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Sedans Chevrolet Cobalt Chevrolet Cobalt
2164 messages, Last post on Nov 05, 2009 at 5:08 PM
You are in the Chevrolet Cobalt Forum. Your Hosts are pat & karens
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Replying to: imidazol97 (Dec 01, 2008 6:50 am) I had a alignment from the dealer and tires balanced, didnt seem to help much. I was told that the tire treads get caught in the grooves in the freeway, more with some tires than most, but who knows if they were just storying me. |
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My '09 Cobalt has no problems with NorCal rain grooves, my '09 Focus does. Go figure. The last 10 or so cars I've had with stock or aftermarket tires have had no rain groove problems. If it bothers you a lot, try switching to a tire with a much different tread design. Falken ZE512's, Kumho KH16's, Bridgestone 960's (mine were the last gen 950's) are all tires I've had good experience with. As for your ride being harsh, go test drive a new Cobalt and see if it is better or the same. Ride is very subjective, and also depends on the roads. The Cobalt has a nice ride imho and by most 3rd party accounts (including the recent test on this Edmunds site). While there could be a shot shock or strut on your car, it's unlikely these days. Bounce each corner (get out of the car and shove each corner of the car up and down) and see if you notice anything out of balance between corners. If you need to replace a strut or shock, a replacement Chevy part shouldn't cost that much. Generally I Google to find an online dealer that discounts parts and use my VIN (i.d. from my car) to order from them then have it installed at the lowest cost shop in my area. Tire Rack has a good list of recommended installers for shocks and tires. 35 psi is what I run all my cars at. It used to seem high, I got used to it, it's better handling, better tire wear, better mileage, and more margin for error if you lose some air. But get a good tire pressure gauge, go to a Napa parts store and get their "pencil" style gauge which is cheap and accurate. Don't fall for the "digital readout" gimmicks. CR gave the Napa gauge good marks for accuracy and repeatability. |
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I see no reason NOT to run the recommended tire pressure, especially with the original equipment tires. Overinflation will make the car ride rough, not handle as well, and will cause the tires to wear out in the middle. Underinflation will accelerate the wear on the inner and outer edges of the tires. I go with the recommended 30 psi, and I am happy with the ride and handling. Time will tell as far as how evenly the tires will wear. Tom |
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Replying to: steve333 (Nov 30, 2008 10:00 pm) For years I've always ran a bit higher pressure on my front tires, if front wheel drive. Have seen a more even wear pattern on several vehicles. |
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I don't know why GM makes this information so hard to find, but here is a fact sheet from the GM public relations department on some of the technology incorporated into the 2.2L engine that powers our Cobalts. It's fun to learn that, yes, GM DOES have a great engineering side to its operations, and isn't all about cutting costs: http://media.gm.com/us/powertrain/en/product_services/2009/Stories/Ecotec/09_LAP- _n.doc alternately, go to media.gm.com and search for 2009 Ecotec 2.2L Just cut and paste this string and drop it in their search box, and after the initial search comes back, check the "Powertrains" subheading in the left column to narrow the search. Also be sure to check the "search for all words" button under the search box, and after you follow those two steps, item 5 should be the link to the article. Like I said, GM's public relations department doesn't make a gearhead's life any easier, but the article is worth reading. Here are some interesting exercerpts: "The [2009] Ecotec 2.2L starts with a refined engine block, introduced for 2006 with the Ecotec 2.4L I-4 VVT (RPO LE5). The Gen II block was developed with data acquired in racing programs and the latest math-based tools. Both the bore walls and bulkheads, or the structural elements that support the crank bearings, have been strengthened, with only a minimal weight increase (approximately 2.5 pounds). The coolant jackets have been expanded, allowing more precise bore roundness and improving the block’s ability to dissipate heat. Coolant capacity increases approximately .5 liter." "The [2009] Ecotec 2.2L VVT I-4 also benefits from cylinder head refinements introduced on the 2.4L VVT. The exhaust ports have been enlarged slightly to expel exhaust gas more efficiently." The 2009 Ecotec 2.2 used in the Cobalt apparently also has improved materials for the valve seats and certain other engine parts to allow it to use E85 fuels in certain applications. Although only the HHR version is certified for E85 use, APPARENTLY all 2.2s have the durability upgrades, but only the HHR version has the revised fuel injectors that allow higher volumes of fuel delivery which is required with the lower-energy E85 fuel (so don't go trying to run E85 in your Cobalt! - it's apparently very corrosive stuff). The ECM in the HHR reprograms the engine "on the fly" based on feedback from the O2 sensors and other engine sensors to adapt to ANY mix of E85 - which is great since the first and last tanks of E85 are going to have a different percentage of alcohol until the gasoline is all flushed out when you start using E85 and until the E85 is all flushed out when you switch back to gas. (It's not clear that non-Flex Fuel vehicles, like our 2009 Cobalts, also have the same software programming, but given that other portions of the article stress GM's desire to have uniform manufacturing as much as possible across the 2.2 line, and given the fact that many states mandate E10 - 10% ethanol - for ALL vehicles, very likely the Ecotec does have this "fine tuning on the fly" ability - GM brags about the much higher engine sample rate used in ALL the 2.2 versions, for example.) The VVT or variable valve timing system used in the Ecotec isn't a primitive system - it arrives to the Cobalt with completely variable valve timing on BOTH intake and exhaust valves, and the variability is NOT just linked to RPM - it's also linked to driving loads, and throttle usage. I think this is what Toyota offers on its VVTi or "variable valve timing with intelligence" system. So if you get on the gas pedal while at low rpm, the engine reprograms the camshaft timing from optimal fuel economy mode to optimal performance mode RIGHT AWAY not 2,000 rpm later. Of somewhat more technical interest (to the gearhead, of course) is that fact that GM seems to operate the 2.2 in mild "Atkinson" cycle mode (if I got that right): "The cam phaser is timed to hold the intake valve open a short time longer than a normal engine, allowing a reverse flow into the intake manifold. This reduces the effective compression ratio, allowing the expansion ratio to increase while retaining normal combustion pressures. [That's the "Atkinson" effect vs. the traditional "Otto" 4 stroke cycle.] Efficiency is gained because the high expansion ratio delivers a longer power stroke and reduces the heat wasted in the exhaust. This increase in efficiency comes at the expense of some power from the lower effective compression ratio, but that can be compensated for by the overall higher mechanical compression ratio. [As we know, the Ecotec 2.2 has 155 hp and 150 lb-ft of torque this year, up considerably from last year, so apparently the performance has only improved, not been hurt.]" If you download the h.p./torque chart for the 2.2 (a different document from the link above), you'll see that at higher rpm the torque doesn't fall off, it stays strong and h.p. keeps increasing. The Cobalt cries out for a 5 speed! (And the "old," "non-fuel economy maximizng" ECM software on the automatics - the newly programmed automatics don't like to downshift as easily as before.) |
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I already posted this in another forum and reposting is probably poor form but oh well i really need an answer to this question. all the websites and forums say the 2009 cobalts are bluetooth capable but mine refuses to let me hook it up. the gm website says to push the call button and say 'blue tooth' but that isnt working. any ideas?
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Replying to: iluvnanny (Jan 07, 2009 5:45 pm)
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Replying to: dispencer2 (Jan 08, 2009 5:01 pm) Again, as stated above, if you did not purchase the option for Bluetooth then it is not set up for that. |
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yeah okay im a moron. i did not get the bluetooth package. thanks tho for the help.
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Replying to: iluvnanny (Jan 09, 2009 9:48 pm) |
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