Replaced spark plugs, car feels noticeably slower

[Conquest351]

Hey y'all. I recently replaced the spark plugs on my 2014 SHO I recently acquired just as a maintenance item. Car was running perfectly fine. I pulled out Autolite XP 5863 spark plugs and replaced them with Motorcraft SP-542 plugs. I gapped them at .026 as recommended by another member. The Autolites were anywhere between .030-.032 gap. I went out on a test drive and then drove the car 2 hrs to Austin, farted around all weekend and drive home. The car feels much softer I guess is the best way to put it. Not as harsh on acceleration, not as quick. It just feels slower. Whereas I would usually get to 120 in a flash, now it takes longer to reach even 110 on these deserted back roads in rural Texas. Is it just my imagination or are these plugs set up for a tuner and I'll see more of a reaction once I get my tune? I've done plugs many times before, not really a noob. I did check the plugs for cracks in the insulation, found none. I also replaced the boots on the ends of the coils as well. Am I imagining things or am I getting used to the car or what? LOL

Thanks in advance!!

 

[Lostneye]

Are you tuned if so with which tuner? SP534s are the recommended heat range for stock and some tuners. Some tuners do recommend the SP542s at varying gaps. 0.026 may to small for your setup/tune and not providing enough spark.

 

[SM105K]

Are you tuned if so with which tuner? SP534s are the recommended heat range for stock and some tuners. Some tuners do recommend the SP542s at varying gaps. 0.026 may to small for your setup/tune and not providing enough spark.

I agree. At least open the plug up to .030 and go from there.

 

[Conquest351]

Bone stock. No tuner yet. Will be getting a Gearhead tuner this week.

 

[Lostneye]

Bone stock. No tuner yet. Will be getting a Gearhead tuner this week.

Speak to Gearhead, I do believe the recommend the 542s so you might be good but I would guess the colder plug gapped to tight for the stock tune if your issue.

 

[SM105K]

Speak to Gearhead, I do believe the recommend the 542s so you might be good but I would guess the colder plug gapped to tight for the stock tune if your issue.

The more I learn, the more I see these cars do not like a small gap.

 

[Conquest351]

I will open them up to .030 after work and take a drive and see how that feels.

 

[SM105K]

Report back here if you could.

 

[Conquest351]

Or should I go a little larger, like .032?

 

[Conquest351]

Report back here if you could.

Absolutely will do

 

[SM105K]

Or should I go a little larger, like .032?

0.030 should be sufficient and should make a noticeable difference.

 

[Conquest351]

I have a 3Bar MAP, do I need to wait for the tune to install it or just go ahead and pop it in?

 

[Lostneye]

Or should I go a little larger, like .032?

Stock gap is .030 I wouldn't go larger.

I have a 3Bar MAP, do I need to wait for the tune to install it or just go ahead and pop it in?

You need a 3bar tune to run the sensor. It would be obvious by how bad the car runs if you did not.

 

[Conquest351]

Spoke to Gear Head. They said leave the gap alone as the tune will up the boost and reducing the gap would be advised at that point anyway. So I'll just leave it alone and get the tuner ordered Friday when I get paid.

 

[SM105K]

Spoke to Gear Head. They said leave the gap alone as the tune will up the boost and reducing the gap would be advised at that point anyway. So I'll just leave it alone and get the tuner ordered Friday when I get paid.

Cool, glad to hear Matt is taking care of you.