Author Topic: jdm gc8 MISFIRE! like no other? (Read 11770 times)

S Q U I N Y · « **on:** June 22, 2009, 01:30:54 pm »

Alright... so I've got a jdm rhd 1993 GC8
and with my bright idea i went ahead and changed out
my spark plugs the other day.
the old: Denso VK20Y IRIDIUM Tough's
the new: NGK IRIDIUM's (02 subaru impreza wrx)

on the first start up as i was getting out of the garage and slight revs at the same time
there was this really loud POP! from the driver's side (right side) after that everything was ok
but after the first start up and when i took the car out for a spin (hopeing it was a one time thing)
i noticed the car would run really good under 4000rpm
but once i reach 4000rpm+ the car starts chugging and it seems like it's misfiring.

anyone have any suggestions?
I haven't replaced my coils yet. would this possibly help my situation?

PLEASE HELP!!!!! thanks in advanced to everyone!

SubieRoo · « **Reply #1 on:** June 22, 2009, 01:33:30 pm »

Did you look at your coils when you were changing your spark plugs? Id say it sounds like your coil packs, I have the same spark plugs as you.. unless one of the iridium tips is broken.

silent · « **Reply #2 on:** June 22, 2009, 04:26:26 pm »

Can we sticky one of these threads with the answer? We see these threads on a weekly basis.

Check your plug gap and if that fails, its almost guaranteed your coil packs are toast.

SubieRoo · « **Reply #3 on:** June 22, 2009, 04:30:06 pm »

The gap on the NGK's is .03, its set, you cant gap it anymore or any less. It looks like it would be the coilpacks.

S Q U I N Y · « **Reply #4 on:** June 22, 2009, 08:29:31 pm »

well i checked my coilpacks and there doesn't seem to be any damage to the naked eye
i mean they actually look pretty new.
i looked inside at the contacts and they look pretty new also.
i'm gonna try and put my old ones back in after a clean and see how that works

but would it be a good idea to replace my coilpacks anyway even if the car runs fine again on my old
spark plugs?

SubieRoo · « **Reply #5 on:** June 22, 2009, 09:28:11 pm »

It doesnt hurt man, and preventative maintenance is a good idea. That would be considered preventative maintenance

S Q U I N Y · « **Reply #6 on:** June 22, 2009, 11:43:33 pm »

haha I totally agree if only my money tree wouldn't reject me so much

SubieRoo · « **Reply #7 on:** June 23, 2009, 12:17:07 am »

You just have to search, you'll get a good deal, I found and did mine for a very reasonable price.

S Q U I N Y · « **Reply #8 on:** June 23, 2009, 12:32:16 am »

how much did you get yours done if you don't mind me asking?
(you could pm me that answer lol)

sniper512 · « **Reply #9 on:** June 23, 2009, 09:42:29 am »

When you checked your coils did you pull the boot off of the coil and check the hard plastic part of the coil that houses the contact spring? Also your gap should be no more than .028 for these cars. Once you get the car to run good with no misfires you will probably start to notice that the car feels like it is pulling timing up high above 4500rpm. This is also normal on our itshay gas and a retune is needed. If I can't get a shift fork for my tranny in the next week I will be selling my Z4 ECU tuned by Rob on NASIOC. I am gonna park the car for the year and go standalone to do my 2.5 block for next year

.

SubieRoo · « **Reply #10 on:** June 23, 2009, 11:52:14 am »

My gap is .03 and I have no problems whatsoever. NGK Iridiums are pregapped, and you cant change that, bought mine for an 02-04WRX.

And I did pm you.

sniper512 · « **Reply #11 on:** June 23, 2009, 11:56:19 am »

You PM'ed me?

Trust me once you get up around 15psi .028 is a much happier place

S Q U I N Y · « **Reply #12 on:** June 23, 2009, 12:24:16 pm »

Thanks guys
and i'll give the new coilpacks a try
maybe sti coilpacks will do my scooby good
and i want to say i did pull the boot off to check but that's a negative lol
i just hope it is the coilpacks cause the sti coilpacks are pretty expensive it's like
90 each +shipping

and he meant he pm'd me lol

farva · « **Reply #13 on:** June 23, 2009, 01:18:34 pm »

I found 02 wrx coil packs on NASIOC for 120 shipped for all four, and you wont be able to see if a coil pack is shot unless you take off the boot. I thought mine were fine till I pulled the boot off and one was broken into 3-4 chunks. Pull the coil pack right by the turbo that will be the worst one.
http://forums.nasioc.com/forums/showthread.php?t=1783869 there you go all four for 80

D-cal · « **Reply #14 on:** June 23, 2009, 01:25:48 pm »

Has anybody actually investigated why these coil packs \"go bad\"? I\'m just curious. Cold solder joint? Broken winding? Spring loses tension? Someone with the know-how dissect a couple.

sniper512 · « **Reply #15 on:** June 23, 2009, 01:34:39 pm »

I did. The plastic case actually falls apart due to I am thinking heat cycles and extremely hot temps. Once they have cracked and failed the coil will actually arch from the coil to the head makes for a nice light show at night if your wondering. This is very common on the older JDM Subies. I have never come across one that didn't need the coils replaced. Most motors that come over to swap have this problem as well or will.

SubieRoo · « **Reply #16 on:** June 23, 2009, 05:20:18 pm »

Id agree with Sniper. Heat cycles on these packs will do the job.
Mine wasnt the plastic parts of the plugs, but rather the boots funny enough.

S Q U I N Y · « **Reply #17 on:** June 23, 2009, 11:13:08 pm »

no but i sure will take them apart once i get my new ones
i'm REALLY curious of why and what's going on with them too!!!
i mean it couldn't just be from age and wear and tear
(actually to think this might be a problem? i think....?)

ok nvm i never even realized this got to a second page...lol
but thanks "farva" for the link i just hope he hasn't sold them yet
and thanks to everyone else too i'm learning so much!

S Q U I N Y · « **Reply #18 on:** June 27, 2009, 12:29:32 am »

k so i ordered a set of coilpacks from a guy on nasioc in the states
they should be at my doorstep around the end of the first week of july

just keeping anyone that cares posted haha

Thanks again to everyone that helped me out and contributed their
"know how" and tips

sniper512 · « **Reply #19 on:** June 27, 2009, 08:55:10 am »

Nice I am helping a friend do the swap in a few mins lol its easy just don't wire i wrong;)

SubieRoo · « **Reply #20 on:** June 27, 2009, 09:52:59 am »

Quote from: S Q U I N Y on June 27, 2009, 12:29:32 am

k so i ordered a set of coilpacks from a guy on nasioc in the states
they should be at my doorstep around the end of the first week of july

just keeping anyone that cares posted haha

Thanks again to everyone that helped me out and contributed their
"know how" and tips

Cool man, I think you'll be happy. Which coilpacks did you get, did they come with the boots?

S Q U I N Y · « **Reply #21 on:** June 27, 2009, 04:33:37 pm »

lol well i didn't get them yet but in the pictures they look like they come with the boot
it's the link that farva sent me in his post.

i just hope there's nothing wrong with them.

haha and i'm gonna follow that write up on nasioc for the coilpack conversion.
hopefully i'm not as bad with following instructions as i was before...

SubieRoo · « **Reply #22 on:** June 27, 2009, 09:44:37 pm »

Awesome, Im sure they'll work fine. The instructions on NASIOC are awesome, I followed them to a T and it went well. When you get them, give me a shout if you want an extra hand.

S Q U I N Y · « **Reply #23 on:** June 27, 2009, 11:10:06 pm »

haha thanks for the offer dude
i might definately have to take you up on that offer

S Q U I N Y · « **Reply #24 on:** June 27, 2009, 11:52:03 pm »

HOLY ISHTAY!!!!!!!!!!!!!
k so i have to admit i was pretty lazy lately and didn't get around
to buying a spark plug gapper but thank god i got around to it today!
i just checked my NGK iridiums and so much for being pregapped!
they were freakin gapped to .040!!!!!
yes these were the BKR6EIX-11's and i know everyone said they were supposed to be
.028.... yeah... NOT SO MUCH!

NO WONDER I HAD A MISFIRE!

The reason to why i bought a gapper today and stopped being a cheap little ishtay:
i noticed after installing my old plugs the car ran a lot better.
i'm not saying it's like a new car because my coilpacks could also be an accessory to the crime
(they haven't been replaced yet) and like i said before the misfire seems to return after driving
the car for a while. so i was curious why my new plugs were gapped to due to the numerous measurements
that people told me about. to my surprise it wasn't anything anyone told me about. hopefully it's just the two
packages that i bought...

Thanks again everyone for the help and tips

Author Topic: jdm gc8 MISFIRE! like no other? (Read 11770 times)

D-cal