Rb25det going into limp mode - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

SethG12 · 09-27-2014, 04:33 PM

Ok I swapped my r34 rb25det neo into my s13 about 3 months ago. Wiring specialties harness everything was legit on the motor, put it in drive it for a good month to 2 months and it ran very very good. I don't get on it very much since it's my daily driver and it's a really clean shell that I don't want to smash up. We'll anyways lately my car started acting funny is start it up and it would sound like it's cammed for about a min then knew it warms up a little bit it'll be fine. But then once I get on the highway after about 20 min once it fully warms up to it's top operating temp it'll start to decelerate all the way down to 3200 (what my un calibrated tac says) then it won't let me rev any higher than that 3200 mark and if I do it'll sound like a "2 step" the car has a walbro 255 with stock fuel pressure regulators and wiring specialties harness and fmic. Everything else is stock. I've tried cleaning the maf with maf cleaner, unplugged the o2 and drove it and it still did it, unplugged the maf and it putts it into limp mode at a little higher rpm. My s13 doesn't have a data link cable to church check engine light, And my ecu doesn't have the indicator light or dial on it.

kouki-gymkhana · 09-28-2014, 05:49 AM

It could be a number of things causing your problem. It's likely an ignition, fuel, or MAF problem. Weak or failing coils? Check your ignition coil harness for any damage or broken insulation. Did you replace the fuel filter when you swapped the motor? The fuel pump may also not be getting a constant 12v supply so try hard wiring it. I know you said you cleaned the MAF but RB25 MAFs are notoriously finicky! See if you can temporarily swap it with a known good MAF and see if the problem goes away.

Good luck! It would also be better to post this in the technical section under the RB sub section.

SethG12 · 09-28-2014, 09:00 AM

I'm changing my spark plugs today cuz they looked pretty bad a couple months ago when I put the motor in i just never went and got new ones till today. So it might not be getting good enough spark. The fuel filter was changed 3 months ago when I swapped it, and the fuel pump is a walbro 255. I didn't check the voltage yet. And it has the pink label maf e60, or n60 I forget (from the 94-99 maxima) same as neo. How do I check my coolant temp sensor? On the engine? And ok I'll post it there

09-27-2014, 04:33 PM	#1
SethG12 Leaky Injector Join Date: Oct 2013 Location: Dayton, OH Age: 27 Posts: 65 Trader Rating: (1) Feedback Score: 1 reviews	Rb25det going into limp mode Ok I swapped my r34 rb25det neo into my s13 about 3 months ago. Wiring specialties harness everything was legit on the motor, put it in drive it for a good month to 2 months and it ran very very good. I don't get on it very much since it's my daily driver and it's a really clean shell that I don't want to smash up. We'll anyways lately my car started acting funny is start it up and it would sound like it's cammed for about a min then knew it warms up a little bit it'll be fine. But then once I get on the highway after about 20 min once it fully warms up to it's top operating temp it'll start to decelerate all the way down to 3200 (what my un calibrated tac says) then it won't let me rev any higher than that 3200 mark and if I do it'll sound like a "2 step" the car has a walbro 255 with stock fuel pressure regulators and wiring specialties harness and fmic. Everything else is stock. I've tried cleaning the maf with maf cleaner, unplugged the o2 and drove it and it still did it, unplugged the maf and it putts it into limp mode at a little higher rpm. My s13 doesn't have a data link cable to church check engine light, And my ecu doesn't have the indicator light or dial on it.

09-28-2014, 05:49 AM	#2
kouki-gymkhana Zilvia Member Join Date: May 2003 Location: Boston & So. FL Posts: 246 Trader Rating: (2) Feedback Score: 2 reviews	It could be a number of things causing your problem. It's likely an ignition, fuel, or MAF problem. Weak or failing coils? Check your ignition coil harness for any damage or broken insulation. Did you replace the fuel filter when you swapped the motor? The fuel pump may also not be getting a constant 12v supply so try hard wiring it. I know you said you cleaned the MAF but RB25 MAFs are notoriously finicky! See if you can temporarily swap it with a known good MAF and see if the problem goes away. Good luck! It would also be better to post this in the technical section under the RB sub section. __________________ The atypical S-chassis enthusiast*

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09-28-2014, 09:00 AM	#3
SethG12 Leaky Injector Join Date: Oct 2013 Location: Dayton, OH Age: 27 Posts: 65 Trader Rating: (1) Feedback Score: 1 reviews	I'm changing my spark plugs today cuz they looked pretty bad a couple months ago when I put the motor in i just never went and got new ones till today. So it might not be getting good enough spark. The fuel filter was changed 3 months ago when I swapped it, and the fuel pump is a walbro 255. I didn't check the voltage yet. And it has the pink label maf e60, or n60 I forget (from the 94-99 maxima) same as neo. How do I check my coolant temp sensor? On the engine? And ok I'll post it there