running a little funny after changing spark plugs

**godless-phoenix** · 02-16-2011, 01:18 PM

so over the weekend i changed my plugs and wires...i used ac delco iridiums (41-110) and msd wires...i was using ngk tr55's before...basically it seems like the car has lost a little power, it runs smoother and it doesnt back fire or miss anymore, witch is good... but it just feels less powerful than it did with the older ngk plugs that were in before (or am i just high)...i dont understand, because everythings tightened down and the wires are on there good...im getting a tune done friday so ill ask the mechanic doing the tune??? anyone ever have this problem?

just wanted to add that i wasnt expecting a power gain by putting in iridium plugs, but i wasnt expecting them to make the car run funny either...

**Too Fast** · 02-16-2011, 03:14 PM

Try cleaning your MAF. And making sure the plumbing is tight behind it.

**024mula** · 02-16-2011, 03:27 PM

Think you accidently broke a plug?

**jiveass** · 02-16-2011, 03:30 PM

make sure the passenger rear plug wire is on completely on both ends...i had this happen over the weekend....

**godless-phoenix** · 02-17-2011, 07:05 AM

ok checked everything, still runs like a turd...it even sounds less loud too

***SMWS6TA*** · 02-17-2011, 07:11 AM

I hope you didn't crack a plug while installing. Is it throwing any codes? If you really want to know if there's a difference throw the old ones back in and see.

Also, hate to say it but are the current plugs gaped correctly? Seen it to many times ppl never check the gap.

**godless-phoenix** · 02-17-2011, 09:05 AM

Originally Posted by SMWS6TA

I hope you didn't crack a plug while installing. Is it throwing any codes? If you really want to know if there's a difference throw the old ones back in and see.

Also, hate to say it but are the current plugs gaped correctly? Seen it to many times ppl never check the gap.

i talked to a mechanic this morning and he basically said the same thing, so im gonna try putting the old wires back on, cause i cant find witch wire it is exactly, but i think i remember maybe twisting one too much and maybe it f'd up the wire, i dunno, it seemed fine...they were ac delco iridiums, and they said they come pre-gapped at .040 and not to adjust the gap, i did check one plug, and it was .040, so i just assumed the rest were the same...i have a feeling it might just be a bad wire, im gonna let you know later after i replace them with the old ones... no codes, just doesnt run as good as it used too

***SMWS6TA*** · 02-17-2011, 09:49 AM

Gap is suppose to be .050, check the NGK and see what the gap is.

**Lunatikgixxer** · 02-17-2011, 10:10 AM

always check all ur gaps, dropping one on the concrete can change it. My next guess would be maybe one of your spark plug wires isnt on all the way, sometimes they can be pretty tricky.

**godless-phoenix** · 02-17-2011, 12:57 PM

when i did my ngk tr55's they were all gapped at .050 ran good with those, put the ac delco iridiums in gapped at .040 runs crappy to me... i just put the old plugs on, seems the same, might be the plug gap then...it says not to change the gap, i was just doing what i was told, so if i couldnt change the gap anyway, i didnt really feel the need to check all the plugs...i didnt drop any of them on the ground

so my question is, if the gap is supposed to be .050, then why do they come gapped at .040 and then they say not to change the gap, its really confusing. now i probably have to change all my plugs again! lame! grrrrrr!

**Lunatikgixxer** · 02-17-2011, 01:43 PM

Originally Posted by godless-phoenix

when i did my ngk tr55's they were all gapped at .050 ran good with those, put the ac delco iridiums in gapped at .040 runs crappy to me... i just put the old plugs on, seems the same, might be the plug gap then...it says not to change the gap, i was just doing what i was told, so if i couldnt change the gap anyway, i didnt really feel the need to check all the plugs...i didnt drop any of them on the ground

so my question is, if the gap is supposed to be .050, then why do they come gapped at .040 and then they say not to change the gap, its really confusing. now i probably have to change all my plugs again! lame! grrrrrr!

PITA huh? haha

**godless-phoenix** · 02-17-2011, 01:51 PM

Originally Posted by Lunatikgixxer

PITA huh? haha

just a bit ;P haha...im getting better at changing them. i did it in half the time (2 hours) than i did last time,witch took me 4 hours, haha...well, im getting a tune done tomorrow (cause im stuck in the diablo tune since someone stole it) so if its still running weird, ill ask him to just figure it out, ive checked it 3 times, my hands are tired, haha

**pajeff02** · 02-17-2011, 01:53 PM

Did you hear/feel the plug wires click once on your plugs and twice on your coils during installation?

**godless-phoenix** · 02-17-2011, 02:07 PM

yesh sir! i noticed my newer msd wires looked a little different than my old ones...my old ones the boot is straight, new ones angled...and the new ones had plastic inside around the coil part of the wire, the old ones did not have that...

**Lunatikgixxer** · 02-17-2011, 09:37 PM

this is really weird, like how bad is it running? huge difference or a minor difference only you would notice since you drive it everyday?

**godless-phoenix** · 02-20-2011, 03:21 PM

alright, to make a long story short... took all the spark plugs out and took a risk...i carefully gapped all the iridium plugs from .040 to .050...problem solved, runs like it should...kinda stupid they tell you not to gap them when you obviously do. live and you learn. atleast now i can do the plugs and wires on the LS1 in about an hour and a half from all the practice

**Too Fast** · 02-21-2011, 02:42 AM

I wonder if maybe a plug wire wasn't all the way on, and you fixed it when you gapped the plugs.

**pajeff02** · 02-21-2011, 08:25 AM

Originally Posted by Too Fast

I wonder if maybe a plug wire wasn't all the way on, and you fixed it when you gapped the plugs.

^^ Same. My understanding is that the Iridiums like a smaller gap -- I just installed .040" gapped platinum plugs in one of our vehicles. I think Cutlass posted a good article on the differences between the plug styles a while back and it did mention the reason for the smaller gap setting. I'll see if I can find it.