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Well, it looks like I may have really messed up. I just bought a used 2009 Cobalt LT from Herts Rent2Buy, 34500 miles. I got three things fixed before the 'bumper to bumper' warranty expired at 36,000 but now at 36,400 miles the car has begun to miss very badly. At idle it will sometimes miss so strongly that it feels like it will die, but it doesn't. And it seems that the car doesn't have nearly as much power and pep as it should have.

I took it to the Chevy dealer here and they said that the 'powertrain' warranty didn't really cover everything in the powertrain, that "a lot of sensors and other things aren't covered.' I'm very skeptical of taking a car to the dealer for repairs, they tend to just start replacing things till the problem goes away - and if the parts aren't covered, I could be in for some expensive repairs. I checked with Herts (the car has a 2000 mile warranty from them) but they say that theirs is a 'limited' warranty as well.

I have a very good mechanic here, and am considering just taking it to him to see if he can figure out what could be wrong. But before I do that, I'm wondering, is 36,000 miles too soon for plug wires to need replacing? How about fuel filter? The problem started as a little hesitation and loss of power and has turned into a bad miss. I know it could be thousands of other problems, but those are the easiest I can think of. BTW, the computer isn't reading any problems - Anyone got any ideas of what I could check myself?
 

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The ignition is coil over so there aren't any plug wires....check the plugs and the harnesses going to the coils. If your balt is CA emissions it won't have a replaceable fuel filter but if it isn't than it wouldn't hurt replacing it. I'd also remove and clean the throttle body (4 bolts and a harness) with CRC TB cleaner.

If the miss is bad enough for you to feel it should be throwing a random p0300 code. Are you sure it's a miss? The idle does get crappy on these cars with the a/c running and/or with a high current draw.
 

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No codes

Yeah, I thought I'd be getting a cylinder misfire code also, but nothing - the car's from Georgia, so I don't think it has CA emission stuff - My son's Honda CRX acted this way, but he was getting a misfire indication on the computer and it turned out to be plugs that weren't fully seated (!)

I've tried to watch it when it misses, and the RPM drops by about 500 for a 1/2 sec or so - it seems to me that if it were electrical, I'd see a code, right? Maybe bad gas?
 

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This might not help, but I know when I put my K&N drop in filter, some of the ridges got pushed in on the air intake tube running into the throtle body. I thought something was wrong with the spark plugs. I just went and pushed the dented parts out and it ran fine.
Hope this helps
 

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Well, I can certainly check that - to be honest, I haven't even opened the hood since I bought the car several weeks ago - I just went outside to take a look and it's the strangest underhood arrangement I've ever seen - I suppose all that plastic comes off fairly easily and it'll look like an engine then! :)

This might not help, but I know when I put my K&N drop in filter, some of the ridges got pushed in on the air intake tube running into the throtle body. I thought something was wrong with the spark plugs. I just went and pushed the dented parts out and it ran fine.
Hope this helps
 

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Well, I can certainly check that - to be honest, I haven't even opened the hood since I bought the car several weeks ago - I just went outside to take a look and it's the strangest underhood arrangement I've ever seen - I suppose all that plastic comes off fairly easily and it'll look like an engine then! :)
LOL!! Welcome to the world of plastic engine covers!

Try cleaning the MAF -- in the intake tube between the filter box and Throttle body. Use a cleaner for MAFs (Autozone sells, for example) and make sure it's dry before reinstalling it. Another possibility is oil collecting in the PCV hole in the intake manifold. ...a little more is involved in cleaning it though -- not sure how much you know about cars -- will have to remove intake manifold.
 

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So you checked the plugs, right?
 

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I'd say bring it in. Some cars these days still need a tune up around your mileage. I have not check this out on the Cobalt yet, as mine is new, but take it in and see if they can diagnose something. That shouldn't cost too much.
 

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think about how you treat a rental car...just saying.
...think about the way you treat a rental car...I treat them as if I own them...LoL I also think about the fact that a young Mother or a young man without much money will buy the used rental cars...why should I abuse them?

I've found that most people that abuse rental cars have a tendency to abuse their own Mother's car...and complain if a mechanic abuses their car...the "I can abuse it but you can't abuse my syndrome". What's good for one abuser out to be good for another...LoL!!!
 

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lil off topic, but int he words of jeff foxworthy " this ford festa is about to see more air than a bike at the X-games" had to ad lib a bit there.

i try to treat rentals as best I can. I agree 100% with you on that one
 

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Yeah, I wouldn't beat the shit out of a rental.
 

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...think about the way you treat a rental car...I treat them as if I own them...LoL I also think about the fact that a young Mother or a young man without much money will buy the used rental cars...why should I abuse them?

I've found that most people that abuse rental cars have a tendency to abuse their own Mother's car...and complain if a mechanic abuses their car...the "I can abuse it but you can't abuse my syndrome". What's good for one abuser out to be good for another...LoL!!!
Maybe you don't treat the rental like that, but these douchnozzles certainly beat them:


YouTube - ‪THE cobalt rental car part 2‬‎
 

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yea, I can't see it on here, but that has bad news written all over it

---------- Post added 08-10-2010 at 12:29 AM ---------- Previous post was 08-09-2010 at 11:23 PM ----------

that right there really just..I can't find anything derogatory to explain my extreme disgust for what they did...but if I was to see that crap going on, i would have went midevil on them.

wow i do have some self restraint on the interwebs
 

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Discussion Starter #16 (Edited)
OK, I'm sorry that I didn't follow-up on this, but I forgot the name of the website! :) Anyway, the dealer kept the car for a week, never could find anything wrong - and the car wouldn't miss when it was there (although it was missing like crazy the week before, and the dealer saw it on his computer). Actually, the dealer was very helpful, didn't charge me anything for all the checking, even though the car had gone out of warranty. I finally picked it up, and all was fine... for about three weeks. Then I took off the engine plastic so I could check to see if the air filter was needing replacement, and it started missing again. But this time, a MAF error was showing up. So I replaced the MAF sensor, and again the missing stopped. For about a week, until I had the oil changed. Then it started missing again, giving the same MAF error. I finally figured out that the problem must be in the plug to the MAF sensor (a $90 part!!!) and after replacing it, I got no errors and the car is running perfectly. However, after removing the old plug, I saw that one of the wires was broken, and I suppose that every time I would remove the plastic cowling I'd disturb the wires, causing a miss. Glad to get everything working again, but I sure wish I'd seen the broken wire in the first place - might have saved $160 for the MAF sensor and plug!
 

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Glad to hear you got it licked. $160 is bad, but it could have been a lot more money if you had not figured it out.
 

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OK, I'm sorry that I didn't follow-up on this, but I forgot the name of the website! :) Anyway, the dealer kept the car for a week, never could find anything wrong - and the car wouldn't miss when it was there (although it was missing like crazy the week before, and the dealer saw it on his computer). Actually, the dealer was very helpful, didn't charge me anything for all the checking, even though the car had gone out of warranty. I finally picked it up, and all was fine... for about three weeks. Then I took off the engine plastic so I could check to see if the air filter was needing replacement, and it started missing again. But this time, a MAF error was showing up. So I replaced the MAF sensor, and again the missing stopped. For about a week, until I had the oil changed. Then it started missing again, giving the same MAF error. I finally figured out that the problem must be in the plug to the MAF sensor (a $90 part!!!) and after replacing it, I got no errors and the car is running perfectly. However, after removing the old plug, I saw that one of the wires was broken, and I suppose that every time I would remove the plastic cowling I'd disturb the wires, causing a miss. Glad to get everything working again, but I sure wish I'd seen the broken wire in the first place - might have saved $160 for the MAF sensor and plug!
Yeah... electrical wiring can be a ***** when it has a break. Kinda like headphones.. You move the wire and the channels keep cutting in and out.
 

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if it happens again try using some seafoam... i had a similar problem a few weeks ago. checked all plugs and wires ant maf and tb... put some seafoam in the tank. some in the oil about 150 mi before i changed it and put some in the vacuum line. totally cleaned out my engine. runs better now to. dont be alarmed by the large amount of black smoke coming from the tailpipe. i will try to do a write up if there isnt already one.
 
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