How do you test IAA unit? car stalls when coming to stop(1991 240sx)

[vancouverbc]

How do you test IAA unit?
Modified by vancouverbc at 12:46 AM 4/27/2007

[NISTECH]

Ok not ignoring you here, just trying to determine what exactly your question is. You seem to be asking questions but then answering them with in the same post. I am a little confused.

[vancouverbc]

Im just reading the mitchel guide. I don't have any practical experience with mechanics. I'm thinking out loud and hoping to be corrected if i am wrong.

[NISTECH]

ok

I assume your working on your high idel problem? If so I really think you should look for a vaccum leak.

[vancouverbc]

I'm trying to trouble shoot stalling while idling . When I decelerate to a stop, the idle drops very low and sometimes stalls. It usually goes down to around 300/400 rpm and takes about a second to go back up to 700 rpm.(when it doesn't stall).

My idle was a constant 700 until I cleaned throttle and removed aiv so I think the high idle is just a result of previous owner playing with calibration screw on throttle linkage. I have a constand 650-700 rpm now that i adjusted calibration screw.

[JLonevia]

I'm trying to trouble shoot stalling while idling . When I decelerate to a stop, the idle drops very low and sometimes stalls. It usually goes down to around 300/400 rpm and takes about a second to go back up to 700 rpm.(when it doesn't stall).

My idle was a constant 700 until I cleaned throttle and removed aiv so I think the high idle is just a result of previous owner playing with calibration screw on throttle linkage. I have a constand 650-700 rpm now that i adjusted calibration screw.

Right when I press the breaks I feel loss of power, takes seconds to get back, sometimes even stall. sounds similar to mine. Hopefully its my IACV . When taking out the IACV do you have to take the intake? Seems hard to just unscrew it from there. I have a sr20det stock intake.

[nanamous]

I sometimes do stall at stop lights...going to try this and see if it fixes my stalling problem

thx for the pix very helpful

[vancouverbc]

After about 16 months with no stalling problems, I started having the problem of stalling at stop lights again. I tightened the large aac screw and that made it worse. I backed the screw off(loosened spring pressure) and the stalling is not occuring.

[MTX450]

AWESOME!! When I have a minute of non freezing weather, I will attempt to tackle this...I also notice something else besides the idle just dipping when slowing up to a light, while hitting the clutch. I also notice that when more and more electrical things are turned on (radio, fan, lights, and most noticable, the brake lights) the idle gets lower and lower. I went to a local autozone, and they did an alternator and battery test, and both showed fine results. Is it possible that the clogged AAC has something to do with it?

[rob808]

can this be applied to the SOHC engine also?im having the same idling/stalling problem as well.also when prior to installing the IAA unit back on do you have to seal again with epoxy?

[vancouverbc]

can this be applied to the SOHC engine also?im having the same idling/stalling problem as well.also when prior to installing the IAA unit back on do you have to seal again with epoxy?

the iacv is located in slightly difffernt place on sohc but it applies. No, you dont have to seal anything. it is just intake air. very simple to clean.

[rob808]

the iacv is located in slightly difffernt place on sohc but it applies. No, you dont have to seal anything. it is just intake air. very simple to clean.

thanks bc for your quick reply.i did this to my unit and not knowing there was a gasket there i had to wait till parents got home to make a trip to checkers to get some gasket maker.after installing everything back on and starting up,let it warm up,it idled perfectly,but i guess under load it still almost stalled on me.

i didnt get to take off the epoxy covering the large brass screw since i have no vice to hold the unit down while i try and chip away at the epoxy.any suggestions to take it off another way?thanks for the write up btw.learned something new since im not mechanically inclined

[donasmello]

I'm not quite sure what's going on here like the posts have been edited too much to tell what is going on. However, I have the same issue about stalling when coming to a stop under no load. I can keep it in gear and just down shift a certain way to get it to keep idle up but without doing that idle will drop below 500 rpm and sometimes stall. I have tried to mess with the idle air control valve and didn't really help to raise idle. From research I have also checked the fuel injectors and I have recently done a tune up so it's not spark plugs or anything like that. Was wondering if anyone could give me more detailed information about what's going on here or how to prevent stalling

[vancouverbc]

Have you taken the iacv apart. have you cleaned piston and spring?I have researched alot and have never read a comprehensive explanation of why idle drops when you stop or turn corners. I mess with the iacv big screw and seem to fix the problem that way. Not all years have the big screw to adjust spring tension for aac. after i recently changed my brake master cylinder i notice that idle jumps about 200 rppm when step on brake but there is a few second delay.

[donasmello]

haven't tried taking that apart. Wanted to avoid doing that because I think I have to take the manifold off to be able to get iacv off. Maybe I'll try it though

[vancouverbc]

I'll prolly write a tutorial on this but it is easy to get iacv off. just 4 10 mm bolts. some staples on the electrical connectors. you dont need to take manifold off. I dont think the 93 has the epoxy covered brass screw. I have the epoxy off my screw and it vibrates tighter for some reason and I start to stall again so i have to readjust . I guess i will tape it so it doesnt move.

[WhiteKnight]

Check the strainer below the fuel pump...Braking throws gasoline forward in the tank.

[vancouverbc]

Check the strainer below the fuel pump...Braking throws gasoline forward in the tank.

How would the strainer have any affect on this situation?

[WhiteKnight]

It affects fuel pressure when it gets clogged

[WhiteKnight]

A mechanic told me today that it could be a vacuum leak from the brake booster--if dropping idle when braking.

[WhiteKnight]

I replaced the IACV and the vacuum hose and everything works fine now.