I NEED some IACV help

[locoluna825]

Hey guys, on my 90 sohc. I have been having starting issues lately. I recently cleaned the IACV valve and ever since The car usually kicks up to about 1500-1600 RPMS at startup. And once in a while the idle will go a little loopy on start up. Just lately, its done this a couple times now. When I start it, when its cold and been sititng, it dies shortly after. I Just noticed today while looking under the hood for something loose.





When the key is in ON position, before its actualy running. There is a buzzing noise coming from the AAC Valve. I unplugged it and it went away. plugged it back in and it started buzzing again. I started the car up with it unplugged. Car started up around 500 rpms and ildes like s***. didnt die acts like it wants to though, Doesnt always die on cold start up. But the car usually starts up around 1500-1600 rpms. I need some help here... TPS?? Tempt sensor?? BAd AAC valve???

[locoluna825]

So i went ahead and tried following some thread on how to adjust the TPS sensor. I couldnt get the numbers the guy who wrote the thread was getting. The resistance the thread said you should be getting on the TPS sensor was in between 2-10 depending on if the throttle was closed to all the way open. Im getting like 3-8k ohms..... so i dont know if that means mine is bad or what... I tested another one i had in the garage and i got the same readings. Also it says you need to get .45 - .55v from 3 pin harness plugs. But there are two 3 pin harness plugs and i couldnt get a reading like that anywhere... only voltage i could find was like 13-14v going to the tps sensor.

So i went ahead and started adjusting it anyway. i disconnected the tps sensor liek you do when you time the car and pulled it back a just a bit. and plugged the harness back in. Now the car idles around 2000 rpms and doest stop. wont go down. unless i force it down with the clutch. But it will still slowly work its way back to 2000rpms. I had to unplug the AAC valve to make it stop. with that unplugged it at least idles at 700 but without it that car rpms will just drop from the powersteering and and deaccelaration.

Cant get it to stop i need help adjusting this TPS sensor...

[locoluna825]

today I tried swaping out the AAC valve of the IACV with another i had. I was broken so it didnt even work. I put the old one back in and it was still buzzing. I foudn out the reson tis buzzing is becuase when the key is on the ecu sends out a signal fro the plunger in it to push. and the resistance cuased by the spring in the IACV cuases the AACV to buzz. I its deffinitly working. dont know if the buzzing is a sign its going bad though... Ill have to pick up another AACV. Can anyone help me adjust the TPS sensor?

[vancouverbc]

buzz prob means it is defective or not enough power

1991-1993-240sx-tps-adjusting-testing-t469111.html

[locoluna825]

Thanks for that.^^ I already knew how to turn it. But the problem I was having was testing the right wires, so that the voltage was right. Anyways... I took another shot at adjusting the TPS sensor. And I got somehwere this time.


Found the wire that makes the .45-.5 voltage. and i got down to exactly .45


Also did a resistance test afterwards. The sticky said it should inbetween 2-10 and as you can see im its sorta around there... I tested another Tps i have in the garage and i get nearly the same numbers as the one thats on mine.

Throtle closed.


Throtle open.

[locoluna825]

spent on and off today driving and checking more stuff. I found that the Air Regulator Valve had no Resistance and the spare i had in the garage did, very little less than k. The harness connection going to the Airregulator has like almost no voltage going to it. VERY little. Does anyone know how much supposed to be there???
So i spent like 2 hours becuase its PITA trying to swap them out. also replaced my Temp sensor. And rechecked the TPS sensor voltage. Swapped out the ECU for my spare And nothing. it does the same thing... I can unplug the AAC valve and it will stop. or pinch of the hose going to it. Idles SOMEWHAT normally when you do that. Im goonna leave it till after the weekend. guess im gonna change the TPS sensor with my spare or start gutting the wiring harness. Then im outa ideas after that... anyone got any..? NOBODY ?

[locoluna825]

Summary

So ive checked everything on the IAC system and replaced what needed to be using the FSM. I also checked and adjusted the TPS, and it should be good now. nothing wrong with it.

I found this check list in the FSM about stuff that controls your idle. Heres what it looks like.



I checked off the things that are Obviously not effecting my idle.

Not the engine temp sensor, Just replaced it.
Not the air conditioning switch, Dont have ac.
Not the powersteering, that only works when you turn the wheels
Not the vehicle speed sensor, cars not moving.

-I see that it says the battery will effect it. Would a weak battery cuase the Ecu to make the AACV kick on? to charge the battery up? I know mine is a bit weak. But does it actually do that?

-The idle switch is the TPS sensor? NO? if it is i guess i could check it off.

-Im not to sure about the inhibitor switch since i dont have one anymore. My car is a Auto to manual conversion. I just connected the wires from the harness coming from the inhibitor swtich.

-Ignition switch... I dun know
carnk angle postion switch... I dont know... No code showing up for that.

[vancouverbc]

disconnect negative battery terminal for 5 minutes to reset computer. you have to do that when you have been adjusting the tps. u should get a consult cable because it shows you what the tps is doing and it tells you what the computer is telling the aac to do. the buzzing is a problem. get a new iacv. if it is not the iacv , you have a short in those wires going to iacv.
air regulator bumps up idle when car is cold. if you plug the rubber hose at front of engine that goes to air reg and iacv, the car should stall. if no stall, you have extra air getting in from somewhere. legit air comes in through the 3 holes in the iacv ie ficd for a/c, aac, and fix hole you adjust with idle screw. you also get air through the throttle butterfly valve.(200rpm)

anyway, plug the hoses and plug throttle and maf etc to determine where the air is coming from. make sure the air reg. closes. its not magic only a few places the air can come in unless there is a leak. IE plug the throttle how much does idle drop etc

[locoluna825]

Yea ive been pinching the hose that goes to the Air regulator and IACV and the car DOES stall. I spayed the whole engine down with starting fluid while I had another watch to see if the idle moved. and nothing did. so i think there isnt a vacum leak.
Do you know how much voltage is supposed to be coming to the AAC valve when the key position is on??? I cant seem to find it anywhere in the fsm. But its some like over 10.?? volts.
Also on the possibility that it might be the battery voltage I left it charging all night long. so that it will be at full voltage.

[locoluna825]

Wish i could buy a consult cable but they dont make them for single cams...

Drove the car around just got back. Its back to what it was doing before i touched it.

At start up. ilde goes to 1100 rpms. then slowly works it way to 1400-1500 RPMS.

Take off. Driving down the road. seems perfectly normal.

Clutch in. Idle will drop to 1400-1500 rpms and stay until you completly stop. then the idle will slowly go down to 1100 rpms.

If you hold the brake with the clutch out. until the engine RPMS are below 1300 RPMs, Then push the clutch in. The RPMS will drop to 1100.
After you come to a complete stop. the RPMs will go from 1100 and work its way up to 1400-1500 again.

Its better than yesterday, at least its not constanly 1800 anymore. But its still buggy.

[vancouverbc]

hook up the battery and ground directly to the iacv aac and see if it buzzes. otherwise you probably have a short. plug the hose right at the iacv when car warm . if car stalls,you know air regulator is closed as it should be.

be careful with the multimeter, if one of the probes touches the neg and postitive of a sensor, that will kill the relevant circuit in computer.ie short circuit. same with unplugging sensors etc when power on.

everything i know is written in the iacv tutorial. and forgotten it now.

[locoluna825]

Sorry, ive been gone camping. So yea I took the AAC off and pluged it straight to the battery before. It didnt make a buzzing noise whit it out of the IACV. But if you put pressure on the pluger with your finger, it would make buzzing noises. So probably whit it all assembled and the srping from inside the IACV pushing up against it, it was making it buzz with power on. Im gonna go hunting for spares parts in the junk yard soon. Ive been ripping to much s*** off my spare motor XD.

Started up the car when i got back. and its acting totally different.
Turned it on. idle came up to 1000 and slowly warmed up to 1300 then came back down to 1000 and was idling normaly at 1000. I Think It needs some adjustment with the idle speed. I messed with it earlier when I was running the car with the AAC unplugged.