about stuff having fallen in, rotate the crank manually until that piston is at/near TDC and then try and vacuum it out with your tube. Get as much as you can, and don't worry about the little stuff that may be left. In the military, they routinely break the tips off of glow plugs on the 6.2 diesel engine and just let the motor eat them; that's about a pencil width worth of metal bouncing around in a cylinder until it makes its way to the exhaust. Now, this isn't a diesel, but a speck of rust isn't going to cause harm.

Then clean up your plugs and replace any that appear damaged, and use a speck of anti-seize on the threads when you reinstall them.
 

The_Roadie

Lifetime VIP Donor
Member
Nov 19, 2011
9,957
Portland, OR
Welcome, and sorry we had to meet under these circumstances.

All parts stores, and especially Harbor Freight for cheaper, sell inspection cameras. For $150 or less. Here's one on Amazon for that price:
Autel (MV400-5.5) Digital Videoscope with 3.5" Screen and 5.5mm Head

View attachment 34304

So you can look inside any cylinder to check for debris.

What I would do is use compressed air and a small blowgun inside the cylinder to blow debris around and with the positive pressure in the cylinder, it should exit through the spark plug hole. You should be able to buy a compressor for well under $100 on Craigslist or the same sort of parts stores or Home Depot.

View attachment 34305

Surely your mechanics have such tools? If not, perhaps they just think you want it fixed for $50. That's not a possibility. But $2300 is insane. Prepare to buy some tools, and that's never a bad thing. Remember, he who dies with the most tools wins. :wink:
 

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RayGumm

Member
Apr 16, 2014
630
I was just getting ready to give my 2 cents but Roadie (graciously) did it for me! :yes:

I had something of a similar issue a couple years ago in an old Mada MX3. Seems the idiot mechanic who worked on the car for the previous (and original) idiot owners used an AIR POWERED IMPACT WRENCH to torque down the plugs, cross threaded one, ran it home anyway, and when he discovered it, instead of doing what he should have and replaced the head for free, HE JUST WRENCHED IT DOWN SOME MORE so it wouldn't outright fall out.

Fast forward a year and a half and I was toolin around pushin the thing a bit too hard and I hear this *wham!* under the hood, instantly lost about 1/4 of my power and had a wicked misfire, not to mention a really ominous hissing sound once every revolution that timed up with the misfire.

Great - I thought I blew a head gasket.

Nope. Found the plug wedged INTO the hood brace, replaced it only to find the hole stripped. Bough a $40 'sav a thread' spark plug ream & tap kit with a sleeve, tapped the hole out without removing the head, used a shop vac with the micro tools set (awesome purchase if you don't want to buy the compressor, BTW) and engine parts cleaner to suck AND blow all the bits of aluminum that fell into the cylinder, replaced the plug with the sleeve to fit the new, slightly larger hole, and voila - problem fixed. Gotta say, that was the scariest time starting my engine - I just KNEW i left a huge chuck of metal in the cylinder and would end up destroying the cylinder, head, or wall, but nope. Fired right up with no worries.

I would HIGHLY recommend the camera, though. If, for some reason, you simply cannot afford/borrow one, I would feel 80% confident that if you blow and suck out the cylinder at TDC with a compressor or high powered shop vac with the micro tool thingie, you should be fine. Engines eat crap all the time and don't die, but it's best not to push your luck with something like porcelain.

Good luck, man!
 

MAY03LT

Member
Nov 18, 2011
3,412
Delmarva
Niklaus said:
The 3rd spark plug for the 3rd cylinder had some of the ceramic/porcelain part break off and fall into the well, down into the cylinder. I couldn't believe what had just happened and I know I am completely screwed.

Hey. You've already got some SOLID advice from these guys, so there's not much that I can add. How much of the plug do you think fell into the cylinder? A pic of the remains of the plug would be helpful.
 

Niklaus

Original poster
Member
Apr 18, 2014
37
MAY03LT said:
Hey. You've already got some SOLID advice from these guys, so there's not much that I can add. How much of the plug do you think fell into the cylinder? A pic of the remains of the plug would be helpful.

Well, my brother is a life-saver. He got a lot if not everything out. There were literally about 8 pieces and I was almost positive there was some stuff left since not all the broken pieces fit the plug but I then I remembered that there was some of the plug that came out when I unscrewed it. Maybe some tiny pieces or powder were left, but I gave it a shot. I screwed in the spark-plug and hoped for the best.

Well, everything started and I was relieved. Seems like all the ceramic came out, no grinding or anything weird.

However, back to square 1. Engine began to idle rough once it hit 1000 RPM and I drove it down the block and back to see what would happen but it actually got a little worse.
One of the cylinders is still misfiring, and it smells horrible (experience from my dad's 2002 TB). I know I am cooking my catalytic converter driving but I think I will just take it in to a shop since I don't want to mess around with it anymore. Light was flashing (major fail) but then it stayed on when the misfire calmed down a bit.

I honestly think it's cylinder #4 and the coil pack because it was completely corroded. I will get it diagnosed tomorrow.

Thanks everyone so much for adding your thoughts! It helped a lot and I felt a lot better and gained some motivation :smile:
 

IllogicTC

Member
Dec 30, 2013
3,452
Grimor said:

I was just going to suggest that very thing. Got one along with an inspection mirror and magnetic pickup (those wouldn't help for this situation though) for like $7 at Wal-Mart.

When you did the spark plugs, did you also take the chance to clean the throttle body, and reset the PCM to account for that? And a corroded coil will probably stick you like that with the misfire...
 

Niklaus

Original poster
Member
Apr 18, 2014
37
IllogicTC said:
When you did the spark plugs, did you also take the chance to clean the throttle body, and reset the PCM to account for that? And a corroded coil will probably stick you like that with the misfire...

Yep, did that because it was along the way. Used some mediocre brand throttle body cleaner. It wasn't really that dirty to begin with which surprised me! :thumbsup:

Odd thing is that while idling it seems like it's closed or barley open at all. When I floor it in park the revs only go to 3,500 or so and the throttle body doesn't open a whole lot. Not sure if this is normal but all I felt was a misfire not a suffocating engine.
 

Wooluf1952

Member
Nov 20, 2011
2,663
Milwaukee, Wisconsin

MichEnvoyGuy

Member
Dec 3, 2011
522
Whoa whoa... lets take this down a step:

You say cylinder #4 was really corroded -this a lot of us here are familiar with. Water drips down from the hood seal, onto the valve cover and makes it way into #4 spark plug well. For this reason, the #4 coil goes bad more than the others. There was even a TSB out on this, IIRC.

BEFORE throwing in the towel and bringing it to a shop, swap the #4 coil to another cylinder. See if the misfire changes cylinders.

I have money that your #4 coil went bad. It was probably on the fence before you touched it, after disturbing it to remove the spark plugs, it shit the bed.

If thats your only problem (cyl #4 misfire) you are doing good. Get that resolved and you did a good job after all :thumbsup:
 

shaun4282

Member
Jul 5, 2012
8
Hey Niklaus, what did you ever find out? I had the same problem with my tblazer today! No lights on, misfires or changes in oil pressure. I also cleaned my throttle body, pulled #10 and #28 fuses thanks to May03's video (thanks by the way!) and it started idiling weird but I have read that it is normal after cleaning since the system has to 're-learn' to adjust to the clean t-body. I'm still erring on the side of caution and taking it to a mechanics to have them check it out just to be safe. Sorry you had to have your easter weekend ruined like that :frown:
 

Mounce

Member
Mar 29, 2014
13,667
Tuscaloosa, AL
shaun4282 said:
Hey Niklaus, what did you ever find out? I had the same problem with my tblazer today! No lights on, misfires or changes in oil pressure. I also cleaned my throttle body, pulled #10 and #28 fuses thanks to May03's video (thanks by the way!) and it started idiling weird but I have read that it is normal after cleaning since the system has to 're-learn' to adjust to the clean t-body. I'm still erring on the side of caution and taking it to a mechanics to have them check it out just to be safe. Sorry you had to have your easter weekend ruined like that :frown:
if you pulled the correct fuses for the throttle body cleaning then there is no "re-learn" period. Pulling the fuses or disconnecting the battery resets the pcm to compensate for the clean throttle body. How long did you leave the fuses out?
 

tbyoda

Member
Apr 19, 2013
187
When you clean the TB you need the pcm to relearn TB positions. Fuses 10 & 28 are the right fuses for the pcm. Sounds to me that he followed May03lt video. The engine will idle ruff for a min while the pcm goes through the relearn and throw codes, CEL but they will all go out. If you don't do a relearn there no benefit to the cleaning.
 

Mounce

Member
Mar 29, 2014
13,667
Tuscaloosa, AL
Well when I cleaned mine there was no rough idle or cel afterwards. The reason that the fuses are pulled is to reset the pcm because it learns how to change the tune due to the throttle body getting dirty over time and when you clean it, it will still be tuned as dirty unless you reset it. Then you're on your way with no problems. If you don't pull fuses/disconnect battery then it takes it x amount of engine cycles for the pcm to learn that it's clean and tune everything properly.
 
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The_Roadie

Lifetime VIP Donor
Member
Nov 19, 2011
9,957
Portland, OR
Mounce said:
Well when I cleaned mine there was no rough idle or cel afterwards.
That behavior is unusual, and not supported by what we know about the adaptive algorithms in the PCM. Some folks require an hour of city driving, stop and go, to get good idle behavior back.
 

IllogicTC

Member
Dec 30, 2013
3,452
Mine idled high for a time and brought itself down, and driving put it right back at a beautiful ~615-625 idle when warmed.
 

Mark20

Member
Dec 6, 2011
1,630
Welcome aboard!

A curiosity, would removing the air injection solenoid let any small things that might have been left behind in a cylinder blow out before they hit the cat or muffler?
 

MAY03LT

Member
Nov 18, 2011
3,412
Delmarva
shaun4282 said:
I also cleaned my throttle body, pulled #10 and #28 fuses thanks to May03's video (thanks by the way!) and it started idiling weird but I have read that it is normal after cleaning since the system has to 're-learn' to adjust to the clean t-body. I'm still erring on the side of caution and taking it to a mechanics to have them check it out just to be safe.
Thanks for the shout out man.

I've heard all kinds of stories about what to do for the relearn. I've done enough of them over the years that when it's all said and done, an 8 mile road test is all I do now. 2 on the backroads to the highway, 4 on the highway, and 2 back to the shop.

As stated, give it some time. The last thing you should do is let someone who probably doesn't understand our platform look for a problem that might not even exist. A good example is the Chevy dealer near my work does not clean throttle bodies. They replace them.
 

The_Roadie

Lifetime VIP Donor
Member
Nov 19, 2011
9,957
Portland, OR
MAY03LT said:
The last thing you should do is let someone who probably doesn't understand our platform look for a problem that might not even exist. A good example is the Chevy dealer near my work does not clean throttle bodies. They replace them.
Did Vertical Scope just expand their empire to start buying up Chevy dealers? What an evil and criminal thing to do to poor innocent owners!
 
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glfredrick

Member
Jan 14, 2014
172
Mark20 said:
Welcome aboard!

A curiosity, would removing the air injection solenoid let any small things that might have been left behind in a cylinder blow out before they hit the cat or muffler?
Nothing to worry about. Anything small enough to blow out through the exhaust valve (lifts about a quarter inch) will not effect anything downstream. And the good news is, if it is not small enough to blow out through the exhaust valve, it soon will be. The constant pounding and tumbling will reduce most anything in the cylinder to nothing in moments. That piston is going up and down hundreds of times a minute under FIRE (heat and pressure). I've seen times during engine disasembly when a piece of valve broke off and really tumbled around inside the cylinder -- that makes a mess -- but most anything that a spark plug might shed and that also fits through the hole won't really matter.

And, for your question... No. There is only one way to remove something from the cylinder -- the exhaust valve and then down the exhaust pipe.
 

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