5000+ RPM misfire, *updated 9/12*

[Joe]

at a drift event tonight my car devloped a misfire above 5000, it sputters pops and kicks the tach around like crazy. its like a roaming rev limiter, moves up and down but will never allow me all the way to 7.

played with the timing, didnt help.

my neighbor has a S1 RB25 while mine is S2, do the CAS's interchange so i can troubleshoot without having to buy parts? (krayton i love you let me borrow it )

on the upside, i put coilovers on (Tein Super Drifts) and they are BADMOTHER****INGASS. cant wait to get onto a real racetrack at the end of the month, if the car is running haha.

[gawdzilla]

short answer, yes. if it looks the same on the outside, then use it. all it is is a hall effect sensor. as long as yours isnt the funky black one (see below), then it'll probably interchange. who knows, even if you have the funky black one it might work too.

long answer:

i'm looking at FAST now. what defines S1 and S2 (years)?

its showing 3 different part numbers....23731-02u11 for 94-97 (mitsubishi, the 3 diamond logo is in the middle. this is the only one i've ever seen in person and it is the same across all RB motors until the late years) 23731-08u00 for 93-97 (hitachi, i've never seen this one)23731-5L300 for 97+ (this one looks physically different... it is a black sensor w/ a smooth cover- i've seen it in photos on r34 gtrs)

[Joe]

i think S1 and S2 are seperated at 97. but dont quote me because ive only read it once.

[gawdzilla]

is your cam sensor the black smooth looking one? if not it will be interchangeable.

[Joe]

no it is not

its the standard silver ugly thing

[gawdzilla]

probably interchangeable w/ your friend's. the p/n is written on the CAS itself too btw.

[Joe]

ill have to give it a try tommrow, i hope it fixes the problem i hate these type of problems.

[eh?]

sounds more like a coil issue. But a SI and SII should be compatible. I've used a SI head with a SII CAS.

[Joe]

in my head i just cant picture 1 coil causing this problem. i mean theres 6 cylinders, eliminating 1 coil wouldnt cause a crazy hard misfire, it would cause a miss but nothing like this. ill definatley troubleshoot that if the CAS dosent pan out.

[eh?]

i doesn't need to be 1 coil, it can be more. skylines has loads of threads about coil misfires.

[Joe]

but more than 1 going out at once? damn that would be very odd.

nonetheless, its on my list of **** to check.

[eh?]

Nope it's very very common. As the rpm increases the coil cannot handle it and not fire or there are cracks in the casing causing spark leakage.

[Joe]

well damnit those are expensive and hard to get. it needs to be something easy to fix and cheap hahaha i have a track event in less than 3 weeks

[eh?]

check this outhttp://www.skylinesaustralia.c...46&hl=

[krayton]

i agree with eh?

your breaking my balls though. but yeah if it comes down to it you can test it.

but that was my first guess was something with coils when we were at the track.

look up ways we can test the coils. and man you had your cas way retarted retarted. i went about that much when i turned the boost up and tuned with the safc and i still got tons of break up. dont do that again

[240sxed]

Tried replacing spark plugs? sometimes your plugs are so fouled from running rich etc that all you need is a plug change. Well on SR's i found that people who stutter above 4500 need plug changes sometimes.

[Joe]

krayton the cas test would be last result, ill check the coilpacks first. and the timing was set fine when i got there. you and i agreed to change it a little and see if it changed the problem the problem remained, now my timing is messed up lol

240sxed im gonna check the plugs today probably.

[Joe]

just pulled coilpacks off, they all ohm out to the same specs, and i dont see any obvious cracks or problems

gonna clean em, coat em with that araldite crap and see if it helps.

[krayton]

damn you and series 2. but last time i had really fouled plugs driving cleaned them up.

but also it wasnt break up from them, it was just a rough/dieing idle

[Joe]

no **** damn series2, if it IS a coil its gonna cost double to fix.

[Joe]

plugs look normal a little lean (white, no detonation) but i guess thats kinda expected since the only driving on these plugs is WOT track driving.

pulled the CAS off and there was a loose metal sound comming from inside when shaking it. opened the cas up and a couple small pieces of metal fell out

reeeallllyyy sorry about the quality but all i have a ****ty camera phone

[eh?]

It wouldn't make sense that would cause misfiring only above 5000. I guess try another one before you buy one.

[Joe]

uh small pieces of metal comming out of my cas means it gets replaced wether it was the problem or not. thats NOT supposed to be in there.

and it makes sense to me. debris or a wobble in the shaft could definatley cause a bad signal going to the ECU. the ecu bases ignition off the signal from the CAS. the small pieces of metal look like a washer of some sort, a thin one maybe some kind of thrust washer.

[240sxed]

uh small pieces of metal comming out of my cas means it gets replaced wether it was the problem or not. thats NOT supposed to be in there.

and it makes sense to me. debris or a wobble in the shaft could definatley cause a bad signal going to the ECU. the ecu bases ignition off the signal from the CAS. the small pieces of metal look like a washer of some sort, a thin one maybe some kind of thrust washer.

Sounds right, but u think those little metal pieces are one tooth/or teeth? maybe it skips only 1 tooth every once in a while or something?

[Joe]

the teeth that go into the cam itself are fine, this is internal to the CAS

it looks like the shaft is pressed into the outer casing so i can only remove about 1/2 of the cas, there is still metal on the backing side that i cant get out and im assuming where it originated from.

[eh?]

Obviously it needs to be replaced. I ment as far as your misfire problem that may not be the cause.

[Joe]

with the troubleshooting ive done so far its the only problem ive found. so if this dosent fix it im in deep ****.

[eh?]

I have two cam angle sensors coming in. Do you have once sourced already?

[Joe]

not yet. as its a holiday none of my sources were at work/sober/alive? today so ill find out tommrow if any of my buddies shops have them lol

when are yours comming in? im in a serious time crunch at the moment. ive got 18 days to get the car track ready. still have a ton of work to do and this isnt helping any haha

[eh?]

I should get one sometime tis week.