more new plugs!!

[lenny]

a new set of ngk plugs in my 1.6sx lanos every 50 miles due to sudden misfire and lack of power. 3 sets in 2 weeks. any ideas please

[PrecisionBoost]

Plug eating Lanos eh?

Sounds like you have some nasty detonation happening here.

My first guess is that something is off with the timing of the ignition.

Given it's a distributorless system It could be some problem with the cam or crankshaft sensor.

Hmmm.... alternatively if your timing belt jumped a notch that would also cause the timing to be off ( plus it would run like crap )

I'm not sure if one notch is enough to make the pistons slap the valves but your car probably wouldn't run if the valves had been hit.

I was just talking here with Tom (360 Dynamics) and he was saying that some other posibilities are a vacume leak, wrong plugs (wrong heat range), O2 sensor problem, bad fuel pressure (could be a clogged fuel filter)

Do you done any modifications to the car?

Does the car run good and then all of a sudden misfire??

Does it have power once you replace the plugs?

Can you take a picture of the damaged spark plugs??

Does it happen on just one cylinder or all of them?

We need more info in order to help you out.

[lenny]

as soon as new plugs fitted it drives fine. it suddenly goes down on one plug and then it feels like it goes down on two. i have tried ngk and denso plugs . im sure last time i replaced them one plug was really black and coked up, i tried cleaning them but it made no difference i had to put new ones in. tommorrow i am replacing them again but i will do one at a time to see which ones had gone down. thanks for your help i will post my findings tommorrow. lenny... ...p.s i would take it to a garage but none want to take the job on .

[woo]

its not always wise to run the stongest spark plugs you can but. A common misconseption is that cars need the biggest spark available but the higher your compression, the less spark is needed or you will foul your plugs. Back off to a less powerfull plug and you should be fine../

[subachad]

What are you gapping the plugs to?

What do they look like? Have you compared that to a spark plug guide picture? That should tell you exactly what's going on. Can you post a pic of your bad plugs?

Chad
www.uniquemotorsports.com

[lenny]

i have been putting the plugs in as they come out of the box , the ngk book says they a preset at the right gap.i am now thinking it a overfuelling problem. ive purchased a compression tester and i will check this before i put yet another set of plugs and look further into a fuelling fault. also i do not get a check engine light come on when it misfires... sorry i dont know how to send photos through the internet yet, its taken me nearly 20 minutes to write this paragraph out..back in touch soon hopefully with more info..thanks for all advice.lenny

[woo]

i think one of the simplest things to do is ask the shop assistant what plugs will suit your car best. If everything is stock, i would lean towards everything being the plugs fault, not the engine managements fault

[lenny]

took plugs out today ,did compression test, cylinders 1 and 2 read 175, 3 reads 150, and 4 160. i needed to replace plugs on 3 and 4 to make the car run properly again . plugs 3 and 4 were black and wet. have done 40 miles today problem not reoccured yet but expecting it at any time. i think its time to get rid of the car . lenny

[jaejae b. pasco]

am new here, guys.... but i had similar prob like that last year. my stock ignition cable (mine's a 98 Cielo GLE) got pretty messed up for reasons i didn't know. my mechanic said there was a "backfire" or something -- figured it was a current backflow, i supposed. i changed my ignition cables/wires (silicon), all of 4 of them. didn't have any prob since. still using NGK type R....

[PrecisionBoost]

That's a good point.... it could be ignition problems.

Each cylinder fires twice per revolution...once at the bottom of the compresion/power stroke....and once during the exhaust/intake stroke...normally this isn't a problem due to the fact that there is no air or fuel left in the cylinder during the exhaust/intake stroke.

But let say one plug doesn't fire for a couple of cycles and then you go over a bump and it fires during the exhaust stroke the unburned fuel would make a nice boom as it ignites and goes out the open exhaust port.

So perhaps you should pull out your plugs one at a time and check to see if they are firing correctly.

I'd guess that if they weren't firing correctly it's very likely that it's the spark plug wires.

I say this because your problems were on 3 & 4 and the firing pairs are 2/3 and 1/4

So if 1 & 2 are getting spark from the coil then 3 & 4 would as well (which rules out a bad ignition coil )

[lenny]

good thinking.. i will try a new set of leads this weekend . . i understand what could make a plug go black or wet but what actually causes the plug to completely burn out. i am only replacing 2 plugs at a time now so we are half way there..cheers lenny