Idle problems.

[Vitamin CC]

Alright, so I have a 2000 alero 2dr. Its got the 3.4 V6 and its automatic. I don't know a heck of alot about this power plant, this is the first car iv ever owned and iv only had it for 2-3 months.
Anyways, my problem seems fairly simple but im not sure what i should check. The car starts fine and runs very smooth. But, once the engine warms up, it hunts when it is idling. (the engine RPM drops and then picks back up)
This only happins when it is warm and idling, not wile your driving.
I was thinking it could be a sensor...but im not sure what sencer to check, were that would be and how to check it.
Any ideas would be much apreasheated.

[Nate's Alero]

IAC sensor, TPS sensor, MAP sensor....etc...o2 sensors

vacuum leak?

fouled plugs?

[Vitamin CC]

I put new plugs and wires in a few days after I bought it. How would I go about testing for a vacuum leak ? Not to be a pain in the ass but im a bit of a rookie so to say.

[CactusWill]

Check engine light on?

[Gr1m]

i would check MAF sensor or IAT sensor but sounds most likely its your MAF sensor or a vacuum leak

[Redog]

^^ Yeah I vote for a vacuum leak

Check the elbow on the front driver's side of the manifold right next to the throttle body. That elbow rots away very easy and GM doesn't carry it.

$2.00 for a vacuum tee and some hose and it's fixed ;)

[Vitamin CC]

alright, I finally got a day off work tomorrow, so hopfuly after school I can take a look at it. If its a vacuum leak and it is from a rotting elbow like you are subjesting, im just trying to picture this in my mind. standing infront of the car with the hood open, on the far drivers side, there is the air box, rubber/plastic hose goes over to into the intake, the aluminium thing with all the lumps on it directing air into the cylinders. But just before that there are wires and crap all pluged into the rubber line from the air box. Thats were your telling me to look for this rotted piece ? And if there is no rotting elbow would my next best bet be the MAF ? (Mass Air Flow if im correct) is there any way to check that as well ?
And thank you all for helping me through this, I wasnt really sure were to start. Hopfuly I can get this figured out soon though.

[jayson_waltz]

sounds exactely like a vaccuum leak. the thing you said with all the wires plugged in is your throttle body, yes thats where a vaccuum line hooks to with a 90 degree angle coupler.

[Vitamin CC]

alright I took a look at the throttle body today and i didnt see anything that looked rotten. and if it was something that was rotten wouldnt it affect the idle all the time, not just once it warms up ? could this mean its pointing to a sencer ? doesnt this engine have a defalt mode that bypasses the sencers untill it warms up ? oh ya, to the fellow that asked before the check engine light is not on. hopfuly some of this makes sence....lol

[Qcksilver]

I also am having an idle problem that i'm hoping you all can help me figure out. At idle my alero seems to be fighting to find a good idle speed and even shakes the car back and forth. almost like it's lunging forward then resting back. does this make sense to anyone? by the way I have a 2.4 L 4cyl. and it's a 2000 alero if it makes a difference.

my check engine light is on. the hose that goes to the intake air temperature sensor did have a hole in it so i've since put the original intake systme back together. still same problem.
then i replaced all 4 spark plugs. all 4 old plugs had white tips on the gapped end. (not sure if this means anything) new plugs did nothing, same problem.
then i replaced the fuel filter, still i have the same problem.

all these things i really needed to do anyway cuz it was time but none of them fixed my problem. a buddy of mine let me borrow his OBD II scanner thing and it came up with this code P0171. can anyone decifer this for me?? any help would be great. thanks guys & gals.

great...now my signature doesn't work either. awesome. this just isn't my month. lol

[Steven01]

[QUOTE=Qcksilver;405967]I also am having an idle problem that i'm hoping you all can help me figure out. At idle my alero seems to be fighting to find a good idle speed and even shakes the car back and forth. almost like it's lunging forward then resting back. does this make sense to anyone? by the way I have a 2.4 L 4cyl. and it's a 2000 alero if it makes a difference.

I sorta have the same problem. But no engine light no lights at all. I have sea fomed ive changed plugs have not touched sensors yet..

I don't know, but some one did tell me that it is just my car trying to find it idle. But doesnt make sence to me why it would be fine when cold and once temp is Nice and WARM it almost doese it at every stop..;)

[Qcksilver]

Steven01--I'll believe that it's the car trying to find the idle but the question is why is it happening? i've had my alero since 2000. bought it brand new and this is the first time it's done this to me.

one more thing i've noticed with mine that i forgot to add yesterday. my Trac Off light that's under the Check Engine light has been coming on also. and sometimes it doesn't want to go out even though i've pushed the button next to the shifter. from time to time it goes out on it's own. not sure if it has anything to do with my problem but the two lights seem to have come on around the same time.

anyone out there have any ideas?? anything at all??

[dtldiaspora]

if your check engine light is on, get someone to scan the codes for you might help you find out what your problem is.

Autozone, a friend anyone you know who has a scanner that will get the codes

[Qcksilver]

if your check engine light is on, get someone to scan the codes for you might help you find out what your problem is.

Autozone, a friend anyone you know who has a scanner that will get the codes

a buddy of mine let me borrow his OBD II scanner thing and it came up with this code P0171. can anyone decifer this for me?? I read about the code, it means the car is running to lean. but what does that mean? what do i need to change? any help would be great.

[[ion] C2]

one more thing i've noticed with mine that i forgot to add yesterday. my Trac Off light that's under the Check Engine light has been coming on also. and sometimes it doesn't want to go out even though i've pushed the button next to the shifter. from time to time it goes out on it's own. not sure if it has anything to do with my problem but the two lights seem to have come on around the same time.
The same thing used to happen to me... with the same P0171 code... it occurred immediately after I installed my narrowband air/fuel ratio gauge and tapped into the O2 sensor's wires. Ever since I disconnected that gauge, it's never happened.

Sounds to me like a vacuum leak; you're getting unmetered air in somewhere.

[Qcksilver]

where do you think it might be? is there a common place where these type of vacuum leaks happen more often than not? any ideas or help would be great.

i read on another web site that it could be clogged injectors or even a bad fuel pump. does that make sense to anyone? is there an easy way to find out what it is, cheap? i mean without sending it to the shop.

[Gr1m]

clogged injectors and new fuel pump is expensive, and it sounds like a vacuum leak anyway. i would take a look at areas near your TB and see if any gaskets are cracked or anything looks out of place

[Qcksilver]

Just to be sure, TB means throttle body, right?? or are u talking about something else.

by the way, i don't know if it makes a difference but my 2000 alero has 38,000 miles on it.

[Vinalero]

Just to be sure, TB means throttle body, right?? or are u talking about something else.

by the way, i don't know if it makes a difference but my 2000 alero has 38,000 miles on it.

Holy moly thats some low mileage!

[Qcksilver]

Yeah, it is very low miles. I don't drive it very often. i fly for a living so my alero basically just takes me fromt the house to work and back. mostly it just sits in the parking lot at work waiting for me to return from a flight. which lasts around 5 days to about 2 weeks. when i'm home we always drive my wifes car so the alero just sits in the garage, waiting patiently.

anyway can anyone answer my question? TB means throttle body, right? or is it something else.

[Vinalero]

Yeah, it is very low miles. I don't drive it very often. i fly for a living so my alero basically just takes me fromt the house to work and back. mostly it just sits in the parking lot at work waiting for me to return from a flight. which lasts around 5 days to about 2 weeks. when i'm home we always drive my wifes car so the alero just sits in the garage, waiting patiently.

anyway can anyone answer my question? TB means throttle body, right? or is it something else.

Yes, TB means Throttle body.

[Qcksilver]

Thanks Vinalero, I'll check out the TB area and see what I see.

[[ion] C2]

spray carburetor cleaner all over the place at idle when the engine is running while somewhat cold, if you hear a loud hiss and the liquid disappears quickly, you found a leak. carb cleaner should also cause the idle to jump up.

concentrate on all the vacuum hoses you can see, and where the intake manifold meets the head

[Qcksilver]

i haven't checked for the leaks yet cuz of a flight i needed to go on for work but when i left the other morning i noticed something on the driveway when i left home. it may have been there a few days but i just never noticed it.

a black spot that clearly came spraying from my exhaust pipe was marking the driveway. not sure what it means, if anything, but i know it's not normal.

does this mean anything to the car guys or gals out there? does this jive with my idle problem i've been talking about or is this something completely different? please help.

[Steven01]

i would'nt think that the black spot on drive way would have to do with your idle. Hmm but black spot? lots of carbon build up in the system mabby.


And I cant find antyhing rong with mine..... Ive checked when its cold and hot. its been -10 here for few days i belive thats cold enough ;p And all my lines are good no leaks. So if anyone could help me on my same probem that would be nice.. (no check engine light).