more stuttering/hesitation

[dickie]

i reported some trouble with my car sputtering/misfiring during accel under load and in neutral some months back. i had my friend ride in the car and he said it was either the spark plugs or the coils, so i replaced the plugs and all was fine...

until now. the problem returned but the plugs are showing no telltales they are at fault. i want to say its probably the coils... i replaced the plugs in opposite order from the cylinders i removed them and the problem is still occurring and from what i can feel hasn't followed the plugs.

i dont want to drop $50-$100 for another coilpack that might just crap out too unless i know for a fact that is the heart of the issue. anyone have an extra set i can borrow to troubleshoot? thanks.

[Titus]

Did you replace the plug WIRES?

[MadMonkey]

Did you replace the plug WIRES?

+1. I had stuttering problems at one point and changing the wires fixed it.

[creek]

NGK blues and a bottle of Techron.

[dickie]

they were brand new ngk when i bought the car but i swapped them with another set just to test and it didnt fix anything.

[POS Racing]

What year is the car?

How did the plugs look when you moved them around?

Take a minute and fill out your profile - http://forums.dfwmiata.com/member.php?u=877

[dickie]

the plugs had showed nothing out of the ordinary according to NGK's site, just normal wear and they looked like they should still be functioning correctly when comparing them to the new plugs.

i replaced them again anyway and sure enough the stuttering is gone again. but it will be back soon and i want to know what is causing it.

[channelmaniac]

The coil packs are wired up on the cars to give a spark on two of the plugs at the same time. This causes the spark plug to get 2 sparks per 4 stroke cycle, effectively halving their expected life.

[dickie]

but that wouldnt account for the plugs showing very little wear compared to brand new ones. the only difference was slight whitish brown discoloration indicating normal function.

???

[dickie]

starting to do it again, new plugs are a week old. pulled them, still look out-of-the-box condition.

[channelmaniac]

If you've replaced the plugs and wires... next thing to do is to check the plugs on the coil packs for corrosion... then clean and remount the ground wires that are down under the master cylinder/brake booster.

Beyond that you are into wiring harness, ECU, and CAS issues. CAS being the far more likely of the 3.

Does it do it when the car is hot? Cold?

RJ

[dickie]

it does it regardless of temp, has more to do with getting on the throttle. a quick stab or firm push on the pedal causes it to sputter until it hits about 3k rpm, misfiring on at least 1 cylinder.

if i gently push the pedal down it does it about 1/10 times. doesnt matter if im in gear and driving or from idle in neutral.

i replaced all my grounds when this first popped up and they still look good. i was hoping it would be something simple, sounds like its getting into the advanced.