rickyellow zee Posted March 19, 2013 Share Posted March 19, 2013 I have an L28ET swap in my 78 280z. Completeley stock. It is missing the VCM which controlls the EGR and the AAC. As a result the idle is low and its hard to start( not enough air at startup?). How are you guys with similar set ups controlling the idle? Ive tried a number of things like adjusting the air bypass screw on the air flow meter and idle screw on the throttle body but all Im getting is a hunting idle(revs up and down). Could I use a vacume from the intake mani to controll the AAC. At idle the vacume would open the AAC allowing more air in and at open throttle it would close due to boost. Would this work?Any help would be much appreaciated. Thanks Rick Quote Link to comment Share on other sites More sharing options...
Tony D Posted March 19, 2013 Share Posted March 19, 2013 If your AAC is late model, there will be a screw on it, you can apply vacuum till you get the speed you want then screw it in to raise the idle to that point permanently. Z31's have this type of valve, and some L28ET's that had the valve replaced later on in life. Alternately, on one application, we did as you inquired about and ported the AAC to manifold vacuum, when you drop-throttle the valve opens and raises your idle. It worked so well we didn't use the other AAC we had with the screw. It idles just fine like that. Quote Link to comment Share on other sites More sharing options...
rickyellow zee Posted March 19, 2013 Author Share Posted March 19, 2013 If your AAC is late model, there will be a screw on it, you can apply vacuum till you get the speed you want then screw it in to raise the idle to that point permanently. Z31's have this type of valve, and some L28ET's that had the valve replaced later on in life. Alternately, on one application, we did as you inquired about and ported the AAC to manifold vacuum, when you drop-throttle the valve opens and raises your idle. It worked so well we didn't use the other AAC we had with the screw. It idles just fine like that. My aac is the one without the adjustment screw. Okay so I will use the intake vacume to controll the AAC. Do I need to use the air regulator along with the aac?(throttle body to air regulator to AAC) or just go from the throttle port located on top of the throttlebody to the AAC? I have an 82 air regulator with the coolant fittings on the side but its not installed. My thorttlebody is an 78 with the cold start valve(not used), idle screw and throttle bypass on top. Currently the throttle bypass hose is capped. Thanks again. Rick. Quote Link to comment Share on other sites More sharing options...
Tony D Posted March 20, 2013 Share Posted March 20, 2013 We hooked Ian's into the nearest port on the plenum we could screw a fitting into, or where it existed... There may have been one straight forward of the valve. You are combining two items, the AAR (fast idle) isn't needed. In fact, now that you HAPPEN to mention you are using a 78 TB, you don't need the AAC, either! Adjust your idle speed using the idle speed screw on your 78 TB, you don't need the pneumatic crap! I used an SX T/B, and used the 82 NA idle speed screw on mine and it works FINE. the auto compensation anti-stall was more emissions than required to not stall.the idle speed bypass works just fine all on it's own. Quote Link to comment Share on other sites More sharing options...
rickyellow zee Posted March 20, 2013 Author Share Posted March 20, 2013 So cap the AAC and the port on throttlebody and just use the idle screw to set idle. I will try this and reply with results. Nothing worse than following a thread and the original poster never gets back with results. Thanks. Quote Link to comment Share on other sites More sharing options...
Tony D Posted March 30, 2013 Share Posted March 30, 2013 Yes, it is... Quote Link to comment Share on other sites More sharing options...
rickyellow zee Posted April 1, 2013 Author Share Posted April 1, 2013 Well it still idles like poo. I hooked it up as stock as possible but without the VCM. It goes throttlebody port to air regulator, regulator to AAC. AAC vacume hooked up to manifold. When idle the AAC opens raising the idle, under boost aac closes. air regulator also bumps up idle when cold. It idles best this way so far. Still not perfect though and I strive to have this car running as good as possible. Will not settle for anything else. On a related note...I am not getting voltage to the air regulator now. I checked continuity on the black wire which goes to the ECU and I get continuity. The green wire goes to the fuel relay which I no works cause the car gets fuel. Why no volatge to the air regulator? Makes no sense at all. As it is the air regulator stays open till it gets heated from the intake mani. Any suggestions? Thanks for all your help thus far. Never give up! Quote Link to comment Share on other sites More sharing options...
Tony D Posted April 7, 2013 Share Posted April 7, 2013 (edited) AAR is powered when fuel pump is running. The AAC is redundant, and only a source of problems. The Stock Euro Turbos used a simple idle air bypass exactly the same as the N/A's did. What the hell happened to "cap the AAC"? You seem intent on listening to your own drum, so good luck with that. A single source of idle air that is fixed is all you need. If it idles like crap, do a tuneup and go back to basics. I have no idea why you would put an N/A TB on a Turbo Manifold...but you didn't get a good result. Look at and understand stock turbo air routes in the FSM, you ARE NOT routing it like a turbo should be routed. That hose to the AAR is NEVER under boost! On to better things. Edited April 7, 2013 by Tony D Quote Link to comment Share on other sites More sharing options...
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