AsleepAltima

shit is so annoying. stuttering at wot in the 1st three gears. reinforced the coil pack grounds, checked coil pack resistance - .7 across the board, grounded the head, checked fuel pressure - 38ish w/o vacuum, checked gaps - didnt matter if it was .022 or .028.

new build sr - s13 black top
87mm pistons
cosworth 1.1 head gasket
arp head studs
j30 maf
jwt ecu
gt2871
bc stage 2 cams
740cc injectors
cant think of anything else that should matter, for specs


http://www.youtube.com/my_videos_edi...id=Bmuek3r0KDE

Edwin562

Check if maf is good?

future

You chEck everything but the maf, nice one

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AsleepAltima

maybe i forgot to put that down? think of that? nice one.

i checked the maf, tried grounding it too and checked for voltage - both good.
also, tps is set to .45 and idle is perfect.

chetacheese

What kind of fpr are you running? And is it adjustable. If so, is it adjusted?

Is it a chipped ecu? Was it dyno tuned?

More info can help us help you eliminate some possibilities.

ultimateirving

How about Boost leak, When was the last time you pressure tested the entire system? Also BOV leaking at boost can cause horrible shuttering

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JDMRIDDAZ

the coilpack could still be bad even if resistance checks out
use a spark light...
this hasppened to me,,,
fpr should be 3bar
41-43 psi

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KiLLeR2001

Could very well be a bad coilpack if it happens around 4000 to 5000 rpms. Also does it matter if the engine is cold or at operating temp?

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AsleepAltima

im running an aeromotive fpr - boost reference. the fuel pressure is 43ish with vacuum - just like it should be per the fsm.
i replaced all of my couplings and pipes to reduce the amount of couplings that i had before because i did have a couple boost leaks. its a jwt ecu set for everything im running.
it ran well initially and then developed this problem. its pretty damned annoying to say the least. i was talking to cody ace the other day and i will be replacing the coil packs - with ls2 coil packs. i think its an electrical problem at the moment.

itwillboost

LOL should have stayed KA :wall:. I would pick up LS2 truck coils, they will fire much stronger, just remember you need to buy the whole harness. Are you set up for data logging if so email me the log. Hopefully it works out.

Did you change downpipe's recently ? How far from the turbo is your o2 sensor ? That or the coil is my guess. Your A/F's don't dip at the higher rpm's right ?

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AdamR

Didn't watch the video. What is the AFR like when it happens?

AsleepAltima

im blaming a coil pack too, at the moment. im going to do it old style and replace each coil one by one till i find it. i dont think its a multiple coil problem. it doesnt seem to do it as bad when its cold, but its still there.


i dont know what the afr's are - i dont have a wideband installed. it may sound silly, but i never ran a wb in my turbo altima because the jwt ecu seemed to be so spot-on, so i didnt bother with this one either. reading my plugs however, they dont look lean or rich - they look just right. i do have a wb sitting here though, i just havent decided if i want it in my evo or the 240 just yet.

AsleepAltima

its the same setup that i ran before the rebuild. it ran smooth as silk until the piston swelled up and killed the rings.
and as far as the ka goes - i loved it on my altima, but i love the simplicity of the sr much much more.

Jesse SR20

This.

Especially since you mentioned re-doing your piping/couplers.

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AsleepAltima

i dont have a boost leak setup anymore but i was pretty careful about these couplings going on. i used new clamps and pliable couplings. the old ones were brittle and the clamps were iffy. i also switched over to a hard intake pipe instead of the soft flexible one. it did this before swapping the clamps though, although it did soften it a bit. the boost leaks were very obvious before, but now its pretty tight.

AsleepAltima

lowered the boost to about 18ish and the problem is gone. im pretty sure its all coil related now. changed each coil out with a known good coil and there was no difference whatsoever.

TheRealSy90

So its obviously not the coil.

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KiLLeR2001

Whats the spark plug gap? Check spark plugs for any irregularities.

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AsleepAltima

how so?
i think its even more pointing to it now.

AsleepAltima

brand new bkr7 iridium ngks with less than 500 miles on them. the gap is .028. i tried all the way down to .022 and no change whatsoever.

jr_ss

Need to upgrade your ingition system. You need more dwell time and you can't do that with factory coils.

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AsleepAltima

i agree with you. i bought some lsx coils yesterday and they should be here to me in a couple days.

AsleepAltima

i took a look at my jwt ecu today and i dont see the recommended fuel pressure on it like the ka-t jwt ecu i had. is it the same? 3 bar? looks im gonna have to call jwt again...

AsleepAltima

anyone what the "12mm" thing is for?

TheRealSy90

Because you said you changed each coil out with a known good coil, and it didn't make a difference. So its obviously not the coil.

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AsleepAltima

im taking back what i said about "known good coil". the one i have with the most resistance made each cylinder it went into, miss. now im not even sure i have a good set of coils. lol

srvnt

bad 5th gear position sensor can do that also

AsleepAltima

not happy about what i found just now - lowered the boost the other day and it was fine... then today, it started doing it again. so i went out to check and double check the fuel pressure again. while i was there, i took a look at the ignitor and the dude that wired it up before i had the car, on the bundle after the ignitor on the engine side, used electrical tape and ran it under the regulator. so i grabbed one of the wires and INSTANTLY, the idle dropped and the engine started to stumble. pinched a couple other wires and the same thing happened... im going to be just as pissed as i am happy if it turns out to be shoddy wiring... well, when the lsx coils get here tomorrow or the day after and i have to eliminate the stock ignitor, i will fix the wires and solder/heat shrink it properly.

PureRush

It's the timing. My Ka was doing the same thing cause it was too advanced

AsleepAltima

i checked and rechecked the timing. it settles right in at 14/15ish.