miss under wot.

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Jmcc
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miss under wot.

Post by Jmcc »

ight i dorve the car 2 weeks ago and all was good. pulled the 40 out this moring
drive fine. just under a wot pull it hits 3800 and starts to miss and stuble going through
the rpm.

so i did a data log couldn't find any thing out of the norm.

afr's seem good but i have had problems with the wideband before. the timing and pulse with, map and every thing els seems good like the last data log i have.

all tho it is 20degrees colder than the last time i had it out. my iat's correction doesn't seem to be add a ton of fuel and tps seems to fine it reads steady the hole time.

setup stock ka. header, full exhaust, dual 91 cams, ms2 no maf no idle controls and only one vac line. and


the one thing i can think is i burnt another cylinder, or my msd coil is starting go.


i dunno let me know what you guys can think of.
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airman
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Post by airman »

What plugs and what are they gapped to? My car would miss horribly with BKR7s at 0.034", but at 0.028" haven't had a hiccup yet. Hard to believe but 0.006" made all the difference in the world.
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Jmcc
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Post by Jmcc »

remember no boost. and i do not remember. but its seems a few points leaner than before tho. im gunna thos some more fuel at it and see what i get. the last time i messed with the tune it was about 90+ out side lol.
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Jmcc
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Post by Jmcc »

well i got first to run out with out missing a beat but 2nd still f'ed for some reason. o well don't care any more.
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NeverSatisfied
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Post by NeverSatisfied »

Was it misfiring, or more like a fuel cut? If so it might be your tps. I'd check spark first. Maybe pull the plugs and make sure they're not fouled up burning **** they shouldn't be.
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Jmcc
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Post by Jmcc »

the first thing i check was the plugs to see the color. thay are fine, it also has a bright orange spark from the dizzy all the way to the plug's. it will be a stumble to back firing out the back. only under wot tho.

i pulled some fuel and no help added fuel no help. but i did change the dwell setting for the coil and got it only to start doing right around 4.5-5k when it really starts to open up and pull. im going to change to an open element style iat sensor, cause its a lot faster
at reading temps. and go to a hotter plug and see what happens. i really don't think the car is pulling in 102 degree air in 59-70 degree weather even tho its pulling in air out of the engine bay.


also for the tps. its will hold 100%-102% all the way through. but the wot pull is a mix of map and tps. and i have enough cell in my maps to make for eny little up in down under wot loads. the highest and the lowest map will go, ( and this is kinda what states engine load even tho its not) to min at wot right at 4.5 will read 95% and it will not go any higher than 104% so i know its not going into any type of part throttle loads or crusing loads.
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Jmcc
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Post by Jmcc »

got some new plug for the car, she runs fine now. just a little on the rich side still.
but nothing i can't fix. it just don't seem right those plugs wern't in their but maybe 1k miles. o well
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Post by p00t »

Jmcc wrote:the first thing i check was the plugs to see the color. thay are fine, it also has a bright orange spark from the dizzy all the way to the plug's. it will be a stumble to back firing out the back. only under wot tho.
This stood out for me. Orange spark is a pretty cold spark, blue/purple is the color your spark should be. Was this with a ton of gap or what? New plugs will bandaid it for a short bit but if you have orange spark across the plug gap then you need to check power/ground at the coil and possibly switch back to OEM to see if it improves. Cap and rotor too.
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Jmcc
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Post by Jmcc »

thanks for the post. there is some more stuff i need looking into. haven't had much time in the last couple weeks to even look at the car.
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Jmcc
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Post by Jmcc »

i got it fixed for now. i havn't had much time to even look at the car. but i finaly had a slow day at work. i added some dwell for the coil and had fixed the miss under high load. but i think the coil is starting to go bad.
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Post by nismoautoxr »

Dont know what your dwell is but 3.5 ms should be plenty if that helps .BTW if you want more spark buy this viewtopic.php?t=54796
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Post by Jmcc »

i had to bump it to 4.5 to fix it. 3.0 or 3.5 was where it was at. and thanks for the offer but im already on a ms and i am wanting to go cop. but thats down the road a bit more.

add on: the first time i messed with the dewll it was for battery correction, so for got about the one just for the coil. :oops:
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