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There is a plug for your ECCS circuit near your coolant air bleed valve on the head towards the front of the car clipped near the fuel rail. That plug connects your knock sensors and other sensors connected on that harness to the main engine harness and fuse box area. Check this plug is connected properly as I know of a car that had very similar symptoms when this plug came loose.

So I got to the AAC and it was nasty. I am reading conflicting things online. Some people say the AAC controls the idle and the IAC just does electrical load balance and others are saying the opposite.

Also I found a million write ups on removing the AAC and cleaning it but nobody seems to ever clean their IACV (or at least they dont post about it).

Anyone know for sure?

I still dont really see how im going to get the IACV off without removing the plenum. Hopefully I dont have to.

If the IACV (the one i havent taken off yet) just assists the cold start idle I am not opposed to blocking it off completely as I dont need it to be perfect on cold start. This is not a daily street car by any means.

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waiting on new gasket to arrive. In the meantime i have seen some talk of a fuel pump ground mod but noone seems to explain ecactly what wire it is that need to go to chassis.

Heres a pic.

Anyone know what wire need to be grounded to bypass the resistor? I ohmed out the white and the black/yellowstriped wire and get about 30k to ground on both.

I am lost. What one is the one you run directly to gound?

IMG_20160404_215801863_zps74yshdhh.jpg

The naming of the 2 valves is the biggest problem. Nissan are not completely consistent across all their engines and years and various people call one valve one name and the other valve the other name, whilst other people are completely the opposite and some don't know about it at all but talk as if they do.

All you need to clean to make sure it's working is the one that has the stepper motor and is controlled by the ECU. That is the one that is used by the ECU to hit the idle speed target.

what ecu are you using? do you still use the AFMS?

seems like the broken afm solder issue I had. I know you said that you have replaced the MAFs but what condition are the maf plugs in?

I have both an APEXI PowerFC and the stock ECU, same issue no matter what one im using. I deleted the air regulator valve and it did not correct the issue. (my thinking was that if it was not closing once up to temp it would be alowwing too much air.)

I also tried unplugging the AAC while it was running and there was no change at all. That leads me to believe that even though its now clean I dont think its operating properly. Unlpugging this should cause some sort of change if it was doing anything at all.

I did put 12V to the solenoid on the AAC and it did actuate but im not sure if once it gets hot it stops functioning. (thats exactly the case with the relay for my driver power window. When left out in the sun the window wont go up or down but when cool it works fine)

My MAFS are bran new from nissan and unplugging either one of them causes a huge change in the way the engine runs. I think im good with the AFMS.

  • Like 1

code 55 means "All OK"

I have not tested the TPS, Ill start looking in to that.

I was thinking the same thing about the gauge so I am ordering a fuel pressure gauge to do some more testing.

I will keep updating this as a go because this problem WILL get solved. And then after I plan on making a good write up on all the steps to test everything related.

  • Like 1

I had this same issue in my 32 gtr in 2006. Scary changing down gears to corner as power steering and brakes fail at the instant. Prior to resolving this issue the engine failed due to oil pump letting go causing oil starvation and the big end bearing let go. I had the engine rebuilt and the problem was gone when I got my gtr back.

Good luck.

  • Like 1

The fuel pressure gauge should be here tomorrow. In the meantime I tested the TPS and I have .41 volts closed with the hard idle switch ON, then only 3.8 volts wide open & hard idle switch off.

Hard idle switch seems to be working fine but shouldn't the TPS be reading 5V when fully open?

  • 4 months later...

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