Calling all rb20 experts please help!!!

Discuss the RB20, RB25 and RB26 series engines.
Jamz
Posts: 5
Joined: Sun Oct 07, 2018 4:59 pm
Car: 1989 s13 hatch with rb20det

Calling all rb20 experts please help!!!

Postby Jamz » Tue Jul 09, 2019 7:25 pm

Alright I have a silvertop rb20det in my 89 s13 hatch, previous owner bolted the motor in but never got it running. Only thing I’ve yet to replace is the ebay looking turbo manifold and turbo fitted by the previous owner. Ecu throws code 54 (no auto trans input) It’s a 5 speed so im unsure if the motor was originally auto or if its just the ecu. I will attach a couple videos at the bottom to better display the issue.

The bad: Car used to idle and drive perfect but one day out of the blue it started up idling at 3,000rpm, I fixed this by fitting a new TPS (idle switch went out) but the car now does not want to idle. I’m seeing 12.3 AFR Idling at 1,100 but sometimes rpm will drop towards 650 and the wideband shows it going more lean corresponding with rpm (14.5:1 at 800rpm 15:1 at 650 then it will bog around 400rpm and show - - - on my aem Wideband.) Car drives somewhat fine out of boost I cruise around 15.5-16.5 at 10-0 vacuum but car will go lean and hesitate if I do not keep throttle above 10 vacuum (but boost gauge shows 20vac at idle & I smoked it and didnt see any leaks)
Now if I get into boost it will peg at 10.8 for one second then go to 11.8 then start to lean out to 13.0-14.0 around 5-6k rpm(I build 10psi at 4,500). The tune is rated for 300hp at 13psi but I’ve turned it down to 7psi and it still goes lean.

Sorry for writing you guys a book but I’ve run out of money to just simply throw at this car and I’m hoping someone might be able to steer me in the right direction. I’ve been in contact with martin at RS and he’s sent me an updated chip that I installed and it seemed to make no difference so I’m thinking its a mechanical or sensor problem

Mods include:
T3/t4 68mm (looks like ebay?) turbo
550cc deatschwerks
255lph walbro
Wiring specialties Rb20 “OEM” Style engine harness
Isr FPR (43psi w/o vac)
Fmic (2.5in piping)
ISR z32 MAF
TPS from Nissan (set at .48)
Direct fuel pump relay wiring mod
Stock r32 ECU with RS-Enthalpy tune through Enjuku
Cold start valve deleted
No BOV
Timing belt & idlers and set timing at 15 degrees

I haven’t replaced:
Knock sensors
CAS
AAC
o2 sensor (mine is placed about 2ft down the exhaust and stock is right on the downpipe, does this matter?)


Jamz
Posts: 5
Joined: Sun Oct 07, 2018 4:59 pm
Car: 1989 s13 hatch with rb20det

Re: Calling all rb20 experts please help!!!

Postby Jamz » Tue Jul 09, 2019 7:38 pm

Car at idle https://youtu.be/NdP9dhFRvn0
Car while at WOT https://youtu.be/kvzcuIxvYio
Forgot to mention it goes 2.5ish inch downpipe to 3 inch exhaust with one resonator and a muffler with 4 inch opening

Yellow4g63
Posts: 3717
Joined: Mon Jan 20, 2003 6:07 pm
Car: 95 RB20 240, 91 NX2000 VE power, 95 Stock 240sx
Contact:

Re: Calling all rb20 experts please help!!!

Postby Yellow4g63 » Wed Jul 10, 2019 11:52 pm

could be a few things, Like a bad maf sensor or the wiring to the maf sensor. Coolant temp sensor giving the ecu a false reading. Having nissan datascan would help you here because you could monitor the sensors from a laptop.

Jamz
Posts: 5
Joined: Sun Oct 07, 2018 4:59 pm
Car: 1989 s13 hatch with rb20det

Re: Calling all rb20 experts please help!!!

Postby Jamz » Thu Jul 11, 2019 1:36 am

its a brand new ISR z32 maf maybe it’d like an oem z32 maf better? I just got the harness off enjuku and it even came with the z32 pigtail prewired in so I’d hope the wiring was quality :gotme & Ok I’ll do that and share what I see thank you!

jacob005
Posts: 11
Joined: Wed Nov 06, 2019 2:50 pm
Car: R32 Skyline GTS-4

Re: Calling all rb20 experts please help!!!

Postby jacob005 » Thu Jul 16, 2020 11:27 pm

I agree that you need to hook it up to a laptop and see what the sensors are telling you.

If the ECU is from an automatic car, it will want to idle at 20 deg BTDC. But if its chipped that is probably changed so that might not matter.


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