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Can You Diagnose This Problem?

=premo=

By =premo=,
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BH_SLO32 Proficient

BH_SLO32

Posted
Posted (edited)
Thanks to Grigor and YLD-CHLD for helping me find the ecu pins, will have a look at them and other suggestions this weekend, if I can get it sorted then it will be in for another tune on Wednesday.

Pin 104 is FPCM output 1.

Pin 106 is FPCM output 2.

Pin 18 is fuel pump relay.

Does anyone know where the FPCM is on a Gts-t or know where the wiring for it runs?

The operation of the FPCM in the GTST is controlled by the RB20ECU. From memory it earths pin 104 which only happens when the engine is cold. Once warm it switches off. It is not load related. The FPCM circuit runs in parallel with the fuel pump resistor and allows are greater current draw (better pump performance) when the engine is cold. Not sure if this is emissions related or simply to allow more fuel when cold. The GTR ECU seems to control the operation of the FPCM in the opposite fashion (ie. battery voltage when cold and earthed when warm). I will confirm.

With your setup I would therefore expect that the FPCM circuit to switch on ONCE WARM as opposed to switching off when warm. Therefore, I now don't think this is your problem. I think your problem might be related to load and would suggest looking at the Map sensor wiring.

Edited by BH_SLO32
=premo= Mentor

=premo=

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The operation of the FPCM in the GTST is controlled by the RB20ECU. From memory it earths pin 104 which only happens when the engine is cold. Once warm it switches off. It is not load related. The FPCM circuit runs in parallel with the fuel pump resistor and allows are greater current draw (better pump performance) when the engine is cold. Not sure if this is emissions related or simply to allow more fuel when cold. The GTR ECU seems to control the operation of the FPCM in the opposite fashion (ie. battery voltage when cold and earthed when warm). I will confirm.

With your setup I would therefore expect that the FPCM circuit to switch on ONCE WARM as opposed to switching off when warm. Therefore, I now don't think this is your problem. I think your problem might be related to load and would suggest looking at the Map sensor wiring.

Hmmm, could still be that the FPCM wires have different pins on the Gts-t car looms plugs to the GTR engine loom plugs so once it gets to the ecu its connecting to the wrong ecu pin and then once warm its causing a short.

Dont think it could be map sensor's as they plug into the side of the Power FC so unless it is faulty the wiring couldn't be wrong.

acsplit Veteran

acsplit

Posted
Posted

just put a relay on the fuel pump and use pin 18 to trigger the relay (bypassing the other crap) btw the trigger wire pulls to ground.

just make sure with the resistor you have the power wire feeding into the main power feed wire on the resistor pack and not one of the wires you would call and output

=premo= Mentor

=premo=

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just put a relay on the fuel pump and use pin 18 to trigger the relay (bypassing the other crap) btw the trigger wire pulls to ground.

just make sure with the resistor you have the power wire feeding into the main power feed wire on the resistor pack and not one of the wires you would call and output

That would help to keep the fuel pump going but the Power FC would still shut off if there is a short or are you suggesting to cut all the other wires relating to the fuel pump at the ECU plug??

I take it you mean the ballaster resistor pack for the injector's, I have the power in connected to the white wire and the injectors connected to the six blue wires.

BH_SLO32 Proficient

BH_SLO32

Posted
Posted (edited)
Hmmm, could still be that the FPCM wires have different pins on the Gts-t car looms plugs to the GTR engine loom plugs so once it gets to the ecu its connecting to the wrong ecu pin and then once warm its causing a short.

Dont think it could be map sensor's as they plug into the side of the Power FC so unless it is faulty the wiring couldn't be wrong.

In the RB20 loom, pin 104 is a green wire with white stripe on the 12pin plug (the largest of the 3 in-cabin plugs). This plug only has 5 wires, 2 wires to the wiper motor plug, the 2 wires to the fuel pump resistor and pin104 wire.

This might help if you are looking for plug location of pin104 and 106 in the GTR loom.

Cheers

Edited by BH_SLO32
femno Grand Master

femno

Posted
Posted
Wheel sensor plug will be on the other side. That small one is for the Air con if that loom wraps around to the front.

I would be looking at the fuel pump control circuit first, something maybe earthing there when it tries to turn on.

No.

Theres a wheel sensor on each wheel on a GTR.

acsplit Veteran

acsplit

Posted
Posted
Hmmm, could still be that the FPCM wires have different pins on the Gts-t car looms plugs to the GTR engine loom plugs so once it gets to the ecu its connecting to the wrong ecu pin and then once warm its causing a short.

Dont think it could be map sensor's as they plug into the side of the Power FC so unless it is faulty the wiring couldn't be wrong.

Yep cut the fuel pump wire close to the ecu, then run a fresh wire down to a relay in the boot then you know the fuel pump controller is not playing games.

=premo= Mentor

=premo=

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Yep cut the fuel pump wire close to the ecu, then run a fresh wire down to a relay in the boot then you know the fuel pump controller is not playing games.

Had a play with it yesterday and found that the fuel pump relay and plug wiring seems to be fine. I located the FPCM and tested the wires to make sure the right pins from the ecu plug were reaching the FPCM, they were all correct but I noticed on the wiring diagrams that the fuel pump is still wired in if the FPCM is removed so I left it unplugged and also earthed the fuel pump so its only controlled with the relay (pin 18) now.

I also went over the car and ran negative wires to all of the existing earthing spots which greatly reduced the problem with the gauges. They still read slightly lower when the headlight's are on but nowhere near as bad as before.

Took it for a drive and it seems the problem is gone but I wont be sure until the tune gets finished as its risky accelerating past where the problem was.

Fingers crossed its all fixed. Will let you know how it all goes.

BH_SLO32 Proficient

BH_SLO32

Posted
Posted
Had a play with it yesterday and found that the fuel pump relay and plug wiring seems to be fine. I located the FPCM and tested the wires to make sure the right pins from the ecu plug were reaching the FPCM, they were all correct but I noticed on the wiring diagrams that the fuel pump is still wired in if the FPCM is removed so I left it unplugged and also earthed the fuel pump so its only controlled with the relay (pin 18) now.

I also went over the car and ran negative wires to all of the existing earthing spots which greatly reduced the problem with the gauges. They still read slightly lower when the headlight's are on but nowhere near as bad as before.

Took it for a drive and it seems the problem is gone but I wont be sure until the tune gets finished as its risky accelerating past where the problem was.

Fingers crossed its all fixed. Will let you know how it all goes.

Earthing the fuel pump near the fuel pump will remove the FPCM and the resistor from the fuel pump circuit. At least now it will simplify the wiring as you said. I cannot state how important it is to have good earths. Fingers crossed you have fixed the problem.

=premo= Mentor

=premo=

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Problem fixed but oil too thin so it hasn't been tuned fully but once I've changed the oil it can be driven hard on 230rwkw's safely. Once my wallet has recovered a bit I'll get the cam gears adjusted and tune finished.

Anyone know where to get 10L of Redline 15-50 cheap?

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