Vehicle feels slightly more sluggish after new spark plug change

[apollo18]

Hey all replaced the spark plugs in my 4 banger. Replaced with oem from rock auto that matched the exact same ones that came out. Was the denso 3417
I didn’t have a gapping tool so didn’t care to check the gap however I used a torque wrench and the install went great. Fired it up and it sounded good and I noticed the idle was pretty smooth.

Tbh the old plugs looked fine but they were in there for 110k miles so were gonna need a change soon anyways.

Took it for a drive and everything feels normal. Idle is smooth, sounds good. However idk if it’s my mind but I feel like the acceleration is a bit sluggish. No engine light

It could totally just be my mind making up things like maybe I was expecting a performance increase and this is probably more or less the same as how It was before. Mayne it’s all mind game. If I put it into first gear and give it a rip it feels smooth and good.

The more I drive it I’m starting to think maybe it’s just the same as how it was before. Is there anything I can do to bring some more peace of mind? I tbh don’t want to take it apart and check the gap. They were brand new from rockauto in a 4 pack so I doubt they were opened or dropped and I am certain I didn’t do anything wrong during install.

Or do all my findings and signs that I outlined above Indicicate all is well and even if gapping was an issue then the findings would have been worse?

Thx

 

[dumkid]

Smooth? Don't worry about it. The electrode could be pointing different directions so you could try indexing your spark plugs to gain that 0.1hp

 

[dubber09]

RA normally lists both recommended gap and plugs' factory pre-gap, check those to put your mind at ease.

 

[atikovi]

I didn’t have a gapping tool so didn’t care to check the gap however I used a torque wrench and the install went great.

You have a torque wrench but not a $5 gap tool? Always check and if necessary adjust the gap before installing.

 

[Propflux01]

Since it’s an iridium plug, it’s probably gap set from the factory, and can be damaged very easily trying to gap them. I’m pretty sure it is just your expectation of more power that is keeping you up at night. The plugs that came out were probably still good enough to lit off regularly. Unless they were missing and worn beyond worn, you won’t notice much, if any increase.

 

[atikovi]

Since it’s an iridium plug, it’s probably gap set from the factory, and can be damaged very easily trying to gap them.

One plug is used in hundreds of applications, all of which may have a different gap spec. A proper gap tool won't damage anything.

 

[PF52]

One plug is used in hundreds of applications, all of which may have a different gap spec.

Regular copper plugs, sure. But every use I see a Denso 3417 specified for calls for 0.044".

 

[supton]

When you pulled the plugs, how clean was the insulators? I'm wondering if you have a valve cover gasket leaking a bit, maybe, and maybe some oil drained in.

Otherwise, it could be the weather... or hopes that new plugs added the same 10hp that some racing stickers on the windows do.

I'd leave the old plugs on the bench for now. If power still seems off after a week or two, maybe pull and compare, or put the old plugs back in and see if that missing power is back. Maybe you got mismarked plugs, or returns, or bad in box ones. But if it's a very slight difference, I'd be tempted to run it for at least a bit.

 

[atikovi]

But every use I see a Denso 3417 specified for calls for 0.044".

From the website,

3417 is pre-gapped at 0.043 inch from the factory. However, the gap must be adjusted for the vehicle that the spark plug is intended for.

 

[zzyzzx]

Computer relearn peroid?

 

[Dave9]

Hook up a scan tool and look for misfires. If there are none, then it was all in your mind, unless you disturbed some vac line and it's now running lean from a minor leak. Check fuel trims with the scan tool, one capable of live data of course.

 

[Escape08]

Fake https://www.toyota-4runner.org/4th-gen-t4rs/280391-counterfeit-spark-plugs-hats-off-rockauto.html

 

[apollo18]

When you pulled the plugs, how clean was the insulators? I'm wondering if you have a valve cover gasket leaking a bit, maybe, and maybe some oil drained in.

Otherwise, it could be the weather... or hopes that new plugs added the same 10hp that some racing stickers on the windows do.

I'd leave the old plugs on the bench for now. If power still seems off after a week or two, maybe pull and compare, or put the old plugs back in and see if that missing power is back. Maybe you got mismarked plugs, or returns, or bad in box ones. But if it's a very slight difference, I'd be tempted to run it for at least a bit.

ty it was all clean, i think its just my mind

 

[apollo18]

Fake https://www.toyota-4runner.org/4th-gen-t4rs/280391-counterfeit-spark-plugs-hats-off-rockauto.html

if it was fake wouldn't it run like trash? like bad idle and everything?

 

[apollo18]

Hook up a scan tool and look for misfires. If there are none, then it was all in your mind, unless you disturbed some vac line and it's now running lean from a minor leak. Check fuel trims with the scan tool, one capable of live data of course.

ty ty if i can get hands on one i will but tjhe more i think of it its prob just my mind

 

[JustinH]

I don't gap the iridium plugs either. My GDI Tuscon needs plugs every 30k so I just toss them in at that interval. I use the NGK IX Iridium (cheapest) from Advance auto. I don't buy plugs online anymore I got counterfeit ones from amazon twice, and ebay once.

 

[apollo18]

since it idles reeally well, does that mean spark plugs are def fine?

 

[KrisZ]

You’re not supposed to check or gap the plug, yet every service manual lists what the gap is supposed to be. So how do you know the gap is correct if you can’t even check it?

Oh the internet wisdom

 

[Invisible]

I didn’t have a gapping tool so didn’t care to check the gap

There's your problem. Even if the spark plugs are pre-gapped from the factory for your particular application, the gap can change while the spark plug is inside the box due to how it's handled. People drop these, they get tossed round in shipping, etc.

Watch this:



How long before you will address the problem and install them correctly?

 

[pbm]

I have 4 different gapping tools and all show different numbers on the same plugs.