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Problem with engine hesitation, might be simple.

pa356228pa356228 Posts: 34
edited June 1 in Chevrolet
I have a 2006 Chevy Cobalt LS (4 door-sedan) with 52,800 miles. Sometimes when I slow down and stop at a street light (not a speeder and don't stop fast), it seems like my car wants to stall. When I get moving again it's fine, it could be a simple thing to fix but any suggestions?

I change the oil, oil filter, air filter, carbon air filter every 3,000-3,500 miles but, still seems like something else is clogg. None of the sensors comes on. Don't want to take my car to a chevy dealer to get service if I don't have to. Trying to save money. Anything is helpful.


  • laserbluelaserblue Posts: 313
    When was the last time you got a good tune-up done on your Cobalt?
    Clean the injectors, change the spark plugs (even if G.M. says only at 100,000 miles), check or change the wires (might be damage)?
    It's nice to change all the filters but there's a little more to it.
  • pa356228pa356228 Posts: 34
    Ever since I brought my car (March 2006) I never had a complete tune up on it, besides the basics. Change the spark plugs about 3 weeks ago, at first, it didn't want to start. After a few tries, my car finally did start. The wires are in good condition, also the hoses, clamps, gas cap, and couple of bolts needed tighten. Never clean the injectors, though. Or the fuilds.

    Going on a vacation on April 29, 2009 to Pennsylvania, It's going to take 8 hours of driving or 450 miles. Do you think it is the injectors that could be causing it? How can I clean them?
  • laserbluelaserblue Posts: 313
    Pep Boy or Auto Zone must sell what you need for that. I've seen people do it by themselves. You plug this injector cleaner (it looks like its a bottle) somewhere on the engine and start the car and it seems to do the job by itself as the engine runs. I usually go to the dealer but you seem to like to do your own work on your car.
  • pa356228pa356228 Posts: 34
    Did try the injector cleaner, it seems like it's working. I'll give it 2 days to see results. The engine runs alot quiet now. Hopefully it works, thanks. By the way, sometimes the "check gas cap" sensor comes on once in awhile. Do you think the hesitation has anything to do with that also?
  • laserbluelaserblue Posts: 313
    It's possible and probably it is.
    With today's electronics and computerized gadgets in cars anything is possible.
    I had a car once and at every fill-up I had to turn the gas cap at least 3 full turns (clicking sound) if not my "check engine" light came on.
    The first time that this happened to me it cost me 10$ at the dealer to know this and to reset the system. The mechanic said I could do it by myself by turning my key to acc. 40 times "non stop".
    Go figure!
  • pa356228pa356228 Posts: 34
    Now I'm thinking of it, can't be the gas cap because did brought a new gas cap about 3 months ago locking method with key lock. On cap, it says 3 full clicks to lock. (probably with the same one you have also) About a month ago, when left the driveway, the gas cap sensor came on. But, the hesitation started in june 2008, the car dealer service department couldn't fine anything wrong. Yet It still pass inspections and pre-trip inspections from this day. (I drive 18wheelers)

    Anyways, the injection cleaner (so far) is working. At street lights fully stopped, the engine runs alot quiet than what it was running before couple of days ago. Not sure if it did the trick or not, but it's helping. I'm going on a vacation on wednesday leaving VB,VA to Pittsburgh, PA (450 miles/8 hrs) it will be a long trip. Of course, driving, rather drive anyways. Getting an oil change before going up and hopefully it does fix the hesitation this time, could use your advice more. Can you think of anything else that could be causing it?
  • poncho167poncho167 Posts: 1,178
    Be sure to use could quality gas instead of the cheap stuff.
  • horsey55horsey55 Posts: 15
    Good point, I run Shell V-Power 93 or Kwik Trip 91 for you Midwesterners with no ethanol and I will consistently get about 2 MPG better than ethanol lased regular.
    I am currently running 150 miles a day. Doing my motor good. :)
  • pa356228pa356228 Posts: 34
    Just got back from vacation 2 days from Pittsburgh, PA, the engine hesitation have gone away, but now something else occured when I came back. I think something is wrong with the transmission. Anyways, no matter what speed I go, when I need to slow down to make a stop, of course the rpms will go down. But around 10-5mph
    the rpms goes up another 100 and then goes down to normal. Then the light bulbs dimmers for a few seconds. There is no leaks, and in the vehicle menual, it says to change transmission fluid and filter every 50,000 miles. My car now has 54,944, probably it is time.

    Before I do get it change, any ideas on what else could be causing it for I can find alternatives without having to spend alot of money. Any feedbacks is helpful? sorry about asking to much questions?
  • pa356228pa356228 Posts: 34
    Thanks for all your help, and sure enough more problems will occur soon or later. However, I do have just one question? Could be a dumb question, but need to know. Actually two questions, 1. How can I check the transmission fluid? ever since I bought my car, could never find the dipstick for transmission fluid. and 2. Does cobalts have a fuel filter? if so, can you please tell me where it is located for I can change it.

    Any feedbacks are helpful, and once again thank you for your help.
  • cobalt943cobalt943 Posts: 5
    1. Transmission doesn't have a dipstick. There is a plug on top of the transmission. You would be better off letting a dealership check it.

    2. The fuel filter is under the car between the fuel tank and back seat. If you look under the car between the two rear wheels, there is a metal beam connecting the rear suspension. The fuel filter is above the beam.
  • pa356228pa356228 Posts: 34
    When I were finish washing my car on Monday, and were using a towel to dry off my car, I've notice the driver's side headlight had mositure inside the len cover. Never had that problem when washing any of my vehicles before. Anyways, I checked for cracks on the len, gaps around the len and couldn't find anything that could cause it.

    The headlight and turn signal bulb still works fine. Should I be concern about it? What do you think? Just for the record, my car were sitting for about an hour or two after I drove it to somewhere, and it was 75 degrees outside that day. Also, the passenger side don't have that problem, yet. Any advice?
  • pa356228pa356228 Posts: 34
    I did found the solution about the moist in the headlight lamp. Which still occurs now and then but, there is a another minor problem which could lead to major. Here it goes, everytime when I need the defoggers while driving, my car starts hesitating when slowing down at a traffic light on red.

    Well, in other words, when slowing down to 5 mph my rpms starts frustrating between 700 up to 1300 rpms at 3 mph. When my defoggers (defrosters) are on but, when I turn off the defoggers (defrosters) it returns to normal readings. I know it probably doesn't make any sense to you either but, any advices will be hopeful.

    Next 2-3 weeks I will buy a book for repairs, do you think Advance Auto Parts or Auto Zone will have one?
  • tcaloftcalof Posts: 29
    I assume by defoggers you mean your defroster mode of the HVAC controls. When you select the "DEfrost" setting, your AC compressor automatically kicks in. When that happens, the PCM tells the engine to increase the idle speed because of the increased load of the compressor. Your engine cannot hold that new idle speed and the speed starts fluctuating. The problem could be: rapid cycling of the AC compressor caused by insufficient R134a charge or a dirty throttle body causing the bypass air around the throttle plate to give an erroneous reading to the PCM. Start by looking at the throttle plate and throttle body and clean if necessary. Does your AC work OK? If not, look at getting the system diagnosed and recharged.
  • pa356228pa356228 Posts: 34
    I had the AC fixed 2 years ago or alittle lesser. I only used the AC twice this year and the first time this year, my car ran normal with it on without the fluctuating. Actually, the first time was when I where driving on the interstate but, for the second time I used the AC, that's when the fluctuating started. (About 4 months ago.)

    Do you think I should buy a new PCM? About the throttle plate and body, I know this is a stupid question to ask but, Can you tell me where the throttle plate and throttle body is located? Wished I were a mechanic. However, I do fix some minor repairs. Definitely, next paycheck I will buy a auto repair book.

    Also, one more thing. What's the best place to go to buy a auto repair book?
    Sorry about asking too much questions.
  • tcaloftcalof Posts: 29
    No, don't buy a new PCM. The throttle body and plate are located at the intake manifold. Follow the big black plastic tube from the air filter box to the engine. You need to remove this tube to get at the plate. Do yourself a favor and buy a Haynes manual at any auto parts store. You need to know what you're doing or you can seriously damage your engine if you drop something into the throttle body. I would suggest seeking the help of someone who does know what they're doing so you can learn by watching. Otherwise, take the car to any reliable shop. These cars and engines are everywhere and are easy to work on and diagnose.
  • pa356228pa356228 Posts: 34
    I will take my car in to the shop next Friday, also for an oil change. I was going to attempt taking off the air filter and housing to check the throttle body but, like you said "need to know what you're doing or you can seriously damage your engine if you drop something into the throttle body" I didn't want to risk it.

    Overall, everything else runs good, some minor repairs but nothing major yet. Although, my 06 Cobalt LS has about 59,801 miles. Had 105 miles since I got my car almost brand new. In Sept. 2006 I fell asleep at the wheel and done about $4,000 in damage to the front end of the car. still concerns me, what else could go wrong.

    Are you a mechanic? if so, maybe you can teach me a thing or two. Thanks again for your help and hopefully the shop can fix the problem without it being too expensive.
  • tcaloftcalof Posts: 29
    "Are you a mechanic?"

    No, just an experienced (40+ years) DIY'er. I learned on points and condenser ignitions, carburetors, and no computers. Very different today. Easier in some respects but much more difficult to diagnose when problems do arise. Unless you have a factory scan tool it's best to bite the bullet and take it to a competent mechanic. You'll pay less in the long run than just throwing replacement parts at the engine until you find the problem.
  • pa356228pa356228 Posts: 34
    Well, I took my car to the shop but, they said they couldn't find anything wrong. Nothing wrong with the senors, even the check engine light doesn't come on. Once in awhile it does when the gas cap is loose. The throttle body is clean, filters are good, guess I shouldn't worry about then. Until, it does gets alot worst. Still doesn't seem right. Any suggestions about the last recently message I've posted or Ideas? Thanks.
  • pa356228pa356228 Posts: 34
    Tomorrow morning (08/21/2009) I will bring my car in the shop for an Oil Change.
    Also, getting new filters, and was thinking of getting the O-Ring (something like that) replaced as well. Never change the O-Ring while getting an Oil Change for any of my vehicles I used to have. Anyways, Should I get the O-Ring or some kind of ring that is use for the Oil, replaced?

    I heard someone saying something about an O-Ring was bad and Oil kept on leaking, as she took her car in the shop for an Oil Change and asked about the leaking problem. The mechanic said a Ring was bad which caused the oil to leak and she suggest everyone to get the Ring replace while getting the oil change.

    Not sure what O-Ring (something use to protect leaks, besides the seal or gasket) she was talking about. Maybe, someone might know. Can someone help me understand, wished I were a mechanic, as I still haven't brought a repair book yet.

    By the way, I will be going to Tontitown, Arkansas hopefully before the weekend, so I'll keep everyone posted. Thanks...
This discussion has been closed.