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Truck shaking/odd idle after changing plugs and wires

midnightsilvy

By midnightsilvy
in Troubleshooting & Recalls

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midnightsilvy Enthusiast

midnightsilvy

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12 hours ago, txab said:

Why did you feel the need to change coils? Coils can last a good while. I'd put the old coils on and see what happens. Yo may have poor connection at the coil coming from the wiring harness. Where did you get the plugs? They could be counterfeit if purchased from Amazon and similar. What brand plug wires? Maybe they are crappy. Lots of things to look at.

maybe you knocked something loose. Maybe a wire somewhere got pulled

Long answer: my truck has almost 200k miles on it, was starting to see wear and mileage loss and decided it was time to change the plugs, and do the rest while I was at it. I live by Summit Racing and that is where I get my parts, they're MSD coils and wires with AcDelco plugs.

 

Short answer: I can do what I want with my truck.

 

On the other hand, the truck seems fine now, read misfire on cylinder 7 so pulled the plug out and porcelain broke apart. Replaced the plug, reconnected the wire and all symptoms, so far, seemed to have gone away

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Snowcamo Senior Enthusiast

Snowcamo

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38 minutes ago, midnightsilvy said:

 

Long answer: my truck has almost 200k miles on it, was starting to see wear and mileage loss and decided it was time to change the plugs, and do the rest while I was at it. I live by Summit Racing and that is where I get my parts, they're MSD coils and wires with AcDelco plugs.

 

Short answer: I can do what I want with my truck.

 

On the other hand, the truck seems fine now, read misfire on cylinder 7 so pulled the plug out and porcelain broke apart. Replaced the plug, reconnected the wire and all symptoms, so far, seemed to have gone away

Got bumped on the way in? 

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midnightsilvy Enthusiast

midnightsilvy

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Posted (edited)
33 minutes ago, Snowcamo said:

Got bumped on the way in? 

Very possible given 7 is back next to the steering column, bit hard to get the socket in there without bumping stuff. Also possible it broke coming out. Was either that or wire came loose after a couple days, like you suggested.

 

Either way, she seems to have cleared the codes herself and is back to normal, as of now.

 

Appreciate the advice!

Edited by midnightsilvy
Snowcamo Senior Enthusiast

Snowcamo

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19 minutes ago, midnightsilvy said:

Very possible given 7 is back next to the steering column, bit hard to get the socket in there without bumping stuff. Also possible it broke coming out. Was either that or wire came loose after a couple days, like you suggested.

 

Either way, she seems to have cleared the codes herself and is back to normal, as of now.

 

Appreciate the advice!

 

 

Rock on!

 

Here's a little trick.

 

Cut a socket like this down and remove the rubber inside. This is a tremendous aid in getting them in by hand, especially toward the firewall.

 

🍻 

20241228_122954.jpg

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asilverblazer Senior Enthusiast

asilverblazer

Posted
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Now you might as well take care of number 8.

 

Hint: Use a swivel/universal with long extension and attack from behind the AC accumulator.

 

Also, when diagnosing a miss fire on a particular cylinder. Try swapping the easily accessible parts from the bad cylinder to a known good cylinder, one at a time, to narrow down the culprit. The plug wire, then coil, then plug, then injector, etc. when the miss fire follows the part, you'll have found the problem. 

 

mikeyk101 Senior Enthusiast

mikeyk101

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42 minutes ago, asilverblazer said:

Now you might as well take care of number 8.

 

Hint: Use a swivel/universal with long extension and attack from behind the AC accumulator.

 

Also, when diagnosing a miss fire on a particular cylinder. Try swapping the easily accessible parts from the bad cylinder to a known good cylinder, one at a time, to narrow down the culprit. The plug wire, then coil, then plug, then injector, etc. when the miss fire follows the part, you'll have found the problem. 

 

It's been a while since I did mine but I seem to remember I did mine from underneath. I had to do it blind by feel though.

midnightsilvy Enthusiast

midnightsilvy

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49 minutes ago, asilverblazer said:

Now you might as well take care of number 8.

 

Hint: Use a swivel/universal with long extension and attack from behind the AC accumulator.

 

Also, when diagnosing a miss fire on a particular cylinder. Try swapping the easily accessible parts from the bad cylinder to a known good cylinder, one at a time, to narrow down the culprit. The plug wire, then coil, then plug, then injector, etc. when the miss fire follows the part, you'll have found the problem. 

 

I just ended up taking out the well liner and wheel and went from there, though getting the liner back in right wasn't too bad I wouldn't want to do that again. What you said would likely be easier.

 

As for the misfire, yeah that would make sense, but just ended up changing the wire and plug and it went away in my case.

Jsdirt Senior Enthusiast

Jsdirt

Posted
Posted

I saw your post a ways back & have to comment on it - DO NOT EVER go to the dealer for ANYTHING with a 2018!! Dealer service departments are for warranty use ONLY. Trust me on that one. Save yourself a pile of cash and a gigantic headache and go to a private name shop with good ratings in the future.

 

I've seen quite a few brand new plugs with cracked porcelain on the V8's that are tightly packed in. Usually it happens when trying to remove the socket - people get impatient, and start yanking on the extension. Doesn't take much at all these days to put a TINY hairline crack across the porcelain and cause a misfire.

 

First time I worked on the new (2010) Camaro I cracked one! 

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