THIS LOW RPM ENGINE STALLING SAGA POSSIBLY SORTED

[BLUEGTR]

I have the same problem with my R33 and I was just wondering were I would fine the earth for the fuel pump

[Guest Sim32]

hey i just got my car, for a week it was fine, ran great.

but now the thing seem to do exactly what u guys have been describing. like stalling when u slow down at a lights..well not stalling just dipping real low, 100 + rpm then then just before cutting out the engine seems to regather itsself and go up again. But it fluctuates heaps, and just doesnt sit on a nice idle speed like it did. The car has stalled on me about 3 times..

starting to annoy me..

What is this ACC valve u speak of? and where is it? and how can u clean it??

also, do u have any pics of earthing the fuel pump?

cheers.

[MegaGTS4]

Sim32,

For RB20-25 motor

The AAC valve (Auxilliary Air Control Valve) is located at the back of the plenum chamber (inlet manifold) there is a maroon electrical plug (brittle) and a hose which need to be removed first then there is four ten millimeter bolts that also need to be removed before the whole assembly can be (careful if you want to use the orignal gasket again) removed from the car.

then there is two screws that hold the solenoid on, once this is removed the remaining assembly can be cleaned by useing carby cleaner (I used kero and a compressor to dry and clear any blockages) also make sure that the spring moves(smooth) and the valve works.

Reassemble in reverse order with a bit of sensor safe silicon with the original gasket(or you could make another one it depends on weather the gasket comes off in one piece) hope this helps!

It really is quite easy!

Stuttering might be spark plugs, have them gaped to 0.8mm this helps (platinum/iridium plugs also are a good choice for turbocharged engines)

MEGA

[Guest Sim32]

thanks man..thats really helpful

althought the car hasnt done it since...i still will check it out. yeah i was thinking spark plugs as well. whats best brand to put in rb20?

cheers.

[browny]

Nizmo32_Josh

Why did you not just replace what appears to be a faulty relay?

There would not be a relay there if there wasnt meant to be one.

[Nizmo32_Josh]

they relay just shuts off the fuel pump once the pump sends a "pressure reached" signal . bypassing this just keeps the fuel pump goin with ing. and not stopping from 100% till car is shut off.

[browny]

hmm thats not the way I understand it works on an RB20.....

The ECU just looks to switch the power to the fuel pump via the relay so that:

*When the ignition is turned on, the pump is powered for 5 sec

*When the engine is cranking/running the pump is powered

I think that the ecu uses a signal from the AFM to determine when the engine is cranking/running. This means that in the event of an accident where the engine stops, the ecu will turn the fuel pump off - a safety feature.

The fuel pump control modulator also acts like a relay to control the voltage (and hence current) across the fuel pump by switching a resistor in and out. The resistor is located between the pump and earth and the switching is controlled by a signal from the ECU.

So if you earth the pump straight to the chassis it will always receive full voltage and therefore run at full capacity whenever the ecu wants the it to run. (You might as well also remove the control modulator and resistor because this effectively short circuits their operation)

If you short the relay then the modulator should still control the pump in the same way as before but you have just removed the functionality of the fuel cut safety feature.

I have any of this wrong someone please correct me.

[Mase]

Im having similar problems with my rb20det silvia. A mechanic friend adjusted an idle thing on the back of the manifold. It has improved but occasionally the idle drops and raises dramatically and when changing down gears sometimes it stalls. I have new iridium plugs, new vl turbo fuel pump. Do you think that maybe i need a regulator at all? This is really bugging me.

[Nizmo32_Josh]

well after doing what brownie has told me is *wrong* i have not had a problem at all and im the envy of my mates with 32/33's as all have bad idles.

[Mase]

so u just cleaned up the earth on the fuel pump???

[Nizmo32_Josh]

no left the earth on the fuel pump alone and bypassed a relay

[browny]

well after doing what brownie has told me is *wrong* i have not had a problem at all and im the envy of my mates with 32/33's as all have bad idles.

Thats only the way I understand the system operates.

If you want me to, I can post up a schematic of the fuel system and you can explain how it works.

[Nizmo32_Josh]

ok sounds good

[Guest VuDuDoc]

Originally posted by Nizmo32_Josh

no left the earth on the fuel pump alone and bypassed a relay

can you explain which spades are by passed? i look at the top and see the numbering on the relay but what is by passed?

and could it be that the pump is stuck in somewhat of an idle where pump output doesnt vary with accelertation/deceleration?

[browny]

Pump wiring:

[Guest VuDuDoc]

ok now i have another question........ does the sylvia also posses a fuel control module?

i have a great suspicion on these modules having problems.

[Nizmo32_Josh]

My fpcm has 4 wires going into it thou

[browny]

I think the ground is one.

[Nizmo32_Josh]

ok sorry didnt see that on the diagram

[Spook's_Skyline]

when i got my skyline, it demonstrated this exact problem;

didnt do nuthin, but it went away;