nfinitecc

i have a Y7 on 5 psi. Greddy kit, spearco FMIC, Vortec FMU, Walbro 255 intank, B&M FPR, 310cc Injectors, Blitz BOV, Apexi timer, all gauges. The car will run perfect for days, then all of a sudden when im cruuising like 40 in 4rth and the rpm's are real low like 2-1800 it starts hesitating and jumping, sputtering, but as soon as i gas it it clears up and takes off fine all the way to redline and pulls hard, ive noticed when it does this it has a slight rughness from vac to boost. But some days its as smooth as can be. im throwing a code for random cylinder misfire on al four cylinders 71-74. ive replaced the cap, rotor, plugs(which look good), wires everything i can think of, its that it runs perfect some days that has me stumped?? can anyone please help me on what else i should check baised on what ive described??? Thanks in advance, im waiting to get the car NEPTUNED but i have to fix this before they'll tune it!

SOHCD16y8

what r your plugs gapped at? You dont use cheap gas do you?

nfinitecc

my plugs are NGK stock gap. no, i only use 93 octane. any advice anyone?

R-Lug

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by nfinitecc &raquo;</TD></TR><TR><TD CLASS="quote"> Vortec FMU</TD></TR></TABLE>

What disc are you running in the FMU, i really hope it's not a 12:1 cuz with the 310's you're running way too rich for 5lbs of boost.

Why are you not running the blue box?

When you get Neptune, you're going to ditch the FMU anyways, so just go ahead and get it Nepuned.

nfinitecc

the car had the greddy kit with FMU when i bought it, i added everythin else on it. it doesnt sout out the exhasut very much at all, it used to when i bought it but now it runs clean. i just need advice on how to fix my random cylinder misfire problem at low RPM cruising speeds i dont boost on it much i just have to get that fixed for neptune.

nfinitecc

bump! so with 310's, a high flow pump, and slightyly raised Fuel preasure do i even need the FMU anymore?

bubs

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by nfinitecc &raquo;</TD></TR><TR><TD CLASS="quote">bump! so with 310's, a high flow pump, and slightyly raised Fuel preasure do i even need the FMU anymore? </TD></TR></TABLE>

YES! Even with slightly larger injectors, you'll lean out really bad without some kind of fuel management. I'm also running an fmu and had a similar problem with the random misfires. I ended up changing the plugs and it took care of the problem. You should be gapping them at around .30 though, the stock gap is too large for boosted applications.

dpetro1

^^^beat me to it

if you arent running a chipped ecu with some type of engine management then you need the fmu regardless of injector size. your stock ecu wont add fuel for boost so thats what the fmu is for.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by SeaLevel &raquo;</TD></TR><TR><TD CLASS="quote">What disc are you running in the FMU, i really hope it's not a 12:1 cuz with the 310's you're running way too rich
</TD></TR></TABLE>

this may be the problem. you might want to look into a 10:1 or 8:1 fmu or just go ahead and get the neptune.

nfinitecc

ok, im gonna try the .30 gapped plugs when i get off work, if the FMU is causing the misfires then im just gonna get the neptune and see what happens. i'll be running RC 550's injectors, 3 bar map and ditching the FMU 10 PSI!! Thanks for ya'lls help, any other ideas come to mind keep em' coming

nfinitecc

SOHC_MShue

ditch that hacked together fuel managment setup for something that works. For now I would at least ditch the 310cc injectors because on 5psi the fmu should be enough. The larger injectors will just make your car run like crap out of full boost.

nfinitecc

awesome im getin some answers, im just gonna tough it out untill tuning. keep it comin

marcussmith26

Hey man i had this problem i ended up haven to close my plug gap to .25 to fix my problem, you also need a colder plug. You may already know this just tring to be a help if can

nfinitecc

alright ive been on the phone all morning try to find a colder set of plugs with .30 gap but im having no luck, do i need to just close the gap on my existing plugs? but id rather have a colder set as well. a website would be awesome!!

SOHC_MShue

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by nfinitecc &raquo;</TD></TR><TR><TD CLASS="quote">alright ive been on the phone all morning try to find a colder set of plugs with .30 gap but im having no luck, do i need to just close the gap on my existing plugs? but id rather have a colder set as well. a website would be awesome!!</TD></TR></TABLE>
it doesn't sound like the plug gap is your problem. If you were missing in high rpms at WOT then yes that could be the problem, but with it just stumbling transitioning into boost and in cruising speed that is not the plug gap.

However I would gap your plugs lower and maybe get 1 step colder if you can, but i don't think the plugs you have now will be much of a problem at 5psi.

sneakypete

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by nfinitecc &raquo;</TD></TR><TR><TD CLASS="quote">alright ive been on the phone all morning try to find a colder set of plugs with .30 gap but im having no luck, do i need to just close the gap on my existing plugs? but id rather have a colder set as well. a website would be awesome!!</TD></TR></TABLE>

Your fouling your plugs with all that fuel. Buy some new sparks plugs and get neptuned.

Here's a link for the spark plugs, phil can help you.

https://honda-tech.com/zerothread?id=1405006

nfinitecc

thanks, keep the ideas flowin

Importordomestic

bushings in the distributor worn out causing the shaft to have alot of play. causing misfire...

could be possiable my accord did that with 2 dizzy's

nfinitecc

wouldnt this cause misfire though at all levels I.E. Idle, WOT ect... thankyou for you input though no suggestion ignored

Weq

i had the same misfires at low speeds. its plugs.

SOHC_MShue

If something is wrong with the dizzy causing it to miss I still don't see why it wouldn't miss in high load and rpm situations. I still say its the fuel setup causing it to hesitate transitioning into boost. I've seen it happen before on my friend's hacked together fmu + afc + large injector setup. I had the afc set to -50% straight across the board and it would run insanely rich at anything other than wot and if you tried to boost part throttle it would buck and do all kinds of crazy **** from running so rich.

nfinitecc

yea i understand that the FMU is why my transition into boost is so off, its the low rpm misfires that have me stumped, but after tuning tommorow it'll have 550cc injectors, no FMU, and .30 plugs 1 step colder. neptune, if that doesnt fix my problem then Ill be back! thanks everyone

SOHCD16y8

good luck

teler86

keep us posted

nfinitecc

for sure