Car misfires in cylinder 2 at 100mph.

[tyler2687]

This is not my car I’m talking about but asking for a friend. He has a 2017 fiesta st he just bought with 70k miles . and as far as I know it’s tuned on93, has a 2jr intake setup , a guardian angel map setup, a upgraded inter cooler , borla exhaust ,and miscellaneous cosmetic parts . Car runs fine and pulls 23.4 psi at peak boost. After 100mph every time the check engine light comes on for a misfire in cylinder 2 . We changed out for new spark plugs and coil packs . Any ideas ?

 

[Capri to ST]

Keep it to 99?

Seriously, check the gap on the spark plugs. Also you might try switching another coil onto cylinder 2 as a way of double checking things?

 

[tyler2687]

It has a brand new set of ngk ruthenium’s and duralast coil packs that he bought so they should be good?

 

[Mikey456]

Have you noticed any coolant leak?

 

[tyler2687]

Have you noticed any coolant leak?

I don’t think

 

[FiestaSTdude]

It has a brand new set of ngk ruthenium’s and duralast coil packs that he bought so they should be good?

Like @Capri to ST said, I'd try switching the plugs and coils to see if the problem cylinder changes. Also even if the spark plugs claim to be gapped a certain amount, I'd still double check them to confirm that they're correct.

 

[Sam4]

and perhaps that 'dial the spark plug' thingy - orient the gap/spark into the fuel stream instead of possibly blocked by the ground electrode.

It's not the physics textbook related to the Bilstein B6/8 discussion, but there's truth to it at 100mph. Everything makes a difference there... (amazing discussion on those shocks/suspension in general)

 

[NATYPE]

Like @Capri to ST said, I'd try switching the plugs and coils to see if the problem cylinder changes. Also even if the spark plugs claim to be gapped a certain amount, I'd still double check them to confirm that they're correct.

Seconding to double-check the plug gaps. Pre-gapped sets I've bought have varied wildly and been inconsistent even within the 4 purchased together. Whoosh has a gaping tool and feeler gauge set for sale as of recently.

 

[tyler2687]

Checked all the gaps they were good just had a bad coil pack! Thank you guys for your help my buddy really appreciates it!! It was just so odd at only 100 mph it would misfire 🤷‍♂️

 

[esp_martin]

"Checked all the gaps they were good just had a bad coil pack! Thank you guys for your help my buddy really appreciates it!! It was just so odd at only 100 mph in Mexico it would misfire 🤷‍♂️"


fixed that for you.

 

[tyler2687]

"Checked all the gaps they were good just had a bad coil pack! Thank you guys for your help my buddy really appreciates it!! It was just so odd at only 100 mph in Mexico it would misfire 🤷‍♂️"


fixed that for you.

my apologies I forgot to inform the people that I am friends with border patrol and take weekly trips to mexico 😈

 

[FJ16]

Ah yes, Pennsylvania TX... right near the border.

 

[gtx3076]

Ruthenium plugs usually do not perform efficiently under extreme conditions like an engine running at high speeds or carrying heavy loads.

https://rxmechanic.com/ruthenium-spark-plugs/

I'm on stock plugs. My step colders were fouling up on E30.

 

[M-Sport fan]

^^^That link article seems VERY self-contradictory in parts.

Also, they do NOT define "high engine speeds" at all.

Depending on engine design (valvetrain, bore vs. stroke dimensions, etc.) the power band's upper peak could be maxxed-out at anything from 5500 revs to 9000+ revs for a street car, so even more confusion yet.

 

[gtx3076]

^^^That link article seems VERY self-contradictory in parts.

Also, they do NOT define "high engine speeds" at all.

Depending on engine design (valvetrain, bore vs. stroke dimensions, etc.) the power band's upper peak could be maxxed-out at anything from 5500 revs to 9000+ revs for a street car, so even more confusion yet.

I think some of these spark plug designs are gimmicky, but Tune+ has found some benefits depending on the application.

https://www.facebook.com/adamtuned/posts/1008226939606328

View: https://m.facebook.com/adamtuned/posts/1008226939606328