My idle's choppy. whenever i'm slowing down and stopped at a red light it revs between 600-1300 rpms over and over again.

It only happens when i have the A/C on, and it happens more when it's hot out, like over 100 degrees outside.

I've swapped the MAF sensor, and we've tried leaning out the idle with tuning, but we can't seem to make it go away. Idle is currently set at 950.

It didn't start happening until after my intake install, which is why I thought it was the MAF, but i replaced it and nothing.

Please help diagnose this problem!!!

 

Mine does the same thing, almost to the point where it feels like the engine is about to shut off. Like yours, its always with the AC on and very hot out. I do have both a HE and water/meth.

 

i have no cooling mods. it's good to know now that cooling mods don't help with this particular problem though. Thanks for the info!

Still need help with diagnosis though, please!!!

 

Mine and my friends did it. We both have 2006 models SS/Sc. There was a newer flash avaliable at the dealership that fixed the issue though (it was 100% computer related). I don't know if the 2007's have the same fix though.

It was not specific to the AC on or off though. It would happen every time we would come to a stop/slow down.

 

Nope no fix for '07 for that issue. It does it WORSE with the GM tune on there. I just can't seem to make it go 100% away.

And his car has an ultra sensitive knock sensor that says he has ungodly knock on 1-2 shift (like 35-45*) LOL there is not even that much timing!

 

Mine will only do that if i leave it in gear to long when im stopping
like if I forget that its in gear and its about to stall I push the clutch in to
save it the rpms will flucuate for a few seconds then stops.

 

i think that is normal..... when it is about to stall the engine is struggling.... if you clutch then suddenly it becomes free and reves higher then sittles out.

 

I'm gonna do some tests with transmission braking, and when to do it, because it does seem to have something to do with when i put the clutch in while i'm slowing down. Like, if i brake from 40 without the clutch in at all, it doesn't do it as much, but if i throw it in 2nd and trasmission brake, once it gets down to like 2000-1500 rpms i put in the clutch and it does it more often than not.

Any more info is definatly appreciated!!!

 

^^^^

This is a good guy to listen to about issues with our car. All of his posts are well informed.

However, another guy i know just bought an 07 a few days ago. If I can get a hold of him I don't think his car does it even with AC on.... I will find out for sure though tonight maybe. If it doesn't then there might be a new flash for the 07.

Also are you running premium gas?

 

my 07 does the same exact thing. it cut off on me once. it only does it with the A/C on like your's does. i hate it.

 

it doesn't do it when stock, so it must be something that the mods do to it... either the tune, or the intake, or something screws it up. Like i said, it didn't do it until after the intake install. eventually, i might try putting the stock box back on and see if it fixes the problem...

 

The engine adds fuel to raise the rpms, then when you take off the load by pressing the clutch in the rpms jump from the extra fuel. Only at low speeds in gear.

 

on my 07, I have a stage II install and the problem with the bouncing idle didn't happen while stock. It seems weird but has never stalled out. So it should just be a programming issue with the tune as far as mine is concerned.

 

Its and A/C compressor issue.

The HHRs have been having that a lot or locking up compeatly.

If you can get it to do it regularly take it to the dealer and have them look at it. Most likely they'll just replace the compressor.

The 07's LS/LT/SS-NA's have an ECU update to keep the Compressor for comming on at "high rpm" quote the GM Service Information.

 

i noticed that if i don't transmission brake, it doesn't do it at all.

 

when slowing down, pop it in neutral. let out on the clutch. this will help 200% on the idle issue. mine does it. i get funny looks from people with honda's when i do it next to them

 

yeah, but it doesn't help your clutch. I guess i'll just transmission brake when the a/c's off...

 

Just transmission brake all the time, and live with it for now. We may just have to wait for GM to come up with a service update. Cause the blasted thing won't tune out.

 

anyone have a problem with kn intakes making ur car choppy when shifting and then accelerating?

 

No, those are usually the better ones.

 

i've had this ac idle issue with my car since it was new and compleetly stock. now I have the stage two and it is even worse than before. it is very annoying.

 

'07s run so rich compared to previous years, I think they compensated somehow with the A/C on which makes it worse.

 

i have noticed something

with the a/c on. the afr jumps from 10.2 up to 16.6 during this "idle surge". it does this at a rather rapid rate. like gm knows about it, knew about it with the reflashes. and did nothing about it.

unlock the damn ecm and i'll fix it!

 

A little off topic....but for the '07s running so rich would that produce the "puff of smoke" that I get out the back of the car under mid to high acceleration??

 

depends on the color of the smoke...... I get a black smoke under wot from running rich. My brothers 05 also does this.