My car has an issue with the RPMs dropping to 500 or lower and bouncing back up and down before finding an idle when I push in the clutch after accelerating with the a/c running. Sometimes the car stalls out completely. Does anyone have some insight on what I should start with checking?

 

I get that some times too.

 

People are gonna say dirty TB/MAF.
I've cleaned that ****, and I still get a bouncy idle sometimes, so I dunno.
#4bangerprobs

 

Hmmm...the bouncing around wouldnt bother me as much if it didnt stall out every once in a while. So this is a normal problem???

 

Check the usual first. Spark plugs, fuel filter, air filter, maf, tb, etc. maybe get a log if u can thru hpt of when it happens. Might be a drop in fuel pressure, might be something else

 

What injectors are you on? Tuned?
60s are known for having a rough idle

Running a cold air intake?
You could be getting water in the intake, before I invested in a hydroshield, car ran like **** every time it rained.. nearly hydro locked at one point... Also caused rough idle issues, and other issues at wot

 

42# injectors on the GM stage 2 tune. No cold air kit and the issue arises in dry weather just the same as wet.

 

same exact problem. car will stall usually when im on the third speed or above for AC. on the highway im fine, but stop and go traffic is where i have to feather the throttle to try and keep it around 1k rpm coming to the light.

i've also tried what was mentioned above, clean the MAF and TB but that didn't change much of anything.

 

I get this at times when at lights or in stop and go traffice and my cars stock minus intake.. I think it happened before the intake too. Could have sworn I read a thread abck then about all kinds of people having this issue and that it was "normal"

 

Normal. I had this SAME EXCAT Issue with my 2007 s/c and on my LNF its not an Issue, Seems like its just on the LSJ's. But as stated earlier most guys are gonna say clean your MAF/TB and sometimes that does do the trick, But NOT all the time....I just dealt with it, lol

 

How annoying....to think that its just the strain of the accesory drive and SC on the puny little 2.0L. Makes me appreciate my LS2 "fun car". LOL

 

mine doesnt do it (im an lnf though) but if i have the AC on for a while my fuel trims get skewed quite a bit.

 

As other people have stated, clean out your thottle body, I just had this issue with my LSJ and ever since I cleaned it out it hasnt given me any more problems. Idles nice and smooth with AC on.

 

i get this exact problem a lot, sometimes it stalls and yea just runs like dogpiss when the ac's on. its embarassing haha. i've cleaned my TB and i'm on 60#'s.

someone else was having a pretty similar issue and turned out to be a fuel filter. i might swap it just to be sure.otherwise i forget what others have told me before on this

 

mine does this but only when the ac is off lol. I've tried cleaning out the throttle body which the first time helped because it was real dirty. I've changed plugs cleaned maf n stuff and it still does it. Only died down on me twice so not sure what it can be. I've logged with it on many times and still cant find the problem. Thinking leak somewhere but i dont hear anything or cant find any leak.

 

Mine did that. I changed the fuel filter and it cleared up a lot. I will however say I don't think the fuel filter was ever changed and by ever I mean same one that was on there when the car rolled off the factory line.

 

Good info/experiences. i've also thought it might be a vacuum leak somewhere which makes sense to me because for 53000 miles alot of my lines are corroded looking

 

it might be that...mine is at 73.5k miles.

I thought it was a leak since it started after i put the sc on and started tuning but dk. Where is the fuel filter and how do i change it? lol

 

The fuel filter is under the car in front of the gas tank. There's a how to on here about doing it https://www.cobaltss.net/forums/how-...ictures-51977/

Also this

Symptom Description Suggested Areas to Test
Test 1 - No Start, Hard Start Condition No Crank Hard Start, Long Crank, Erratic Crank Stall After Start No Start, Normal Crank No Start, MIL is off (if the VREF shorts to ground)

- Check battery, battery circuits to starter - Check for a damaged flywheel, engine compression, base timing and minimum air rate - Check for a failed fuel pump relay - Check for distributor rotor "punch-through" - Check for a faulty ignition control module (ICM) - Check for a VREF circuit shorted to ground - Check SKIM (security system) with a Scan Tool


Test 2 - Rough Idle or Stalls Condition Low or slow idle speed Fast idle speed Hunting or rolling idle speed Slow return to idle speed Stalls or almost stalls

- Check for engine vacuum leaks - Check the condition of the PCV valve and lines - Check for excessive carbon buildup - Check for a restricted exhaust (in Section 2) - Check base idle speed, check for low fuel pressure - Check the throttle linkage for sticking or binding


Test 3 - Runs Rough Condition At idle speed During acceleration At cruise speed During deceleration

- Check for engine vacuum leaks at intake manifold - Check condition of ignition secondary components - Check base timing and idle speed settings - Check for low or high fuel pressure - Check for dirty, leaking or shorted fuel injectors - Check for excessive carbon buildup on valves


Test 4 - Cuts-out, Misses Condition At idle speed During acceleration At cruise speed During deceleration

- Check for engine vacuum leaks at intake manifold - Check condition of ignition secondary components - Check that spark timing advance is available - Check for low or high fuel pressure - Check for dirty, leaking or shorted fuel injectors - Check for excessive carbon buildup on valves


Test 5 - Bucks, Jerks Condition During acceleration At cruise speed During deceleration

- Check for engine vacuum leaks at intake manifold - Check condition of ignition secondary components - Check that spark timing advance is available - Check for low or high fuel pressure - Check for dirty, leaking or shorted fuel injectors - Check operation of the TCC solenoid, brake switch