About to give up

[bcjjones]

STILL trying to diagnose this issue with my car dying with the a/c on. Haven't found any vacuum leaks, cleaned the EGR valve, the throttle body, put new gaskets and again checked all the vacuum lines. Its a non turbo so that made it easier. I also replaced the IAC valve due to the one being on the car was from a Mirage. I just bought the car. So does anyone else have any other suggestions? I also am curious, when I un bolt my IAC and had a buddy flip on and off the ignition, the IAC kinda just vibrated and didn't really move in or out. Is that normal? Doesn't seem like it to me. Should it actually move?
I really do appreciate all the help so far

 

[1995 gst]

if your car is lacking battery level turning on the ac will drain it and kill it. I know its a stretch but if your out of luck it doesnt hurt trying. Also if your idle is really bad to begin with from the bolt not being tightened it could also drop as it SHould drop your rpm when it turns on either way.

 

[schwabm]

What's is it that. Your car is doing when you turn a/c on

 

[bcjjones]

Battery is new, bought in January of this year. Alternator seems fine, keeps the car running with the battery disconnected. Idle is great otherwise. And by screw im guessing you mean the BISSS? It is adjusted properly to the best of my knowledge.

Sorry schawmb I didn't understand your question?

I forgot to mention it only does it when the car starts to warm up. It'll idle fine with the ac on while its cold but as soon as it starts to warm up (when the temp guage just barely moves up) is when it starts to die. I also forgot to mention that if I do give it just a little bit of gas, like hold the rpms around 800, it'll idle fine too even after warm. But if I rev it up it wants to die again unless I hold the rpms for a second. If that tells y'all anything?

 

[schwabm]

One thing u should never check a alternator by pulling the battery terminal off. It can fry the computer. So the car will idle cold but when it warms up it will not run right? Correct

 

[bcjjones]

Battery is new, bought in January of this year. Alternator seems fine, keeps the car running with the battery disconnected. Idle is great otherwise. And by screw im guessing you mean the BISSS? It is adjusted properly to the best of my knowledge.

Sorry schawmb I didn't understand your question?

I forgot to mention it only does it when the car starts to warm up. It'll idle fine with the ac on while its cold but as soon as it starts to warm up (when the temp guage just barely moves up) is when it starts to die. I also forgot to mention that if I do give it just a little bit of gas, like hold the rpms around 800, it'll idle fine too even after warm. But if I rev it up or while driving and just let off the gas wants to die again unless I hold the rpms up for a second. Then idles fine. It didn't do that when I first bought it. So I know the repairs I made helped a lot and im making progress because it would hardly idle at all before and fir sure not with the ac on.

Sorry I posted that twice. Yea while cold it will idle fine with the ac on or off. But when its warm it will only idle with the ac off

 

[schwabm]

How does the belt for a/c compressor look.

 

[bcjjones]

Battery is new, bought in January of this year. Alternator seems fine, keeps the car running with the battery disconnected. Idle is great otherwise. And by screw im guessing you mean the BISSS? It is adjusted properly to the best of my knowledge.

Sorry schawmb I didn't understand your question?

I forgot to mention it only does it when the car starts to warm up. It'll idle fine with the ac on while its cold but as soon as it starts to warm up (when the temp guage just barely moves up) is when it starts to die. I also forgot to mention that if I do give it just a little bit of gas, like hold the rpms around 800, it'll idle fine too even after warm. But if I rev it up it wants to die again unless I hold the rpms for a second. If that tells y'all anything?

 

[rlacasse1]

What rpm is your car idling at, and what is it suppose to idle at according to the factory manual?

Basically what I'm thinking is maybe when the car is cold and idling a little higher it is enough to run with the a/c on.

But as the car warms up and the idle drops then maybe it doesn't have enough balls to keep running.

So make sure that the idle is correct when the car is warm.

I don't know if that is it, or if that is possible, but it's kind of what I'm thinking may be causing the issue. Especially since you say you have to hold the gas pedal to hit 800 rpm.

 

[1995 gst]

what do you mean give it gas and hold it at 800? it should automaticly idle from 900-1.5k rpm without touching gas.

and it could be the battery cables. when you turn on the ac your cooling fans should turn on. itle drain the battery so if its new and all is well it will also drop ## rpms and if ## saying u have to hold to 800 you may need to turn up your idle.

 

[bcjjones]

Belt looks okay. But I haven't looked at it very hard. Could a bad belt cause this?

I haven't bought a manual yet. Read online though that between 750-1000 is normal. Mines right at 850-900. Without the ac on.

Also while im driving I can run the a/c and it'll run fine but I can feel a big drag on the motor. Kinda lugs it down. Then when I press the a/c button off it immediately gets rid of that lugged down feeling. But again if I press the a/c on the motor immediately lugs down.

When the cars warm it idles fine, without touching the gas it idles right around 900 or so. What I meant by having to hold the engines idle up is only if I rev up the engine with the a/c on and just let off the gas. Or while im driving and just let off the gas. If I don't feather the gas pedal a little bit the car will die. So if I hold the gas pedal around 800to or so after I let off the gas it will, again idle fine, until I rev it up or drive it and just let off the gas. Does that make sense?

I adjusted the BISSS with the car warm. And it idles fine when its warm, right at 900 or so until the ac is turned on. What I meant by having to hold the engines idle up is only if I rev up the engine with the a/c on and just let off the gas. Or while arcing and just let off the gas. It will just die if I don't hold the rpms up around 800to for a second after letting off the gas. But will idle fine after that until I again rev it up and let off the gas. Does that make sense?

Sorry my phone is screwing up on me

 

[schwabm]

Sounds like you might have a bad a/c compressor i would pull the belt off and see how hard it is to spin.

Nvm to that last post u said it only happens when you turn your a/c on. It could still be the compresser I would try and get some oil and run it in the system.

 

[knewblewkorvett]

what do you mean give it gas and hold it at 800? it should automaticly idle from 900-1.5k rpm without touching gas.

I thought our cars were supposed to idle around 750 rpm

I wish ya luck in finding the problem

 

[TheRealMRDyno]

The A/C load requires a little more throttle to idle.

The car runs a little rich, and a little higher at idle, when cold, so it can absorb the A/C load without stalling, but it can not once it is warmed up.

I am pretty sure you have one of two problems:

a) A/C system plugged up or compressor problem - too much load period, engine slows down at closed-throttle.

or

b) IAC problem - I had this myself, I think it is kind of common. When the A/C is on, the ECU gives the engine a little more throttle via the IAC to keep the RPM right. I think these cars also have a pressure sensor on the power steering that the ECU looks at for a similar purpose - if you turn the wheel a little bit to just load the PS pump, at a stop, then release the wheel, the RPM will bump up a little bit when you let the wheel go. I don't know what kind of IAC is on these cars, but a stepper or a servo should go to one end of its travel when you pull it off the car, but still connected, and turn on your A/C - the control logic (assuming a closed-loop type of control) will keep adjusting the IAC for more air, and never gets it to happen, so it runs all the way out on its travel. An open-loop (no feedback) controller will just move the IAC actuator by x-amount when you turn the A/C on, then back when you turn it off.

FYI, if it is a stepper type IAC actuator, a single bad phase in the motor, or the wiring, or the controller, can result in something just buzzing - the motor can not move correctly if the phases are not walked around the shaft in the correct sequence, and a missing phase definitely screws the sequencing up.

Hope this helps.

Joe

 

[bastarddsm]

Your ecu might have a burnt driver in it. Thats really common when and ISC dies. Usually it will the the driver transistor with it. Seeing that you had an oddball ISC, I'm sure the original one died. If it did and took a driver transistor with it, the new ISC won't work right and the car will have idle problems.

 

[WES_393]

+1 for IAC being bad. The ECU should be able to hold your idle pretty steady regardless of what's putting load on the engine.