R33 rb26dett won't rev pass 5200

[r32gts]

Alright. So I got a s13 that has a rb26 in it. It has a single turbo. Nistune. Greddy intake. And front mount. I'm having a issues with it not revving pass 5200 when it's under a load. Acts like a rev limiter. It'll free rev past 5200 fine. But not under a load. It's has a 7lbs spring in the wastegate. And new spark plugs I gap at .25. The maf sensors are also inline. If anyone has any ideas, lemme know. I checked grounds. On everything. I did manage to get one good pull randomly and it continued doing what it's doing now. Thanks!

[Skym]

Sounds like the safety rev limiter (fuel cut). Stock ECU can engage that rev limiter for two reasons that I know of:

1.) One or both of the knock sensors on intake side of engine are faulty (or a wiring / plug problem).

2.) There's no speed input (0km/h) into ECU from dash (usually a wiring problem).

Also check for intake airleaks just before MAF's, as can engage the boost cut (usually before 5200rpm).

[r32gts]

I knoe that the speed sensor isn't hooked up. It has a electronic sensor on the trans, no idea how to hook it up to the r32 ecu
Where are the knock sensors located? I'm gonna take the dash apart and fenders and chase and check every wire on that car.

I know after this all started happening. I was getting on it one day and it happened to go passed 5200 and I got to feel the motor. Then after that, it continued to do what it's doing. Is there anyway to tune out the fuel cut just out of curiosity?

[Skym]

I think you need a custom speedo cable if have a mechanical dash and RB25DET transmission (talk to a local speedo specialist). There might some companies online that sell engine conversions parts.

Knock sensors are under intake plenum, near top of cylinders. Should be one knock sensor front and one knock sensor rear of engine (I think a pain to get to on a RB26).

It's sometimes the wiring falling out of the plugs if someone has pulled on the wiring to plugs instead of the plug when unplugging sensor (happens with TPS, MAF, etc). Usually people rewire the car and make sure they use quality connectors / plugs, tape around the wires into connectors / plugs for extra grip for the connectors / plugs to prevent the wires from being pulled out of the connectors / plugs.

With Nistune for stock ECU you can adjust the safety fuel cut (whatever rpm you want to set it at and another setting for that rev limiter, which I gather relates to the knock settings).

Nistune modernises the stock ECU, so stock ECU can be retuned / reflashed via the Consult plug under dash on drivers side of car (grey plug next to fuse box under the dash). Just like most new cars, but done in real time. If have R33 RB26, can use R32 RB26 ECU with Nistune, R32 RB26 o2 sensors (different to R33 RB26 o2 sensors).

Also you'll need the consult cable, laptop, tuning software, wideband (if tuning ECU), usual tuning tools like knock headphones, etc (visit local Nistune tuner, there's a few in the states).

[r32gts]

Yep it has all that. It's tuned right now. It's just having that issue. I think it's reading knock but I dont remember. I'll look into it. Yea the motor is in a s13. I'm gonna check all the wiring in it. Seeing how it ran good that one time, maybe something was making contact for it to work then lost contact.