Engine stumble after spark plug change

Well the title says it all - I changed my plugs this afternoon and now I have an engine stumble or stutter.

I gapped them to .041 prior to install. Oem plugs bought from the dealer. I followed most of the instructions in the post by Chris4x4, there was a thing or two I didnt disconnect.

I don't have a code reader. I also don't think it's a cylinder misfire, because I didn't get a check engine light, until I pulled the plastic wiring harness off of one of the plugs - I was checking the sound of the engine to confirm to my ears thee wasn't a cylinder misfire.

It feels like the engine now is getting too much or too little fuel? That make sense?

Is it relevant the old plugs were gapped at .045?

Not sure what to do here and would appreciate any suggestions. I have checked all the connections, but will check again now.

Thanks.

 

Yep....definitely check all your connections. If one isnt connected all the way.......youll have a misfire or stutter. If its still doing it after checking connections.....may have to pull the plugs one by one. Ive seen a cracked plug...new....do it before.

 

Ok all connections are checked and I still get the same result. I also disconnected the battery for a few minutes. I should say that it is more 'running rough' than an actual stutter. It strangely seems fine when there is no load on engine - I can rev it up with no stutter or roughness - however when I put it into gear it is rough immediately.

I should also say, that when I removed the coils on the passenger side (I did it first), I accidentally also removed the three bolts that are beside the coils to the left. Chris 4x4 has an excellent pic in his instructional post. When I realized my mistake I reinstalled them immediately. I forgot about this in my first post and hope this is not the cause of the problem.

Is it possible that because of the difference in gap between the new and old plugs that the timing or something could be out as a result?

Thanks fellas.

 

Also if it was a misfire wouldn't it throw up the check engine light?

 

I was careful with the anti seize no to torque wrench cause mine didn't fit (long story). I used my best guess

I'll start pulling plugs to look at them.


Thanks for your time.

 

You guys were right, it was a broken spark plug. Thanks a lot for your help

 

Glad you found it and can get it squared away easily.

 

So get this - yesterday I bought a new plug to replace the broken one. Inspected it, replaced it no problem. The plug looked good, I mean I wasn't expecting to have another broken plug. Start up the truck, sounds fine. Leave it for awhile.

Last night, off on a chocolate run for the missus, boom same damn stumble but not as bad as the first time. Get home pull the new plug and it's got a really small crack in it too. I pop one of the old ones back in and it's fine.

Wtf? Bad batch of plugs from the dealer?

 

Or you could have cracked them on install. Easy to do. socket and extension needs to be centered in bore at all times. I never use a spark plug socket. some of them have a device to hold the plug in at the top. Moving the socket around during install can crack the porcelain. I doubt you got 2 bad plugs.....

 

I'll try again tomorrow when I can pick up a new plug. This last time I was very careful, but maybe not careful enough.

When I realized I had to recheck them all, I sorted out my torque wrench problem so now I know they are all torqued to 15lbs.

 

hey man, I'm not trying to be a now it all, but I learned from the best, (Grandfather) all you need to do is snug it. turn them in slowly and give it one snug, that all.
all my years never had a problem, doing it, never had one run out, or blow out.

 

,
Snug here too 1/8th turn at most, never any problems.

 

Not at all man, appreciate the advice, cheers.

 

Probably this. I was showing my sister how to change her plugs (I was letting her do all the work and just supervising) and somehow she cracked 3 of them. I think she got a little overzealous trying to get the socket off the plug.