RB25 Misfire, Poor Idle, ETC :(

[FinkenS14]

Hey guys my RB is still having problems. Recently it got a really lopey idle, and sometimes, start loping so bad that it almost dies, I have to keep my foot on the gas to keep it from dieing. What could be causing this other then a vacuum leak? Because Im pretty sure its not one.

Also, now it climbs through stock boost awesome, but has a slight studder, but if I let off from just going WOT, the car will get really quiete, its still running, with my foot slightly on the gas, and then it comes back to life, then goes quiete again, then comes to life again, almost like fuel or ignition is shutting down? Im running an atmospheric BOV, could this be it?

But the thing I dont get is its fine sometimes, and other times the problem is horrible where I can even keep it at the speed limit because the throttle doesnt respond, bad TPS maybe? But how would that cause a studder?

I also grounded my ignitor to the firewall, and that didnt seem to help at all.

Im lost guys, any help would be great.

Mods

S1 RB25 S14
CX Racing IC
HKS SSQV
Greddy Intake
Stock TB
Yamamoto Tuned ECU (came with the motor)
Walbro 255

NOTE: Im currently running an open turbo elbow till Wednesday when I get my exhaust put on.

Everything else is totally stock on the car, even the boost is at stock 7psi.

[FinkenS14]

Just found my front knock sensor was unplugged. Possible lead towards my problem?

[steve shadows]

Doubt it worth a try though.

I woudl check all of the obvious things first.

Grounds for ignition and wiring harness
Spark Plug gap and condition
Vacuum Leaks

[FinkenS14]

Plugged the knock sensor in, went for a spirited drive, let it idle for about 10 minutes, doing just fine.

Checked plugs, little greyish brown, but look the same the day I bought them.

Grounded out my ignitor, and checked and tightened any grounds i got.

[wiley81690]

I need help trying to diagnose my rb25det swapped s14. I have a Greddy intake, 3'front mount,3' turbo back exhaust,Walbro fuel pump,apexi intake,BCU4 boost controller,aluminum radiator, everything else stock. Almost three months ago my injectors all the sudden stuck open, causing my car to over fuel and die.So i replaced the injectors with larger ones(660cc) may be slightly to large. But after that no start. I retimed the engine...no start. So i determined my ecu over worked my coils or ignitor. So i got a new ignitor and the NZ pink coils. Still no start. I pulled out my main harness(with injector and coil harness)and cleaned them up, changed my oil, and to try to prevent the rings washing out i dumped a small amount of oil on top of the pistons and turned it over with no fuel,bought new NGK iridium plugs. After all that i compression tested it, and all 6 came out to 65lbs after 4 turns. Which is way low, but i decided to put it together and try anyways. And it started, rough as hell but it runs. I am currently trying to fix a miss on #5. I tried mixing up the coils and injectors, miss stayed on #5. I checked my grounds they were all good. I noticed with a test light i had no power on the out side of the ignitor for #5. I jumped a wire from the ecu to the in side of the ignitor and got power on the out on #5. But still has a miss. Are my rings toast on #5 or #6... Ecu bad? I am out of ideas and have no experienced shops anywhere close. Thanks

[Bentleyness]

Not a rb but when my ka-t missed it ended being a bad injector seal causing a flood and not firing. I fixed the seal and now it don't miss. This just an option

[Sileighty_85]

I need help trying to diagnose my rb25det swapped s14. I have a Greddy intake, 3'front mount,3' turbo back exhaust,Walbro fuel pump,apexi intake,BCU4 boost controller,aluminum radiator, everything else stock. Almost three months ago my injectors all the sudden stuck open, causing my car to over fuel and die.So i replaced the injectors with larger ones(660cc) may be slightly to large. But after that no start. I retimed the engine...no start. So i determined my ecu over worked my coils or ignitor. So i got a new ignitor and the NZ pink coils. Still no start. I pulled out my main harness(with injector and coil harness)and cleaned them up, changed my oil, and to try to prevent the rings washing out i dumped a small amount of oil on top of the pistons and turned it over with no fuel,bought new NGK iridium plugs. After all that i compression tested it, and all 6 came out to 65lbs after 4 turns. Which is way low, but i decided to put it together and try anyways. And it started, rough as hell but it runs. I am currently trying to fix a miss on #5. I tried mixing up the coils and injectors, miss stayed on #5. I checked my grounds they were all good. I noticed with a test light i had no power on the out side of the ignitor for #5. I jumped a wire from the ecu to the in side of the ignitor and got power on the out on #5. But still has a miss. Are my rings toast on #5 or #6... Ecu bad? I am out of ideas and have no experienced shops anywhere close. Thanks

Is your "Enter" Key Broken on your keyboard?

Is your ECU even tuned for those injectors?

Stocks are 370cc so you've almost doubled that...

[feito]

i had a similar problem with my rb when i installed it: it also turned out to be a disconnected knock sensor