idle problems when my a/c is on................

[BYEBYE2U]

my car has H/C/I along with some other things but I don't know if this is causing part of the problem or not but,when i turn my a/c on it's fine as long as you're driving but when i stop the car idles like the TPS is bad and sometimes will drop down like it wants to stall.what could cause this?? could it be because i haven't had a tune done on my car yet or what? thanks

 

[kissrocksforever]

Mine does this too ^ hopfully someone will know. I've heard a Tune will help a lot though.

 

[BYEBYE2U]

i sure hope someone chimes in. it idles great besides this.

 

[det_riot]

Do base idle reset if you haven't already. Sticky for it is at the top of the 5.0 section.

 

[det_riot]

http://www.muscularmustangs.com/iac.php

 

[BYEBYE2U]

Do base idle reset if you haven't already. Sticky for it is at the top of the 5.0 section.

I have the foxbody/throttle body intake conversion done. If you mean the surging idle fix,that's an awesome guide but doesn't help me any.thanks though.

 

[det_riot]

Well if you're saying your tps is outta wack and your idle goes to shit, if you look through the link, it touches on resetting your idle. With the AC off, and AC ON. Because the computer doesn't recognize the load. It also talks about testing your TPS voltage to see if it is in spec. So do that to cehck that out. Then if that doesnt work try pulling codes. Then come back and let us know where that got you.

 

[BYEBYE2U]

Well if you're saying your tps is outta wack and your idle goes to shit, if you look through the link, it touches on resetting your idle. With the AC off, and AC ON. Because the computer doesn't recognize the load. It also talks about testing your TPS voltage to see if it is in spec. So do that to cehck that out. Then if that doesnt work try pulling codes. Then come back and let us know where that got you.

i will buddy,thanks again

 

[det_riot]

NP! Figured it's easiest to take out the easy variable firsts to see if it changes anything.

 

[1997GT4.6]

mine does the same and its driving me nuts! only mines a 4.6 dohc. people think i'm revving at them our getting ready to launch at the light lol

 

[BYEBYE2U]

mine does the same and its driving me nuts! only mines a 4.6 dohc. people think i'm revving at them our getting ready to launch at the light lol

your problem sounds like a bad TPS. mine don't do that all the time,it just idles a little jumpy with the A/C on when stopped.

 

[1997GT4.6]

your problem sounds like a bad TPS. mine don't do that all the time,it just idles a little jumpy with the A/C on when stopped.

Hmm I'll have to look into that. Thanks for the info! Well mine idles a little jumpy when I first turn the AC on. It does it for a few minutes. But the RPMs hang at 2k when I stop at a light than very slowly creep down. If I'm going forward with the AC on and the light changes to yellow before I get there, and I clutch in to get out of gear, my RPMs still linger around 2k which keeps the car car moving forwards even though it is not in gear. It's annoying. end rant /

 

[det_riot]

Hmm I'll have to look into that. Thanks for the info! Well mine idles a little jumpy when I first turn the AC on. It does it for a few minutes. But the RPMs hang at 2k when I stop at a light than very slowly creep down. If I'm going forward with the AC on and the light changes to yellow before I get there, and I clutch in to get out of gear, my RPMs still linger around 2k which keeps the car car moving forwards even though it is not in gear. It's annoying. end rant /

I'd try cleaning your IAC first, then MAF. then if it still does it, check the voltage on your tps

 

[CC'S95GT]

your problem sounds like a bad TPS. mine don't do that all the time,it just idles a little jumpy with the A/C on when stopped.

I agree with this as well. I had a similar issue and after I changed the TPS and TB the prob went away. Set you DVM (analog meter would be better) on OHM's and connect to the TPS and very slowly cycly the throttle blade while looking for any erradic jumps in the OHM reading.

 

[NJcobra94]

This idle surge is common I was h/c/I 5.0's... usually it's caused by the idle air control (iac ) on your intake. I has the same problem in my cobra... try taking the iac off and soaking it in carb cleaner or seafoam...also if depending on your setup try giving it some more or less timing

 

[1997GT4.6]

I'd try cleaning your IAC first, then MAF. then if it still does it, check the voltage on your tps

Yeah I've read those are the first and easiest things to check first. I need to check the voltage on my TPS though. What voltage should it read if it is good?

And actually I cleaned my IAC like 2 days after you reminded me of it, and idle improved dramatically no more bouncy needle. With the AC on, after cleaning it, the idle remained exactly the same as if the AC was off. Much improvement forsure. No more hanging RPMs. Well it worked great for a week so I know I need to replace it. And I am aware that cleaning it does not fix it, it has to be replaced. Which I will when summer school is out in 3 weeks. Still I want to check the TPS just to make me feel better lol.

I agree with this as well. I had a similar issue and after I changed the TPS and TB the prob went away. Set you DVM (analog meter would be better) on OHM's and connect to the TPS and very slowly cycly the throttle blade while looking for any erradic jumps in the OHM reading.

Thanks for the info on how to check the TPS. I need to do this but won't get the time until 3 weeks from now. I'm checking it for pete's sake though since I think the root of my problem is the IAC. Read my comment towards DetRiot thanks again for the info!

 

[CC'S95GT]

glad you got it running better.

 

[ttocs]

if you are tired of the motor revving to 1500-1700 rpms while you roll to a start, do a search for a IAC restrictor plate. Its easy to make out of some scrap aluminum and they work too.

 

[det_riot]

Yeah I've read those are the first and easiest things to check first. I need to check the voltage on my TPS though. What voltage should it read if it is good?

And actually I cleaned my IAC like 2 days after you reminded me of it, and idle improved dramatically no more bouncy needle. With the AC on, after cleaning it, the idle remained exactly the same as if the AC was off. Much improvement forsure. No more hanging RPMs. Well it worked great for a week so I know I need to replace it. And I am aware that cleaning it does not fix it, it has to be replaced. Which I will when summer school is out in 3 weeks. Still I want to check the TPS just to make me feel better lol.



Thanks for the info on how to check the TPS. I need to do this but won't get the time until 3 weeks from now. I'm checking it for pete's sake though since I think the root of my problem is the IAC. Read my comment towards DetRiot thanks again for the info!

No problem dude! Glad we could help!

 

[ttocs]

my tps was giving me issues last year. All kinds of crazy stuff from bad idle to suddenly dying with no warning while driving. It had 2-3 dead areas and I am sure the heat from the motor would effect it as well as it had different problems when it was warm then when it was cold.