# rough idle / surge with a/c on ?



## aarons1k (May 23, 2008)

hi everyone just bought a used 05 GTO less than a month ago and just noticed when i turn the a/c on the idle surges from 1000 to 1500 drops and then climbs , only when i am at a stop with the clutch in?????The car is mostly stock it has headers and full exhaust , and i was told it was programmed, not sure what type or anything i didnt get the programmer..... Its weird if i turn the a/c off , it stops turn it on and it starts .. any help would be appreciated!
thx aaron


----------



## Rukee (Feb 8, 2007)

The A/C compressor is engaging and disengaging, I`d say it`s normal.


----------



## aarons1k (May 23, 2008)

So it is normal for the idle to surge like that ? It will surge till you take off and start driving and then when you come to a stop it starts up again? Since the car is programmed , that would not have anything to do with it , would it? I wish i knew what type of programmer is had!!!! I know the cooling fan runs 24-7 and it has a 160 degree therm stat in it ....


----------



## Red Bearded Goat (Mar 19, 2007)

Rukee said:


> The A/C compressor is engaging and disengaging, I`d say it`s normal.


Along with the radiator cooling fans that should start while stopped... they could be causing voltage to dip and resultant idle surge to compensate....


----------



## aarons1k (May 23, 2008)

The cooling fans run 24-7? I dont think that is normal is it? How would they be set to run all the time? It has a 160 therm?


----------



## Red Bearded Goat (Mar 19, 2007)

aarons1k said:


> The cooling fans run 24-7? I dont think that is normal is it? How would they be set to run all the time? It has a 160 therm?


That is not normal for them to run like that unless maybe your in the desert... having a 160 deg thermostat and tune, sounds like whoever did the programming set the fans to run like that...


----------



## aarons1k (May 23, 2008)

okay , the car was orginally from TX so that may have something to do with it..


----------



## 69bossnine (Aug 9, 2007)

You shouldn't have that noticable of a surge, the a/c cycling or the fans shouldn't have your idle wagging 1,000 rpms... 

I'd say your tune is a bit whacky, or your mass-air sensor is giving goofy readings (it's not uncommon). 

When I installed my K&N cold-air kit, my mass air sensor didn't like being relocated, and was all over the place. My car would just flat-conk-out... My tuner programmed the car to run on speed-density, and it's been a dream-boat ever since.

But I digress... I'd be looking to get a fresh dyno-tune, and find out whether your m.a. sensor is faulty...


----------



## aarons1k (May 23, 2008)

hey guys , as some of you know i just bought a 05 GTO and have been experiencing some problems with it when i turn the A/c on , the idle surges and it makes it run super rich. My dad brought home the Tech 2 and we found that the engine load shows a minimum of 20% all the time , cooling fans are at 99% all the time also. When i bought it from the second owner he said it was programmed not sure with what or knew nothing about it. My dad and i pulled some Hardware and Software number of the computer , and i was thinking some one that has a 05 with a programmer , superchip , diablo , etc can maybe check theres and see if the number are similar? so here it is

Hardware number 12596003

Software number 12596734

92179530

12596763

92179530

92179522

92179528

92179523

92179532

92179526

So i guess if i cant find the brand of programmer , i will have to clear the aftermarket program off and load the stock GM one. I also have another guestion for your guys that have your gto's programmed is it possible to turn Cat. sensors off or something , cause i have full exhaust no cats and no check engine light???

I would appreciate any help i could get , i'm stuck

Aaron


----------



## Vbp6us (May 6, 2008)

Anyone else experiencing this?


----------



## aarons1k (May 23, 2008)

Vbp6us said:


> Anyone else experiencing this?


I found the problem a few months ago before i put the gto in storage , it had a custom tune put in it before i got it , " the car was from Texas" Some how who ever did it , they messed it all up! And they locked the ecm! i took it to a local shop in IL , specializing in GTO Speedinc and they couldnt even get into it , lucky my dad works for Chevy and got me a new ecm and sent mine back and it runs fine! It was doing some funny Sh*t !!! The tune was making it shift hard , a/c problems , and running super super rich!! Just naming a few! I plan on taking it back to Speed this spring to have the skip shift and o2 censors turned off. kinda of wherry to get a tune again.....


----------



## AaronGough (Nov 20, 2008)

I actually had a similar problem like that recently. I was sitting in traffic with the car idling and when i turned on the ac it went to running like crap. I turned the ac off but left the fans blowing and when i would turn it off it would idle right after a couple of seconds but then when i turned it back on it would run bad again. Now going down the highway i turned it on and it didn't seem to be effecting it so I don't know what the deal was. The only difference is that it didn't surge like the way yours did Aaron. It acted like the bearings were going out in the compressor clutch.


----------



## aarons1k (May 23, 2008)

yeah mine surged it would raise and lower 700 rpms at least! u couldnt notice it as much when you were driving , but as soon as you stop and have the a/c on it would do it. I wonder if something is bad with you compressor???


----------



## Copasetic (Oct 20, 2008)

I'm pretty sure you can turn the CAT sensors on and off with a programmer and resetting it to the stock GM settings would probably be best if all you have is headers and exhaust.


----------



## AaronGough (Nov 20, 2008)

Ok well, weirdest thing. I got home from offshore the other day and drove my car and what do you know, it has no ac problem now. I gotta get it in to the dealer for oilchange anyways, guess i could break out the warranty on this deal. who knows maybe it was nothing after all, but then again maybe it is the compressor and its going slowly. I hope not, I got a dyno day coming up in march and I don't want my car to be in the shop.


----------

