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what are the symptoms of bad/failing coil pack?

I am having this weird problem where the car feels like it is underpowered under the light/heavy load. intake still sounds befy. i think it is a sparking issue, what do you think could be the cause of it? BTW it is nb8a with aroun 110k on the clock...

Leads and spark plugs are the first port of call, how old are they?

leads are around 8 months old, and plugs are around 20-30 000 kms old, but they are the iridium ones and i ve been informed they last around 80 000 kays?? .. i will check the plugs tomorrow...

Change your plugs...

Iridiums blow

Now I know why you were interested in my new coil packs

Maybe the ECU just needs a bit of a tune-up?
fuel-filter a bit dirty? air filter a bit dirty?
If changing to different plugs as per ampz's suggestion don't work then change/clean other little, serviceable parts, and see if it makes a difference

1red, i have stock ecu, and simona cai with the shield i dont think there is a problem with the brething and i ve checked for the vacuum leaks...

what i can guess is eaither spark plugs or coil packs... i have changed my fuel filter about 6-8 months ago too...

if anyone know could failure to fuel pump cause similar symptoms?

just an update on this, i have changed the plugs and checked the coil pack by using a spare spark plug and it looks like they all had spark... took the car to jason at top tune in north sydney and he said its most probably CAS, and he changed cam angle sensor... now car is not as bad, but the problem is still there... when i am starting it, if i give too much gas, it misses... and under light/heavy load when i push the accelerator down, it stumbles around 3-5k rews... it feels like something is pulling the car from back and not letting go then when i take my foot off a little then it feels ok... very weird.. i think it is fuel related... any ideas anyone??

thanks....

It will be hard to work it out accurately without driving it, but I’ll try and narrow it down a little for you.

From description alone it sounds more fuel related than ignition, manly because its more throttle caused rather than RPM. (ignition issues often also have a lot of missing or flat spotting)

This is what may be happening, with more throttle you have more air, but may not be supplying enough fuel to match increase in air,
If its close to working mixtures, then it may just stumble with no flat spot, but if the fuelling really cant keep up, then it can cause flat spotting.

If so it could be any 1 of a number of Fuelling related problems, (More likely)- MAF sensor, inlet Air temp sensor, Fuel Pump, Fuel Filter,
(could also be) Oxygen Sensor, injectors , Water temp sensor,
We can rule a few out, but to be totally accurate it should be done with someone driving or testing it, as some of the above can give other symptoms, or be better or worse depending on RPM, throttle, engine temp etc.

Did the guy at top tune connect diagnostics, to read fault codes etc, if not he should have. It may not always show all faults, but it’s the best way to start, if something comes up its likely the problem.
Without doing that I can’t see why he concluded the CAS was faulty, but ask him as he may have seen another reason for it.

Also is there any hesitation-flat spotting, along with the stumble?

thanks for the advices rotary,

i have taken the car back to jason today and we took it for a drive, he reckons it is a timing issue... he will change the crank angle sensor today and take it for a spin to see if it fixes the problem... told him to check afm too... he has put the car on computer, but it does not give out any errors...he has taken the timing belt out and checked the crank, no problems with that either.... will post when he finds out what the problem is.

Let us know how you go,

Hopefully he sorts it out swiftly for you, maybe he can hear something in idle or rev up, thats directing him toward a timing or mechanical issue, his judgement should be far better than mine not having seen it, So i wouldn't rule anything out as yet.
Cheers, Matt.

well just called him, he has checked all the sensors and opened up the crank to see if there is any problems, chekced the timing belt and no problems.... i have been telling him that i am a bit suss of the AFM and he didnt think it was.. but now he told me that he will change the afm tomorrow and see how it goes...

oh well if there is nothing wrong from engine side, it probably is the fuel pump... damn it... oh well i wonder if it will cost me my left arm tomorrow...

will let you guys know definitely...

This is Concerning if you have to pay for His trial and error, as you may still not find the problem after changing everything.
Could always be a bad wire or conection, or worst case even the ECU can be faulty.

Im not sure of your agreement, but consider taking it to Mania, i'm guessing any part they trial and error with would be ones they have spare, and if wrong they would just put yours back on and try another.

It is a complicated matter so I wouldn't put down Top Tunes effort, but it might be worth it to give Mania a buzz and ask if they would do it like that.
Although there may be a large labour charge anyway, so it all depends on what your current arrangement is.

He may work it out very soon anyway, because he has had good time with it

Good Luck,
Matt

problem ended up being the fuel pump playing up... funny coz fuel pumps usually just work or not, this one was just being weird, and the symptoms were as if it was timing or sensor related...

i have to give credit to jason at ttauto, he is a real car enhusiast and loves what he does...i would recommend his service, honesty and reliability any day...