Ok so recently i have been getting a bit of a break up in my race car. last outing at the track it was misfiring as well. The car sits often. It feels to me as the high temps recently have been causing it but i know its not the case. I have tried gaping my plugs fron .018-.026 without seeing much for results, changed cap and rotor, still nothing, it has a after market internal coil from accel which could be crapping out and i guess is my next route. now for the basic setup, d15b vitara eagle setup, C16 stock ignition, tuned at 25 psi, s300, stock head 880's ect. When the car was tuned (morgon from synapse) temps were in mid 40's and very blustery, plugs were set to .022 during tuning. Is there a misfire monitor on the s300 or anything like that? any help would be great, if you need more info/tune calb/datalogs/ lemme know. ill take some vids of it to try and help. thanks in advance guys!!

 

also if my wideband 02 crapped out would this cause this? before i touch the gas it idles around 14-6 once i bring up the rpms then let off it will go to like 18-19 at idle, i know leaded gas does a number on these sensors so just trying to rule things out.

 

bump

 

i would deff look in to going back to the oem coil.
ive known so many people that had problems after a while with external coils.

could be old gas to but it would be noticeable at idle most likely.

 

its still an internal coil that goes in the dizzy its just an aftermarket one, never really had any issue with it but im gonna try the one of my hatch and see if that changes anything,

bump, could my race fuel have gone bad in a year of sitting? its in vp jugs but stored in my trailer which gets very hot

 

bump, any other things to check?

 

Ok so here's an update, found that my fuel had deff gone bad, smelled like varnish, so i have emptied my tank, fuel was deff junk smelled like varnish, poured some 93 in and ran for a while, also took the pump out to examine, was coated thick white i assume from heating up and always running low amount of fuel, so now the miss has gotten worse i feel, it will do it all the way up if you rev slowly, noticed fuel presure on my gauge mounted on the fuel rail was only at about 35 at idle, when you rev up it jumps up slightly then drops alot, also when you prime the pump the pressure jumps to 35 then goes back to 0, doesn't it normly stay primed, holding pressure? so i am thinking i have a fuel delivery issue here, pump maybe starting to go out? (walbro 255) gonna try getting new fuel filter, bad injector possibly? any way to test any of this through the s300? Thanks in advance

 

could a bad dizzy be causing this mis?

 

You may check what the fuel pressure is with the car idling and the vacuum hose disconnected. Should be at least 45psi (stock)

 

so little update, i have emptied tank, put fresh c16 in, new walbro 255 and sock, new fuel filter, swapped ignition coils, plug wires, still nothing, seems to be happening at any rpm which you hold the throttle at, only when the throttle is being held steady, quick revs are fine with no miss. Is this an injector problem? i have precision 880's P&H with resistor box wired in, resistor box turns on and stays on so i assume nothing there. Fuel pressure with vac line on is around 37 and vac line off around 45. I am stumped here and have a big event comming up in 2 weeks, any help would be greatly appreciated