Rb25det neo running rich and idling rough - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

SilSanti · 07-26-2020, 07:04 AM

Hey guys,
I usually don?t make posts but I?m really scratching my head on this one and I can?t find any useful information anywhere. For context I drive an S13 with an RB25DET Neo. Recently I?ve decided to do rebuild and refresh the engine after tracking my car a couple times. About a month ago I had been experiencing lean issues where my car would hang between 13-15 AFR on WOT. Very unhealthy. I knew I couldn?t let it continue to run so lean. This is an issue that happened pretty suddenly. Previously I hadn?t had this issue, it just kind of happened. I changed my O2 sensor, both coolant sensors by the manifold water neck and cleaned my Maf. Did nothing for the AFRs. I got my ECU checked out by RS enthalpy. They tuned the ecu for my setup so I figured it wouldn?t hurt. It came back fine. I didn?t know what the issue was so I decided to let my car sit for a couple weeks until I decided to do my rebuild. About a week ago I started her up to take her to my buddies shop and she was chucking smoke. Tons of gas. I limped it to the street and began diagnostics. I couldn?t find an immediate issue, but it would not idle unless I kept it revved up. The only way for me to get it to my friends house was for me to drop the fuel pressure on my FPR to around 17psi. It was running at 43 psi before. That brings us to now. I still cannot find the issue. It?s obviously flooding. During the extremely rough idle my vacuum reads between 4 and 0. I figured that would point to a vacuum leak but I can?t find any. My couplers are good, I smoke tested and sprayed brake cleaner. Nothing. I thought maybe weak spark as my plugs were fouled but I don?t understand how. My coilpacks are splitfire. Not even a year old. I already purchased a new CAS However that did nothing. I can provide more info if needed. Can someone help please?

S14rebuild · 07-26-2020, 11:13 AM

Did u do a boost leak test?

SilSanti · 07-26-2020, 12:05 PM

Quote:

Originally Posted by S14rebuild

Did u do a boost leak test?

I have done some soap and water tests in the past but not yet for this problem. How would that result in the issues I?m having?

S14rebuild · 07-26-2020, 12:16 PM

Boost/air leak will obvs cause the motor to run rich and stumble, fall on its face. Just a suggestion

SilSanti · 07-26-2020, 02:43 PM

Quote:

Originally Posted by S14rebuild

Boost/air leak will obvs cause the motor to run rich and stumble, fall on its face. Just a suggestion

I?ll give it a shot and get back to you. Thank you for the suggestion.

jr_ss · 07-27-2020, 08:04 PM

I would suggest you make a tester that goes on to the turbo inlet and let’s you pressurize the entire system.

SilSanti · 07-27-2020, 08:28 PM

Ok so quick update. I think I found the source of my problems. While taking a look at my injectors today I decided to spin the CAS. I noticed that 5 of the 6 injectors were actually firing. After checking all of the wire on my wiring harness I realized that some of the wires by where my ECU plugs in must be internally frayed. As I messed around with them the one injector fired with the rest. I’m looking into getting a new wiring harness and seeing if that solves my problems.

07-26-2020, 07:04 AM	#1
SilSanti Join Date: Apr 2019 Location: California Posts: 4 Trader Rating: (0) Feedback Score: 0 reviews	Rb25det neo running rich and idling rough Hey guys, I usually don?t make posts but I?m really scratching my head on this one and I can?t find any useful information anywhere. For context I drive an S13 with an RB25DET Neo. Recently I?ve decided to do rebuild and refresh the engine after tracking my car a couple times. About a month ago I had been experiencing lean issues where my car would hang between 13-15 AFR on WOT. Very unhealthy. I knew I couldn?t let it continue to run so lean. This is an issue that happened pretty suddenly. Previously I hadn?t had this issue, it just kind of happened. I changed my O2 sensor, both coolant sensors by the manifold water neck and cleaned my Maf. Did nothing for the AFRs. I got my ECU checked out by RS enthalpy. They tuned the ecu for my setup so I figured it wouldn?t hurt. It came back fine. I didn?t know what the issue was so I decided to let my car sit for a couple weeks until I decided to do my rebuild. About a week ago I started her up to take her to my buddies shop and she was chucking smoke. Tons of gas. I limped it to the street and began diagnostics. I couldn?t find an immediate issue, but it would not idle unless I kept it revved up. The only way for me to get it to my friends house was for me to drop the fuel pressure on my FPR to around 17psi. It was running at 43 psi before. That brings us to now. I still cannot find the issue. It?s obviously flooding. During the extremely rough idle my vacuum reads between 4 and 0. I figured that would point to a vacuum leak but I can?t find any. My couplers are good, I smoke tested and sprayed brake cleaner. Nothing. I thought maybe weak spark as my plugs were fouled but I don?t understand how. My coilpacks are splitfire. Not even a year old. I already purchased a new CAS However that did nothing. I can provide more info if needed. Can someone help please?

07-27-2020, 08:04 PM	#6
jr_ss Post Whore! Join Date: Dec 2005 Location: Pa Posts: 6,056 Trader Rating: (34) Feedback Score: 34 reviews	I would suggest you make a tester that goes on to the turbo inlet and let’s you pressurize the entire system. __________________ My SR20VET

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07-26-2020, 11:13 AM	#2
S14rebuild BANNED Join Date: May 2019 Location: Florida-FAIL Posts: 2,497 Trader Rating: (8) Feedback Score: 8 reviews	Did u do a boost leak test?

07-26-2020, 12:16 PM	#4
S14rebuild BANNED Join Date: May 2019 Location: Florida-FAIL Posts: 2,497 Trader Rating: (8) Feedback Score: 8 reviews	Boost/air leak will obvs cause the motor to run rich and stumble, fall on its face. Just a suggestion

07-27-2020, 08:28 PM	#7
SilSanti Join Date: Apr 2019 Location: California Posts: 4 Trader Rating: (0) Feedback Score: 0 reviews	Ok so quick update. I think I found the source of my problems. While taking a look at my injectors today I decided to spin the CAS. I noticed that 5 of the 6 injectors were actually firing. After checking all of the wire on my wiring harness I realized that some of the wires by where my ECU plugs in must be internally frayed. As I messed around with them the one injector fired with the rest. I’m looking into getting a new wiring harness and seeing if that solves my problems.