DzaztrBUSE

I changed all spark plugs on my GS400. I used the NGK Iridiums. For some odd reason my car is now misfiring. I feel a small stutter or pop outta my exhaust and a bump inside the car every few seconds at idle. What would this be from. I checked the gaps on the spark plugs and they were just fine. Someone help!!! Its annoying.

corkycal

iTrader: (8)

this may sound weird, did you get the right plugs? this shouldn't be happening if you installed the right plugs.

can you take it back to your mechanic?

DzaztrBUSE

Uhmmm, yeah...about that. I did them myself. I've replaced spark plugs before. I checked with NGK and have the part number right. I know NGK offers two different Iridiums for the car with one being the supposed "oem reaplcement". I didnt get that one i got the other iridium. have no clue what it could be.

corkycal

iTrader: (8)

this should be the ngk part number for the v8, BKR6EIX-11 / 3764. this should be the oem replacement.

if you're using these and it's still misfiring, hmm spark plugs wires?

santigs400

I think one of your ignition coil is bad. Did you install those plugs yourself? One more thing, check all the harnesses that plug into the coils (8 of them) and see if they are plugged in tight.
I've just done mine without any problem.

AZDesertGS

iTrader: (4)

You shouldn't gap at all....they should just be installed as is. So hopefully when you were checking the gaps...you didnt jack up the tips. They are very sensitive. Good Luck

DzaztrBUSE

You're correct. The gaps were where they needed to be cuz I checked just to be safe.

santigs400

The correct NGK plug number should be IFR6T11 for V8 2000 GS400.

DzaztrBUSE

NGK states that as the OEM replacement. It has two different option for the iridium series in which i got the latter.

Chpsk8

Sure the firing order is correct? One two wire mixup and you have issues.

joshoowa

iTrader: (1)

could be a coilpack gone bad or loose, i had a bad misfiring problem untill i tighten down all the coilpacks

DzaztrBUSE

Didnt get the chance to do it this morning. Didnt drive so at least I dont have to worry about burning my hands when I get under there. I think Im just going to re-do it and see if the problem still persists.

gserep1

You know,
I am having the same issue with my 99 GS4. The miss is intermittent, which makes me suspect a coil pack. But which one? The miss is very minor, but still noticeable. I am sure it affects gas mileage, which is not as good as my first 99 GS4, and doesn't have the SNAP the old one did. I changed sparkplugs, cleaned throttle body, checked all vacuum lines, and still there is just SOMETHING that just doesn't feel right. When I had my smog check done here in California, it passed, but the numbers were a little higher than they should have been, but there is no check engine light.

Other than going to the dealership for a scope, what else can be done? A coil pack is pretty expensive isn't it? I need all 8 of them to be sure. The car only has 112, 000 miles, so the coils should last longer than that shouldn't they? I get that little pop, pop, pop on part throttle acceleration while sitting still, and it is noticeable at the back of the car if you stand behind it.

My last resort is to wait until nearly dark, remove the top cover, idle the engine, and put a slight amount of water mist on each coil pack and see if I see sparks or something. Just a thought.

Thanks

santigs400

gserep1,
Why don't you just buy one new coil pack? I think it costs around $80.00 at the dealer or online.
I suggest that you install the new coil pack on the first cylinder and move the next one if the problem still existed. I think it's the cheapest way to diagnose the problem.

lexmenow

Took me a long time to change mine. I am not a mechanic. Did you put that conducter cream on top of the plugs before install?