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2.5T_/<ouki
11-01-2011, 12:28 PM
Thank you for taking the time to view this. Much help is appreciated.

I've got an RB25 in my s14 and everything has been running great until about a week ago. My car/engine seems to be giving me some "sputtering" problems while driving. I notice it way more when just city driving, maybe half throttle, however i still notice/feel it at WOT.

Say I'm driving around about half throttle going about 50mph, my car suddenly feels like it stops, then picks up again, stops then picks up and doesn't really feel like its building much boost. Sorta like if you were to push a milk jug thats full, you know how it will slide, then stop then slide a bit more then stop? It feels as if my car is doing that.

The only thing that i have changed is my FPR vacuum line and BoV vacuum line, and the only thing i did was just switch the ports. I have a Greddy IM with 4 vaccum ports on the backside of the IM. All i did was just move from port 1 to port 3 for the FPR and port 3 to port 1 for the BoV.

Where should i begin looking? I've inspected to see if any of my couplers have come lose but couldn't detect anything like that. What do you guys think is going on? Thanks again for the help!

2.5T_/<ouki
11-01-2011, 02:13 PM
Going to try and check the Coil packs & Spark plugs!
Been reading on some other forums and it seems it's usually the coil packs having a hairline crack!

filipino4life92
11-01-2011, 02:47 PM
boost leak, vacuum leaks, you got AFR gauge?

2.5T_/<ouki
11-01-2011, 04:00 PM
boost leak, vacuum leaks, you got AFR gauge?

No boost leaks have already checked for this (would have seen that if you read my post). No Vacuum leaks. I do not have an aftermarket AFR gauge, however i do have the one that uses the stock o2 sensor via the Apexi auto timer.

It starts to lose power around 4,500 + RPM's. Just like this thread. I've been reading a lot of these threads stating it loses power around 5k (which mine does exactly this!)


RB25DET Sputtering Problem SOLVED : RB20DET / RB25DET / RB26DETT Forum (http://forums.nicoclub.com/rb25det-sputtering-problem-solved-t410370.html)

filipino4life92
11-06-2011, 11:51 AM
yeah i read that you've seen that couplers are fine. i mean just regular vacuum hoses. shoulda been more specific.

have you done anything that that thread has done?

my problem was in the same rpm band as yours on my rb20det. all i did was adjust the fuel pressure. i just had to raise it a little bit, i'm at 37psi no vaccuum right now. also checking timing would be a help