R32 Gtr Aac Valve Refurbishment

[Les00x]

AAC Valve: Together with Air Regulator, manages cold and hot idle.

- Les Lothringer's Approach to opening up R32 GTR AAC Valve (Auxiliary Air Controller) - dismantling, cleaning, reassembling. Note: Nissan Workshop Manual cites this part as non-separable, non-serviceable.

- Reason: Poor idling, hot or cold - low, high, unstable due to sticking / seizing or not adjusting to correct position from ECU signal. Note: Many other reasons for poor idle, including faulty Air Regulator, Temperature Sensor, Throttle Plates mechanical stops, Throttle Valves Positioning Sensor position, Ignition Advance, also vacuum leaks in Hoses, Injectors, Collector / Inlet Manifold Gaskets, damaged silicon coating on throttle plates.

- Parts Source: If the internals are damaged, a used non-working AAC Valve may be useful.

- Duration: 1.5 hours one person.

- Difficulty Level: Easy once you know how, unless something goes wrong. Access to the right side of the engine is very tight.

- Disclaimer: This describes my approach. If you choose to follow it and make a mistake, remember - at all times, it's your fault. If you choose to follow it and get a different outcome, that's because you need to know more than what is described here. No responsibility for errors or omissions. Every car can be different. Torque settings as per Nissan WSM.

- Reference: Nissan R32 GTR Workshop Manual.

- Special Tools: Very Long Thin Nose Pliers (access is very tight), 1/4" socket drive tools, screwdriver (see photo) , Loctite, Dremel, Vise, Carby Cleaner, Silicon Gasket compound, Volt Meter.

- Repairing Small Springs: The small Spring inside the AAC CANNOT be improved / repaired. A COMMON FAULT is to stretch the Spring a little. This does not work and will result in a lowered Spring Rate - not a good outcome. If the parts inside are not corroded, just clean up. If corroded, acquire another AAC - 2nd hand or new.

- What Can Go Wrong: Unscrewing the Brass Plug is difficult. Standard flat blade screwdrivers will twist outwards and damage the soft brass metal. Refer picture for a screwdriver that may work, or make up a special tool.

Approach - Refer photos for method.

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Basically:

1. Remove #8 position fuse. Crank engine - run out gasoline.

2. Disconnect the two fuel supply / return fuel rubber hoses.

3. Unclip AAC electrical plug.

4. Unscrew 4 bolts attaching AAC to Air Chamber - underside of Collector.

5. Release spring circlip from Vacuum Hose onto the Collector - 3rd hose in from rear end.

6. Remove the AAC Valve.

7. Checks:

- Check movement of Plunger / Spring.

- Test resistance of Solenoid - should be 9-10 Ohms.

- Solenoid pin should move freely.

- Check applied voltage to AAC plug.

8. Unscrew Solenoid. Mount AAC in vise. Grind away plastic sealer covering the Brass Plug.

9. Use correct screwdriver to twist out Brass Plug. If this fails, make up special tool to twist out.

10. Remove Spring and Plunger - check for corrosion and damaged rubber parts on Plunger. If all OK, clean and re-assemble.

11. Twist in Brass Plug to take up free movement in Spring / Plunger assembly. Use Loctite on thread.

12. Attach Solenoid, Vacuum Hose and install back onto Air Chamber. Attach Vacuum Hose, fuel hoses, fuse.

13. Start engine, adjust Manual Air Bypass Screw to target hot idle RPM - 850 @ 20 degrees advance. If this screws all the way in and engine RPM does not drop, this suggests a vacuum leak. Refer above for possible causes, of which there are many.

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Torque Settings (ft.lbs): AAC Valve bolts = 5.

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[fib]

Thankyou for posting this. I partially cleaned my AAC awhile back but was unable to remove it from the hose. Will remove it completely next time it plays up again

[xfixiate]

QN: When you take up the free end play screwing in the brass lug, and you install the solenoid, the plunger is opened slightly by the solenoid. The plunger o the solenoid sticks out a little (probably 2 mm) . So when the solenoid is screwed back on, the valve is opened again.

Should I do up the screw until this doesnt happen (seems a long way in). Or should I do up the screw unil it "just" seals, and then fit the solenoid leaving the air valve open slightly..?

Any assistance appreciated.

BTW Effin amazing tutorial!

[SiR_RB]

^ can anyone answer this?

not totaly sure how tight to do the brass screw ?

also do these units build up with carbon/oil which affects idle ?

[xfixiate]

^ can anyone answer this?

not totaly sure how tight to do the brass screw ?

also do these units build up with carbon/oil which affects idle ?

Yes they build up with crap. Dismantle everything, use carbie cleaner.

Do up the big brass screw until there is no wobble in the valve. IE the spring has barely taken up the slack.

Do up the AAC adjust screw (smaller one) until it is about half way showing through the hole.

Dont forget to get it all good, then take the big brass screw back out, use medium/hard setting locktite, then do it up again, then put on a ring of locktite exterior as a seal,

[SiR_RB]

Sweet thanks for clearing that up,

Gonna take mine out and give it a clean later in the week

[SiR_RB]

I can't remove the brass plug, turned a tiny bit but now can't make it budge, don't wanna stuff the head either...

Any suggestions?

[SiR_RB]

QN: When you take up the free end play screwing in the brass lug, and you install the solenoid, the plunger is opened slightly by the solenoid. The plunger on the solenoid sticks out a little (probably 2 mm) . So when the solenoid is screwed back on, the valve is opened again.

Can anyone give advice on this please ? ^^

Should the spring be sealed against the body or should it be abit 'open' ??

[KyuubiGTR]

Awesome thread thanks