rough idle dying under 1k rpms

notomorrow · 01-07-2011, 05:58 PM

2000 alero, 2.4l auto, has a really really rough idle, was led to believe it had something to do with ignition, ive replaced a cracked coil pack housing, spark plugs, boots, had the icm tested and it was bad, replaced with one that tested good, still rough idling, im about to switch out the coil packs with another pair and see but i doubt it will work... only other option i can think of now is the IAT...but im unsure how to test this, and i cant afford to just throw parts at the car anymore... please help, i love this car and i dont want to get rid of it, but ive been frustrated for a year and a few months now...

Lucalare · 01-07-2011, 06:16 PM

sounds like a vacuum leak, especially if it goes away in upper RPMs

notomorrow · 01-07-2011, 06:24 PM

if im not mistaken i have checked for that, and replaced a few cracked hoses... cant seem to find any other leaks, but i will double check once i get this other cover back on

robalero · 01-07-2011, 08:51 PM

try taking your boots off and stretching the springs if you hadn't done this yet

notomorrow · 01-07-2011, 09:12 PM

hmm...not sure i know exactly what you mean rob, please elaborate if you can, also replaced IAT sensor today.. didnt help at all, picked up some brake cleaner to check again for vac leaks, didnt see any when i sprayed up at the shop, will check again in the morning, somebody i talked to suggested it was the IAC or something, at this rate im so overwhelmed but im going to keep at it, please keep helping guys i really appreciate it

*EDIT* I just Re-Read your post rob, that was something i hadnt even thought about, in fact i didnt think those springs came out but now that i know this, i will definitely try that in the morning also and let you know, as for now the problem is still there...

robalero · 01-07-2011, 09:30 PM

let us know

widbyj · 01-07-2011, 10:06 PM

Is the Check Engine light on? Have you had the codes read?

It sounds like coilpacks are the only ignition part that hasn't been replaced yet, if you have a set available it won't hurt to try them.

Does sound more like an air issue though. Vacuum leak would be the first to check but it could be an EGR issue, time to clean and replace. See the last 3 posts in this thread - http://www.aleromod.com/forums/showt...hlight=EGR+2.4

notomorrow · 01-08-2011, 07:25 PM

No CEL or SES lights, no codes, last code i had when this all started was a p0420 or somethin random multiple misfire...but since i had them cleared it hasnt thrown a code since. As far as the coilpacks, i recieved an extra in the idi cover i picked up that supposedly came from a car that was running good, swapped covers.... no change...checked for vacuum leaks in a few areas with brake cleaner.. but didnt see or hear anything out of the ordinary :*(

notomorrow · 01-10-2011, 03:42 PM

ok, stretched the boots, correctly gapped the plugs, icm is good, coils seem to be good, coil housing is fine, replaced IAT sensor, checked again for vacuum leaks none found...checked out some of the sensors, TPS, IAC, no EGR on this car, they all looked to be fine. so far ive made a tiny bit of progress, it now only idles rough when the car is almost fully warmed up, still clueless as to what the problem is...

widbyj · 01-10-2011, 06:36 PM

At this point I suspect leakage is still the issue. I'd get the compression tested, preferably when cold and then again as soon as possible after it gets warm and causes trouble. Most likely something is opening up when warm and allowing leakage...

notomorrow · 01-10-2011, 06:42 PM

ok that being the case i either need to figure out how to compression test it myself, or find somebody around here who does it for free/cheap, most parts shops and mechanics around here have been of no help, they all look and tell me, "i have no idea whats wrong with it, have you taken it to a mechanic" last mechanic i took it too said something about it "MIGHT" be jumped timing, and would start at around $600 to start diagnosing and fixing, that was a GM dealership that quoted me that about 6 months ago...

clutch1 · 01-10-2011, 07:13 PM

How are you vacuum leak testing it?? If you're not doing it with smoke you might as well not even be doing it. Sounds like a vac leak, like they said.

cherrington17 · 01-10-2011, 07:27 PM

fuel pump getting weak?

notomorrow · 01-10-2011, 09:48 PM

in reply to clutch1: been spraying brake parts cleaner around like a few of you on here, and the guy up at oreillys has told me, was getting unsure of how the heck i can listen for a weird idle while spraying if it doesnt have a normal idle to begin with haha, as for smoking it, ive seen that mentioned a few times, but unsure as how to do it will look into it i guess...And Cherri, i will be looking into that.

notomorrow · 01-25-2011, 06:23 PM

All the fuel injectors sound like theyre working(screwdriver test) i still need to test fuel pump, IAC, looking into how to test those, still looking for vacuum leaks almost every other day.. no luck...
got around to pulling the 02 sensors yesterday...remembered a code i had awhile back, cant remember exactly which code but a bank/sensor code for the O2, anyways..pulled both.. upstream is warped and charred black, downstream is pretty blackened with what looks like some white scorching, will take pics when i get back, gonna replace the front one since thats about all i can afford to do for now lol, figure theres no harm in throwing parts at my car as long as the parts are actually needed right lol..

[ion] C2 · 01-25-2011, 06:26 PM

It's a damn vacuum leak quit going insane searching for other causes. The O2 sensor may have an impact to your problems, to see if it fixes anyrhing, unplugging it electrically will rule it out.

Find it, fix it.

BlueLego · 01-25-2011, 08:46 PM

i had a rough idling problem but that was a motor mount issue just causing alot of vibration

clutch1 · 01-25-2011, 10:47 PM

Smoking is simple. Take the intake tubing off and cap off the throttle body. Unplug the booster hose and put the smoke machine nozzle into then. Then turn on the smoke machine and pump smoke in.

Find a decent independant shop and I bet he'd do it for 10 or 20 bucks quick and then you'll know for sure.

Spraying carb cleaner around all the questionable areas is just a PITA and hard to hear the idle changes.

notomorrow · 01-31-2011, 07:39 PM

clutch, shops around here, want 89.99 just to smoke it, they want the same amount to pull my code history...anyways, replaced upstream 02, it was pretty toasted.. no change still the same problems....i sprayed the other nite for vacuum leaks, and had a bit of a change when spraying around near the firewall, but havent tracked it down yet not sure if i was imagining it or what, but when it gets warmer i will look...unless you guys know a do it yourself almost free way to smoke it, then im at a loss because i cant afford 90$ for a TEST....

notomorrow · 02-04-2011, 11:02 AM

BUMP... waiting on tax return then im probably going to just go rent a fog machine from a party shop i did some googling and it looks like they are relatively safe to use for smoking the engine and a heck of a lot cheaper...if this isnt a vacuum leak then im at a loss and probably going to sell the car...as of right now, ive put more money into the car in just the last 4 months than its actually worth...