Does Mis-fire Actually Damage Anything?

[illusiVe]

my search came up with lots of topics on how to remove, but not if its bad for engine/turbo etc.

my R34 GTT is on 10psi with stock turbo, just recently under heavy acceleration it seems to missfire asif traction control is on (which it isnt) and i get lovely pop pop pop pop noise (while accelerating) towards redline, happens occasionally not consistantly..

could this be the R&R i've heard so much about? but why havent I had this issue before today?....

[mad082]

rich and retard isn't a popping sound. it is just a dead stop in power. it sounds like you have ignition issues, like a dud coil or spark plug. this isn't that bad as it isn't really doing anything except not sparking. it would actually be cooling the cylinder that isn't firing.

[illusiVe]

ok, so more of something i can still drive with.. but nothing that needs imediate attention.. tis good cause i have no money

[mad082]

have you diagnosed as to what the problem is?

also if it is only under hard acceleration, just don't acellerate hard until it is fixed.

[r33_racer]

could be a slight leak somewhere in the piping.

[Haxorz]

I'd bet it's exactly what I had... check this thread.

[illusiVe]

i put boost to 11psi, doesnt happen anymore..

no farken idea.

it almost sounds like a rev limiter so it might pop every .3 seconds under the hard acceleration, then just stops.

power seems to die for the .3 seconds, or whatever, boost holds.

either way, problem gone for the moment.

[chrissso]

Hmm, I'd go to the dyno and get your fuel ratios checked.

Popping is most commonly because its too rich. Rich mixture is harder to ignite. Then the mixture is burnt after it has exited the cylinder giving a pop. Usually caused by the air flow metre detecting too much airflow, (usually from intake mods like fmic and pod). The EUC adds not just a littlle more fuel, but a lot more. Too much infact as it thinks the excess flow is a problem.

I regard to the issue going away after the boot rise...

I can't say for r34's, but with 33gtst's, it would seem that the fuel pump only supplies enough fuel for std boost.

Your poping might have gone on higher boost because your fuel pressure might be dropping, and themixture is coming back to lean, or at least closer to where it should be.

Anyway, there are 101 answers to this.

IMO minor popping, as long as it is a minor misfire is not going to cause imidiate problems. However, if it is running rich, and you don't do something about it, then you risk other issues like cat damage and washing the bores.

Best best, get it checked on the dyno and then talk to the tuner about a course of action. Most probably ECU, maybe a fuel pump.

Chriso

[Guest 40th-edition]

unburn fuel will damage the cat if it gets to much..

other wise miss shouldnt have any detrimental affects..

it will also use more fuel

[psybic]

Wow, I was JUST about to add about richness damaging the cat. Good point!

I have experienced an engine running way to rich and damaging the cat in a 3SGTE, which has the cat IN the DUMP PIPE! Stupid place I know, so more prone to getting damaged I guess... but yeah, amazing how much power you will be loosing if you are both running rich AND have a blocked cat.

I went from 62fwkws to 125 fwkws on that car with hi flow cat + retune.

Edited September 21, 2006 by psybic

[Nozila]

then you risk other issues like cat damage and washing the bores.

cat damage i undertstand, but 'washing' the bores? i didnt know this was possible. my understanding is that running rich only cause rediculous fuel consumption (blocked o2 sensor) and damaged/blocked cat.

[RB20_ZED]

unburn fuel will damage the cat if it gets to much..

other wise miss shouldnt have any detrimental affects..

it will also use more fuel

is damaging the cat really that bad a thing? wont it just start to become a "high-flow" cat?

[illusiVe]

last dyno showd AF was very rich, even when on stock...

[RB30-POWER]

is damaging the cat really that bad a thing? wont it just start to become a "high-flow" cat?

ahh, no...

it melts and causes a major restriction or blockage in the exhaust system, not what you want.

[Rolls]

i put boost to 11psi, doesnt happen anymore..

no farken idea.

it almost sounds like a rev limiter so it might pop every .3 seconds under the hard acceleration, then just stops.

power seems to die for the .3 seconds, or whatever, boost holds.

either way, problem gone for the moment.

Id say its a spark problem, weak coils possibly not causing a powerful enough spark. The higher boost level is blowing the spark out. Try gapping your plugs down (requires less energy for the spark) Also 11psi is as high as you want to boost the stock turbo. It wont last much longer above this level.

Its a very common problem, usually coil/sparkplug related. However it could be something else.

Read all about it here http://www.skylinesaustralia.com/forums/in...showtopic=32356

Edited September 22, 2006 by Rolls

[scags]

I had the same symptoms about a month ago with my R34 - misfirung under load at aroung 5krpm. Turned out to be the Fuel Pump. Replaced with bigger one (after a headache removing my Amplifiers to get to it) and walla - all fixed.

[illusiVe]

ahh, no...

it melts and causes a major restriction or blockage in the exhaust system, not what you want.

just keep melting it until its nolonger there

[RB20_ZED]

ahh, no...

it melts and causes a major restriction or blockage in the exhaust system, not what you want.

i guess ur assuming that when it melts u turn the car off and let it set... my guess is that the melted bits will be blown out the arse of the car.

[RB30-POWER]

what happens in reality, is the cat will usually break apart into pieces that are too large to go out the exhaust, but they block the outlet in the cat, (exhaust pressure pushes the loose bits to the outlet of the cat causing restriction) and your car doesn't make much boost/power due to the restriction and it can't melt further because the exhaust temps dont get high enough, because the vehicle isn't making any power.

the above has happened on almost all vehicles i have changed cats on, and they aren't all performance vehicles either.

[D-limo]

Remember a fault in the ignition (if its intermitant) will usually rear its ugly head when the car is under full operating temp...