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Rb25det Neo Idles But Struggles To Accelerate

Neoman1995

By Neoman1995,
in General Maintenance

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Neoman1995 Rookie

Neoman1995

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I Have converted my gq nissan patrol to a c34 series 2 auto stagea motor, it fires up and idles like a dream but as soon as any throttle is applied it coughs and splutters and barely gains any rpm

I believe it could have something to do with the throttle control unit not being used so any wiring guru's that could shed some light on what could be happening

Kinks Grand Master

Kinks

Posted
Posted

factory MAP sensor installed? Plumbed in BEFORE the throttle body? (ie between the intercooler and the throttle body)

The factory Neo ECU uses pre-TB MAP for transient response. If you don't have it connected up right it will be a dog on blipping the throttle but if you blip and hold for about 3 seconds then it will sort itself out and rev freely again (ie, it switches back to the airflow meter).

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Neoman1995 Rookie

Neoman1995

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I had another read of the engine manaul and found that if the tps is open/shorted across the power circuit, the motor will use the base idle tune and not inject any extra fuel when accelerating, my exact symptoms, so I checked and boom, the earth was not connected, so now I'm thinking that the ecu's tps code needs to be cleared as I've tried to start it with the tps hooked up properly and the same thing happens,

My new question is about the scan tool, it appears nissan consult protocol is used with the c34, will I be able to use a newer OBDII scan tool to clear this/any codes?

KiwiRS4T Grand Master

KiwiRS4T

Posted
Posted

I had another read of the engine manaul and found that if the tps is open/shorted across the power circuit, the motor will use the base idle tune and not inject any extra fuel when accelerating, my exact symptoms, so I checked and boom, the earth was not connected, so now I'm thinking that the ecu's tps code needs to be cleared as I've tried to start it with the tps hooked up properly and the same thing happens,

My new question is about the scan tool, it appears nissan consult protocol is used with the c34, will I be able to use a newer OBDII scan tool to clear this/any codes?

No only the proper consult will work.

Have you tried resetting the ecu by disconnecting the battery for a while?

Neoman1995 Rookie

Neoman1995

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Ok so the scan tool diddnt support the ecu protocol:'( so I had to wire pin 17 ( malfunction indicator lamp) to the patrols glow plug fault light and use the paper lip method,

It pulled codes 12(MAF signal wire), 21(ignition switch signal), 26 (turbo pressure sensor signal wire) and 44(TCS/ABS communication line)

I worked out the issue with the maf sensor and ignition signal so now the computer is only throwing codes 26 and 44 now after a clearing or fault codes and a restart, and engine is revving more happily but still coughing

So now the question is about the remaining fault codes 26 and 44,

If code 44 isn't going to throw the check engine light (as according to the service manaul) should I not worry about this fault code?, or should I fake the ecu input of around 2.0volts to the communication line (pin 79) to trick the ecu into thinking everything's all good?

Code 26 pulls the check engine light, is it worth getting the turbo pressure sensor and connecting it up or just fake the inputs too?

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