breaking up in boost

[240s_are_the_best]

okay, i have a 8:1 FMU, bkr7e plugs, new cap and rotor, and i am running 7-8psi. It usually only does it when warm but sometimes when cold. When i build more than like 5psi it starts cutting out and like falls on its face. i have stock injectors and a blow through MAF setup.
Do i need to close the gap on my plugs to .28 or .30? i think they are at like .35 or .40.
do i need a 225 fuel pump? as i still only have a stock one.

[Chris28]

Get a 255 lph fuel pump, that's a start. You might also want to get a 6:1 FMU, I think 8:1 is too rich.

Try .034 for the plugs, and check/replace your wires. I had hardcore breaking up in boost issues when I first went forced induction, turns out one of my plug wires was broken and grounding itself to the valve cover. Took forever to figure out as they all looked just fine.

[240s_are_the_best]

okay. im in the process of ordering a pump. can i get just a universal one or does it have to be for an s14?

and could i just do to 10psi instead of getting a new fmu? or would that be pushing my luck with stock injectors, no tune, and a rebuilt to stock bottom end (new .020 rings and pistons, king rod and main bearings, and felpro headgasket)?

[Chris28]

I think there's something about s14 pumps and the fuel sock, but I'm not sure. From what I recall you need to re-use your stock fuel sock with the Walbro instead of using the one provided with the kit. The pump itself doesn't matter though so if the auction is for s13/s14/s15 it will fit.

I wouldn't recommend 10 psi with an FMU setup, just get a 6:1 and call it a day. What size turbo are you running? If it's a t25 then 10 psi is already pushing it, around 11-12 psi it just turns into a heat pump.

You have retarded the timing a few degrees, correct? That is necessary when going with the FMU setup.

[240s_are_the_best]

I have a t3/t4 with an external wastegate with a 5psi spring and an ebay MBC set to like 7 or 8 psi havent been able to get it to go full boost because of the sputtering. i think it is spark but i am not 100%sure i have not put plug wires on it since i bought it and i have no idea when the previous owner did them. and i am pretty sure that it did not do this when i first done the setup. I am running a top mount setup so maybe the heat finished off the wires. i plan on getting a new set tomorrow and getting some thermal cloth and wrapping the wires. and yes i have pull ~2-3 degrees at the distributor. it done this before and after the engine rebuild, but worse after because i never really drove it more than a few miles because i was going to "break-in" the turbo and my engine had like 120psi compression and i didnt wanna completely kill her.

[Chris28]

It does indeed sound like spark. When my engine did this it did it once or twice while N/A. Whenever it happened I would take the spark plugs out to see if they were bad. I ended up just putting them back in and the problem stopped so I didn't think anything else of it. In hindsight it was moving the wires as I pulled the plugs that caused one to stop grounding.

[240s_are_the_best]

okay thank you for all your help. i cant find plugwires ANYWHERE!! but ill get some. but until then do you think it will stop if i put the stock plugs in it?

[C-Kwik]

Try gapping down the plugs more before getting new wires. Its been years since my KA-T, but I recall being down in the 0.02x range. A bad cable will probably also show up as misfire even at idle in most cases. And even more likely that you'll notice a single cylinder miss at high RPMs even at light loads.

[WDRacing]

Just personal preference, I won't close a gap further then .028. If you're still getting blow-out at .028 you need more spark power.

Don't add anymore boost with an FMU. It's to much fuel pressure, even with the 6:1 I wouldn't run more then 8 psi. Like Chris said, make sure your timing is bumped back a couple of degree's just for safety. Bumping the timing back some will reduce the cylinder pressure to avoid knock and it may also help with the spark issue.

[240s_are_the_best]

okay i drove the car today and it did not do it.. i ordered a set of plug wires yesterday and i am going to get them tomorrow. i pulled #1 plug and it was at .030 and looked a little rich. maybe the 8:1 is just a little to rich... its an obx ebay one(gotta love gifts ) is there any way i can modify it to be a 6:1?

[240s_are_the_best]

I got her fixed i put 8mm plug wires on and regapped my plugs to .028. i threw a timing light on it just to check and it had advanced itself to ~15* BTDC so i set it back to ~22-23* and drove her around the block a few times and wala! thanks for all the help! and as for the 8:1 i think i am just going to keep it until this fall when i get the money for an AEM F/IC and some 370ccc SR injectors and a wide band. I have a narrowband A/F gauge now. the 8:1 just gives me a little bit of piece of mind so i KNOW I dont go lean, I dont really trust my air fuel gauge haha. does anyone see any problem with my plans for the fuel control? anything i missed? sorry im still kinda newbish when it comes to forced induction..

[WDRacing]

The timing shouldn't be any further advanced then 20* and I'd recommend backing it off unless you have another means of retarding the timing on boost.

[240s_are_the_best]

okay. so when you say "bump the timing back a few degrees" you mean aroun 17 or 18 instead of 20+. correct?

[WDRacing]

Exactly, 17 or 18 would be perfect for 8-9 psi. I would run no more then 7 psi with 20* of timing which is the stock setting. My general rule is .5 degree's of timing retard for every 1 psi over 7. This is assuming you have an efficient fmic and your car is tuned fairly decent.

[240s_are_the_best]

well like i said i am only using a VERY basic setup with an 8:1 OBX FMU and a stock 96 ECU.

[s13drifter88]

ka's run 17-20* stock so for boost id retard to about 13-15*. swap your plugs and close your gap to .8mm. if theyre fouled or about worn out u could possible be blowing the flame out. fuel pump upgrade is a must. id get a walbro 255 ($100) or if i couldnt afford id go to a junk yard and grab either a j30 pump or a q45 pump both are good to 325+ easily

[GEO]

Get a 255 lph fuel pump, that's a start. You might also want to get a 6:1 FMU, I think 8:1 is too rich.

Try .034 for the plugs, and check/replace your wires. I had hardcore breaking up in boost issues when I first went forced induction, turns out one of my plug wires was broken and grounding itself to the valve cover. Took forever to figure out as they all looked just fine.

Ha I HATE FMU's.. but I would recommend getting bronze spark plugs with a heat rating of 7 and key them at 0.035.. Ran this setup for over 5 years without any problems on 10psi.

[Blown240sx]

SUMMARY

Plugs

7-8 heat range (for NGK since their heat scale is reversed)
Copper is optional

Gap for low boost

0.030-0.035

High Boost

0.028-0.030

Timing

I set to 15* on KAs. Ive seen plenty of KAs mess up at 20*

[ka-t4u]

whoa whoa whoa wait.... "retard" timing to 15*??? i thought you retarded timing to 20 plus degrees like 22 or something.... isn't 15* "advanced" timing?? am super confused now.....because am still NA and i "advanced" my timing to 15* and it made it run stronger. so confused right now i thought to retard timing meant to take it to 20* or more.... correct me if am wrong...

[Blown240sx]

When you set timing with a timing gun for the BASE timing you line the point up with the 4th mark to the right of TDC. That is equal to 20* of BASE timing.
If you move it back 1 mark it removes 5* of timing. Thus your base timing is 15*. This will bring your overall map of timing DOWN 5*.
This makes for a safer running car because most people dont have standalones on their KAs to control the ECU advanced timing.

[ka-t4u]

so by setting my timing to 15* BTDC i actually retarded the timing map on the ecm? you are refering to the timing map n the ecm right?? am so confused.... if factory BASE timing is set to 20* BTDC and you move it to 15*BTDC isn't that advancing??

[s13drifter88]

no because ur taking away timing or "making it fire later" rather than sooner so it been retarded. u do this to prevent detonation. na ka's run between 17-20* at base, 20 performs the best. for boost i.e. ka-t should be aroung 13-15* base to avoid detonation. for a basic t25 @ 8-10psi, generic intercooler, sr 370's, safc, n60 maf ect ect 15* should be just fine. for anything more i.e. t28 or larger above 10psi, s15 440's ect ect id drop to 13* for safety. youd prob be fine at 15 but i dont want anyone to pop anything and hate me so imma say 13 lol

[s13drifter88]

also for plugs id gap at .9mm for a basic low boost t25 setup, anything more id go to a .8mm which is like .028 or .029