RB25 hit 4k instantly goes rich - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

max1008 · 09-21-2015, 06:42 AM

Hi all, I've been trolling here a while and a few months ago finally signed up. I own a 95 S14 with an Rb25 s2. Car has been running great. it has:

new BCPRES plugs heat range 7
new Benchmark Coil packs
z32 maf
freddy intake
q45 throttle body
stock injectors
FMIC
stock turbo
RS Enthalpy tune
Blitz SBC running 13lbs of boost

Everything was running good until I temp. relocated my catch can closer to my intake and it was venting right into intake filter. So I moved it onto the other side of the bay. Had to take MAF out completely clean that. I did a seafoam into the gas tank, seafoam into the brake booster vac line.

After car ran really good. But now car is running really rich the moment I hit 4k rpms the fuel drops from 10.8 - 11 all the way down to 9.6 - 9.8 (like a light switch). It's not sputtering or jerking, it just goes flat.

Has anyone had anything similar to this happen? My plan is to take it to a buddy's shop and pull codes hopefully tomorrow. At idle my vac is anywhere from -18 to -20, I would think if I had a vac leak it wouldn't go rich like that I would see it across the band. It doesn't matter if it's floored or if I'm half way into the pedal, it hits 4k and it starts dumping fuel.

Feast Japan · 09-21-2015, 07:36 PM

A few simple checks: try another O2 sensor & also test fuel regulator.

bookegbn · 09-22-2015, 07:27 AM

well,i think so, thank you

KAT-PWR · 09-22-2015, 08:57 AM

Boost leak

asiannshit · 09-25-2015, 05:06 PM

Temp sensor or fpr

*Nissan2nr22* · 09-25-2015, 05:07 PM

Prob temp sensor

Sinamex · 09-26-2015, 01:34 AM

sounds like temp sensor

09-21-2015, 06:42 AM	#1
max1008 Join Date: Apr 2015 Location: Florida Age: 42 Posts: 13 Trader Rating: (0) Feedback Score: 0 reviews	RB25 hit 4k instantly goes rich Hi all, I've been trolling here a while and a few months ago finally signed up. I own a 95 S14 with an Rb25 s2. Car has been running great. it has: new BCPRES plugs heat range 7 new Benchmark Coil packs z32 maf freddy intake q45 throttle body stock injectors FMIC stock turbo RS Enthalpy tune Blitz SBC running 13lbs of boost Everything was running good until I temp. relocated my catch can closer to my intake and it was venting right into intake filter. So I moved it onto the other side of the bay. Had to take MAF out completely clean that. I did a seafoam into the gas tank, seafoam into the brake booster vac line. After car ran really good. But now car is running really rich the moment I hit 4k rpms the fuel drops from 10.8 - 11 all the way down to 9.6 - 9.8 (like a light switch). It's not sputtering or jerking, it just goes flat. Has anyone had anything similar to this happen? My plan is to take it to a buddy's shop and pull codes hopefully tomorrow. At idle my vac is anywhere from -18 to -20, I would think if I had a vac leak it wouldn't go rich like that I would see it across the band. It doesn't matter if it's floored or if I'm half way into the pedal, it hits 4k and it starts dumping fuel.

09-22-2015, 08:57 AM	#4
KAT-PWR Nissanaholic! Join Date: Dec 2011 Location: US Posts: 2,040 Trader Rating: (11) Rides Gallery: KAT-PWR Feedback Score: 11 reviews	Boost leak __________________ MRP Manufacturing

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09-21-2015, 07:36 PM	#2
Feast Japan Zilvia Junkie Join Date: Aug 2009 Location: Canada & Japan Age: 42 Posts: 422 Trader Rating: (9) Feedback Score: 9 reviews	A few simple checks: try another O2 sensor & also test fuel regulator.

09-22-2015, 07:27 AM	#3
bookegbn Join Date: Sep 2015 Location: CA Age: 36 Posts: 2 Trader Rating: (0) Feedback Score: 0 reviews	well,i think so, thank you

09-25-2015, 05:06 PM	#5
asiannshit Join Date: Sep 2015 Location: Ft pierce Age: 34 Posts: 1 Trader Rating: (0) Feedback Score: 0 reviews	Temp sensor or fpr

09-25-2015, 05:07 PM	#6
Nissan2nr22 Premium Member Join Date: Aug 2008 Location: USA Posts: 1,566 Trader Rating: (30) Rides Gallery: Nissan2nr22 Feedback Score: 30 reviews	Prob temp sensor

09-26-2015, 01:34 AM	#7
Sinamex Join Date: Apr 2015 Location: Whittier, Ca Posts: 47 Trader Rating: (0) Feedback Score: 0 reviews	sounds like temp sensor