hoohaa Posted June 27, 2007 Share Posted June 27, 2007 Can we use the stock Nissan Idle Air Adjusting unit (IAA) and the Idle Air Control Valve (IACV) with MSII? The 95 pathfinder FSM says this about the IACV: "A bimetal, heater and rotary shutter are built into the IACV-air regulator. When the bimetal temperature is low, the air bypass port opens. As the engine starts and electric current flows through a heater, the bimetal begins to turn the shutter to close the bypass port. The air passage remains closed until the engine stops and the bimetal temperature drops." The 95 pathfinder FSM says this about the IAA: "The IAA unit is made up of the IACV-AAC valve and idle adjusting screw. It receives a signal from the ECM and controls the idle speed at the preset value." The 95 pathfinder FSM says this about the IACV-AAC (Aux. Air Control): "The ECM actuates the IACV-AAC valve by an ON/OFF pulse. The longer then ON duty is left on, the larger the amount of air that will flow through the IACV-AAC valve." Sounds to me like the IACV-AAC includes an independent electric warmup function and also a PWM controlled valve. Could the MSII control this valve? Quote Link to comment Share on other sites More sharing options...
mtcookson Posted June 28, 2007 Share Posted June 28, 2007 Might try the MS forum: http://forums.hybridz.org/forumdisplay.php?f=88 Quote Link to comment Share on other sites More sharing options...
nismopu Posted June 28, 2007 Share Posted June 28, 2007 then they will suggest msefi.com and then you will be totally lost as they will be no help either, lol. I know of one guy who runs it on a vg and far as I know you dont need it. You will control idle mostly by pulse width of the injectors. I believe you can get it to work I just dont know of anyone who has. peace. Quote Link to comment Share on other sites More sharing options...
Administrators BRAAP Posted June 28, 2007 Administrators Share Posted June 28, 2007 then they will suggest msefi.com and then you will be totally lost as they will be no help either, lol. I know of one guy who runs it on a vg and far as I know you dont need it. You will control idle mostly by pulse width of the injectors. I believe you can get it to work I just dont know of anyone who has. peace. Uh, That there is some very bad advice, (unless you were meaning something else that you didn’t specify in your post). Controlling engine idle speed by means of altering injector pulse width on gasoiline engines is totally and completely the WRONG approach and should never be an option, EVER! There are so many other band-aid ways around getting an acceptable idle speed. In 99% of all gasoline EFI applications, Idle speed is controlled by adjusting the amount AIR the engine is breathing at idle by some form of air valve. Then injector pulse widths are altered/adjusted to obtain the desired Air Fuel Ratio ONLY. Any and all adjustments to the pulse width of the fuel injectors should ONLY be done to modify the air fuel ratio to a desired point. NEVER use injector pulse widths to control RPM. Sorry for being so harsh. It is this sort of misinformation that a newbie not knowing any better, might implement and worst case, end up with extensive and expensive damage to his/here engine. Most likely they’ll just end up with fouled plugs and major drivability issues due to the fouled plugs and they wont know how to diagnose the casue, yet rectify it. Quote Link to comment Share on other sites More sharing options...
Administrators RTz Posted June 29, 2007 Administrators Share Posted June 29, 2007 Idle speed is a function of the correct volume of air... matched by the proper amount of fuel and timing. A 'fuel only' method will buy you nothin but trouble. Quote Link to comment Share on other sites More sharing options...
hoohaa Posted June 29, 2007 Author Share Posted June 29, 2007 Well I have not found much more info on the WD21 IACV-AAC that I've read in the FSM, so I guess when I get to that point in the install I will give it a try. It sounds to me like there are two different systems functioning in the same package. A small heater that runs off of ignition current and functions independently from the engine's idle or temperature, and an actual idle air valve to increase idle under high load, whether from the AC, the power steering, or something else. Of course the heated valve is no problem, that will function on its own. However, this idle valve sounds to me like it's controlled by the ECU with PWM. I am going to try to get it running. Quote Link to comment Share on other sites More sharing options...
nismopu Posted July 2, 2007 Share Posted July 2, 2007 i know you guys know your efi stuff but all the vehicles i have worked with involving MS didnt have any idle devices hooked up and idled fine. So, yes your correct to get a decent idle your afr has to be set correctly at idle and you do that by adjusting the PWM. I wasn t calling it a band aid method but last i checked trying to run a 10:1 afr at idle would cause plug fouling and hardly any dile at all. The timing of injectors air intake and engine timing all play into affect of the idle, I understand all this. Im sorry if it wasnt conveyed correctly. peace. Quote Link to comment Share on other sites More sharing options...
Administrators BRAAP Posted July 2, 2007 Administrators Share Posted July 2, 2007 You are correct in that an engine can function without an idle speed controller, whether it be a stepper motor type or the bimetal strip type. For a street engine, you will be compromising either cold running idle speed or have a high engine idle speed when the engine is warm if you eliminate the cold idle speed compensation. My personal L-28 Z aka BRAAP, with the stock EFI, ran without the factory idle speed compensation, (the air flow regulator). I then used the set screw that adjusts the throttle plate “closed” position to a point the engine would idle where I wanted, reset the TPS, and that was it. Now in doing this I made a major compromise. That was when the engine was full warm, idle speed was between 1000 and 1100 RPM. When the engine was full cold on a cold winter day, say 32 degrees, upon initial start up, the engine would barley idle on its own at 500-600 RPM. Fuel injector pulse width was optimized for AFR only. Another example is my L-28 Mega squirt EFI race car. I did the same exact thing, no idle air controller. Difference there was I utilized a later 280-ZX remote idle speed adjuster attached to the bottom of the manifold instead of just adjusting the throttle valve “closed” position. I set the warm idle speed where I wanted it, and that was that. I had to baby sit the gas pedal on cold start for a couple minutes till the engine warmed up to the point it would maintain its own idle, small compromise for race car. In both scenarios, I only adjusted the fuel injector pulse width for a stable idle. With Mega squirt on the race car, I used our LM-1 and dialed in a 14:1 AFR. Here is the BRAAP car… Here is the Race car… Quote Link to comment Share on other sites More sharing options...
nismopu Posted July 2, 2007 Share Posted July 2, 2007 I know both your cars very well and I have even talked to you a few times at the canby shows. I made it saturday this year but not sunday when most of the z car guys showed up. so, I have no clue if you were there this year. Anyway, its good to see your jumping around more here on hybrid helping people with your z car knowledge. peace. Quote Link to comment Share on other sites More sharing options...
ZR8ED Posted July 2, 2007 Share Posted July 2, 2007 "A bimetal, heater and rotary shutter are built into the IACV-air regulator. When the bimetal temperature is low, the air bypass port opens. As the engine starts and electric current flows through a heater, the bimetal begins to turn the shutter to close the bypass port. The air passage remains closed until the engine stops and the bimetal temperature drops." Located on the passengerside of the intake manifold. Yes megasquirt can control this unit. It mearly has to give it power. It needs ignition power only. Once a certain amount of time has passed (I don't know how long it takes) The heater inside warms up and closes the air valve. This remains closed until the vehicle is turned off AND cools down. It is simply a valve that allows extra air during cold startup and idle. The idle valve (located on the drivers side of the intake manifold) is another story. I have always had problems with mine since the install and mods. I have unhooked all the wires to it. I then blocked off 98% of the air flow. (98 is a guess) I had to block off most of the air, because with no power to the unit, it sits wide open letting all kinds of air in. It has a couple of spring loaded actuators that bypass air, and move with the pulses in the intake manifold. Those acuators keep the idle stable. I don't fully understand that unit. The car will not idle properly without it. The idle will surge without the actuators (I removed them as a test) I can't really offer much else, other than with my megasquirt, I am going to use it to control my warmup bypass, but i will continue to use my butchered idle control valve. BTW why are you using a pathfinder FSM? are you using a pathfinder vg30? Scott. Quote Link to comment Share on other sites More sharing options...
hoohaa Posted July 3, 2007 Author Share Posted July 3, 2007 "A bimetal, heater and rotary shutter are built into the IACV-air regulator. When the bimetal temperature is low, the air bypass port opens. As the engine starts and electric current flows through a heater, the bimetal begins to turn the shutter to close the bypass port. The air passage remains closed until the engine stops and the bimetal temperature drops." Located on the passengerside of the intake manifold. Yes megasquirt can control this unit. It mearly has to give it power. It needs ignition power only. Once a certain amount of time has passed (I don't know how long it takes) The heater inside warms up and closes the air valve. This remains closed until the vehicle is turned off AND cools down. It is simply a valve that allows extra air during cold startup and idle. The idle valve (located on the drivers side of the intake manifold) is another story. I have always had problems with mine since the install and mods. I have unhooked all the wires to it. I then blocked off 98% of the air flow. (98 is a guess) I had to block off most of the air, because with no power to the unit, it sits wide open letting all kinds of air in. It has a couple of spring loaded actuators that bypass air, and move with the pulses in the intake manifold. Those acuators keep the idle stable. I don't fully understand that unit. The car will not idle properly without it. The idle will surge without the actuators (I removed them as a test) I can't really offer much else, other than with my megasquirt, I am going to use it to control my warmup bypass, but i will continue to use my butchered idle control valve. BTW why are you using a pathfinder FSM? are you using a pathfinder vg30? Scott. I'm running a Pathfinder manifold on a Pathfinder VG30E. I bumped into some good info on the PWM valve on some Maxima sites. I will update this thread when I determine which sites are most salient. Quote Link to comment Share on other sites More sharing options...
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