Engine jittering while flooring it after installing Densos High performance spark plugs

tumtum

Registered Member
35
17
8
Genesis Model Type
Genesis G70
I just installed the new densos high performance spark plugs off the jb4 website so that I can install the JB4 chip. But after I installed it under full throttle my engine sort of jitters. I don't think it is the transmission either but who knows? I have the 3.3t. I don't know if it could be engine knock, misfire, or what? Did anyone else have this problem. Also I may have just messed up the installation of the plugs because I did it myself.
 

Toddasaurus

REEEEEEEEEEEEEEEE!!!!!
3,299
4,475
113
Genesis Model Type
Genesis G70
Did you end up gapping them at all? Any pics?

Make sure the coil packs are fully seated.

I doubt it's the tranny. My bet is on the plugs. There have been reports, both here and on the Stinger forum, of Denso's having some poor quality control. This might be what's causing that weird sensation you're getting at WOT. My assumption is that the plugs are misfiring at high RPM's.
 

tumtum

Registered Member
35
17
8
Genesis Model Type
Genesis G70
Yea I gapped then to .022 and no I don't not have any pics unfortunately. A buddy told me that it might be bad gas, but I also didn't tell him I changed the spark plugs. I might wait a few days to see if my car will get used to them or not, should I just buy new plugs and have a shop do install them correctly?
Did you end up gapping them at all? Any pics?

Make sure the coil packs are fully seated.

I doubt it's the tranny. My bet is on the plugs. There have been reports, both here and on the Stinger forum, of Denso's having some poor quality control. This might be what's causing that weird sensation you're getting at WOT. My assumption is that the plugs are misfiring at high RPM's.
 

Toddasaurus

REEEEEEEEEEEEEEEE!!!!!
3,299
4,475
113
Genesis Model Type
Genesis G70
Yea I gapped then to .022 and no I don't not have any pics unfortunately. A buddy told me that it might be bad gas, but I also didn't tell him I changed the spark plugs. I might wait a few days to see if my car will get used to them or not, should I just buy new plugs and have a shop do install them correctly?

Double check your coil packs, also I think it would be a good idea to pull the plugs and inspect them, double check your gap, and make sure the center and ground electrodes look good. There is a chance that you've just got plugs that happened to be crappy quality. Usually Denso's work great, but you're not the first person to have problems with them despite doing things correctly.

Personally, I prefer re-gapped OEM plugs. Been running mine for approx 3,000 miles, with upgrades, and they've been perfect.
 
Looking to update and upgrade your Genesis luxury sport automobile? Look no further than right here in our own forum store - where orders are shipped immediately!

socrbob

Enjoying the sharing of information.
SUSTAINING MEMBER
83
23
8
Missouri
Thanks for your reply, just seemed a little too tight to me. Apparently the jb4 requires the smaller gap. Have you gotten rid of your problem, if so how?
 

tumtum

Registered Member
35
17
8
Genesis Model Type
Genesis G70
Thanks for your reply, just seemed a little too tight to me. Apparently the jb4 requires the smaller gap. Have you gotten rid of your problem, if so how?
No not yet I'm going to wait a few more days and if the problems persist I am going to go to a shop and ask them to check my work if I did everything right, but I'll keep you updated.
 

tumtum

Registered Member
35
17
8
Genesis Model Type
Genesis G70
Double check your coil packs, also I think it would be a good idea to pull the plugs and inspect them, double check your gap, and make sure the center and ground electrodes look good. There is a chance that you've just got plugs that happened to be crappy quality. Usually Denso's work great, but you're not the first person to have problems with them despite doing things correctly.

Personally, I prefer re-gapped OEM plugs. Been running mine for approx 3,000 miles, with upgrades, and they've been perfect.
Did you regap the OEM plugs to .022?
 

Toddasaurus

REEEEEEEEEEEEEEEE!!!!!
3,299
4,475
113
Genesis Model Type
Genesis G70

tumtum

Registered Member
35
17
8
Genesis Model Type
Genesis G70
Also I may have figured out my problem. I went to the mechanic shop and they said I had low counts of misfire in cylinder 2, so it probably happens under WOT. I order a new plug and I'll replace it and see what happens. Also when you anyone replaced their sparkplugs did their gas mileage go down?
Ok thanks, what did you base the .026 off of.
 

Toddasaurus

REEEEEEEEEEEEEEEE!!!!!
3,299
4,475
113
Genesis Model Type
Genesis G70
I can't remember how I got 0.026", but it seems to be working pretty good. Haha.

Unsure about my gas mileage. I haven't driven much highway recently so I can't really compare just yet..
 

tumtum

Registered Member
35
17
8
Genesis Model Type
Genesis G70
I just installed the new densos high performance spark plugs off the jb4 website so that I can install the JB4 chip. But after I installed it under full throttle my engine sort of jitters. I don't think it is the transmission either but who knows? I have the 3.3t. I don't know if it could be engine knock, misfire, or what? Did anyone else have this problem. Also I may have just messed up the installation of the plugs because I did it myself.
Hey guys I figured out the problem. One of my spark plugs were cracked. I probably cracked it in the installation because I dont know crap lol. But I installed a new plug and it seem to fix the problem. However I forgot to check if there was ceramic left at the bottom of the cylinder... o well we will see what happens 🤷‍♂️🤷‍♂️
 

Attachments

  • 20191122_132103.jpg
    20191122_132103.jpg
    112.1 KB · Views: 35

Toddasaurus

REEEEEEEEEEEEEEEE!!!!!
3,299
4,475
113
Genesis Model Type
Genesis G70
Oh dang! Yup, that's cracked lol.

If the engine is running smoothly now then I think you're all set. If there was ceramic in the cylinder then you would've noticed something weird upon startup.

I'm glad you got it taken care of!!
 

tumtum

Registered Member
35
17
8
Genesis Model Type
Genesis G70
Glad you were able to fix @tumtum. (y):cool: It's no fun taking the intake off to get to the passenger side plugs.
Funny thing tho, we couldn't take the intake manifold off completely, because the clamps attached to the intake had bolts I've never seen before so we managed to take out the sparkplugs with out taking off the intake. It was much harder tho and a lot slower. I'll provide a picture of the bolts I'm talking about later.
 

Wyo_Cowboy

Registered Member
34
36
18
Clermont, FL
Genesis Model Type
Genesis G70
Funny thing tho, we couldn't take the intake manifold off completely, because the clamps attached to the intake had bolts I've never seen before so we managed to take out the sparkplugs with out taking off the intake. It was much harder tho and a lot slower. I'll provide a picture of the bolts I'm talking about later.
Those are just caps over the clamp screws on throttle body. Just pop off.
 

Attachments

  • IMG_20191127_163545.jpg
    IMG_20191127_163545.jpg
    215.8 KB · Views: 24
Top