rb25 problem

[240sxwanted]

So today i replaced my old sparks on my s2 rb25det which some ngk iridium 7 that are factory pre-gapped. The ones that were replaced were the ones that originally came with the engine. They were some ngk iridium 5. The reason i replaced them is because once the engine was warm i was experiencing some bogging and power loss when i got on the gas hard, but at light throttle it rev perfectly fine, but as soon i stepped on the gas pedal all the way it bogged and it seemed to have a power loss. Its pretty much a stock rb25, mods include: isis intake manifold, stock throttle body, fmic, stock skyline radiator, stock turbo with rb20 actuator (10 psi). The turbo that is currently installed is a replacement, the original had an rb25 actuator and blew about two months ago. I can't really remember if i had this issue when i had to original turbo, i guess because i just had the swap done and didn't want to push it hard. When the rb is cold or not at temperature, it runs really good. It pulls very hard as it should. But as i stated, it seems like it bogs and loses power when he car is warm and i step on the gas all the way. Today i also taped up the coilpack boots really well along with replacing the spark plugs. After doing this I decided to take it for a drive while the engine was warm. It seems like the spark plugs helped somewhat of my problem, but it doesn't feel like im getting all the power like when the rb is cold. Could it be that I need new coilpacks?

[240sxwanted]

damn, no one has any input? well tomorrow im going to replace the coolant temperature sensor and sender unit and see if i still feel the power loss while the engine is warm

[flatrate]

check for boost leaks?

shouldnt be beating on a cold engine anyway

[Joe]

um you shouldnt be driving hard when its cold. problem solved.

[240sxwanted]

no boost leaks for sure. Im not driving the car hard when its cold, im just saying that theres a huge power difference when the car cold than when its up to temperature, and not driving thecar hard when its doesnt solve my problem. Well tonight i will replace the ect and sender unit and see if that solves my problem

[Joe]

yea ever think its a built in safeguard in the ECU because your engine isnt up to temp?

[240sxwanted]

yea ever think its a built in safeguard in the ECU because your engine isnt up to temp?

i dont think u understand what im trying to say. once its up to temperature, the car loses the power and bogs a little, but when its somewhat cold there is no lag at all and feels strong

[Joe]

hahaha my mistake. im just an ***hole, ignore me

check your plugs, gap and timing. those are always 3 culprits of bogging

[240sxwanted]

timing is good. the plugs and brand new ngk irudium 7, and were pre-gapped. therefore, i didnt check the gap on them. from what ive researched on this forum, it could be the coilpacks, engine coolant temperature sensor and sender unit, and spark plugs. I've replaced the sparks so far, and tonight i will replace the sensor and unit. So i will update this thread tonight, hopefully with the problem solved

[Joe]

what is your timing set at?

and you still need to check the gap on those plugs. just because they are ngk iridiums doesnt meant they are going to work.

and for the future, a copper core plug will work better in your RB.

[StricNyne]

yeah bkr7e aka 4644 is the bomb! i would look into the timing like Joe said. if it was coil pack it would probally be a misfire, are you running any kind of engine management ? or do you have any way to monitor what computer is doing ?

[240sxwanted]

so i replaced the sender unit on the rb. As far as the sensor, i will it replace soon.

[240sxwanted]

replaced the engine coolant temp sensor and still havent solved this issue. I've replaced the iridium 7's with the copper 7's that everyone says theyre better for the rb. Also i tested out my friends ls2 coilpack setup on the rb and still hesitated a bit and lost power at high throttle. notice that the car runs really great with no lag or hesitation or anything, runs like a champ so to speak when its not at that operating temperature yet. but as soon as the car hits that temp it starts acting up. Does this even with the ls2 coils. any help?

[StricNyne]

hmmm i went standalone just to dodge things like this idk, maybe knock and ecu is pulling timing ? do u have anything to monitor with

[240sxwanted]

nothing to monitor as of now, but i purchased an safc2 and nismo fpr. going to get a wideband pretty soon too. maybe with these upgrades i will know wtf causes this to happen

[Joe]

what is your timing set at?

and you still need to check the gap on those plugs. just because they are ngk iridiums doesnt meant they are going to work.

and for the future, a copper core plug will work better in your RB.

*cough*

[flatrate]

i have had better luck with the iridiums, on my setup

[240sxwanted]

gap is at .8mm on the coppers, timing is good

[rb25det250sx]

what is your ignition timing set at? not mechanical/belt timing.

[Joe]

gap is at .8mm on the coppers, timing is good

dont just say its good, what is the number.

[240sxwanted]

Sorry guys, dont know what exactly the timing is at. The swap was done for me by a couple of guys. From what i was researching, shouldn't the timing be at 15 degrees? Also, if by any chance my timing isn't at 15*, would it cause the rb to perform much better when its cold (not at operating temp) as opposed to when it reaches that operating temp?

[rb25det250sx]

yeah, my Rb had skipped a couple teeth(luckly no damage) and was either retarded or advanced on timing(can't remember) and it would run fine at first start untill it got warmed up, then the ECU started pulling more timing to compensate and would overheat very quickly.

[240sxwanted]

so i verified today, and the timing is at 15 degrees. ran out of ideas guys. could it be that the engine coolant temperature sensor is not getting any power?

[StricNyne]

can u monitor knock ? if u running oem ecu it might be pulling timing when it sees the knock, uhh try swapping cas, i am stumped, maybe a real dyno, or check maf ? its probally something stupid

[Darius]

What fuel pump are you running and how old is it? Are you able to monitor your fuel pressure under boost?

[240sxwanted]

im running a walbro 255, ive had it for almost a year and a half. i bought it used. I cant monitor fuel pressure under boost. still running stock fpr. Will install safc2 and nismo fpr next weekend to compensate if im runing lean, due to the fact that i have that rb20 actuator for 10psi

[Darius]

Go to autozone and rent one of their fuel pressure gauge kits. It has a long enough hose that you can extend it from your fuel feed line up to the windshield so you can watch it while you drive. That way you'll be able to see what the fuel pressure is under boost. Please report the peak fuel pressure at 10 psi of boost back to us. It should be 43.5+10 psi (boost) = 53.5 psi. If not, there's a problem with the walbro or there is a clogged filter/line.

[240sxwanted]

ok guys i fixed my problem. the timing wasnt staying at 15*, so what i did was unplug that brown plug behind the intake manifold and set the ignition timing to 15* and plugging back in the brown plug so it locked in the timing. Plus i got the car tuned with an safc2, and upgraded to a nismo fpr (set fuel pressure at 50 psi at idle). Now it runs like a raped ape. Thanks for all the help guys.