Ride not smooth at speeds of 75 mph and above in 2007 Toyota Corolla. Why?

(2012-02-05 15:20:08)

1. math Says: I just started to notice that the ride does not seem smooth at speeds of 75 mph or above. It seems the engine whines, coughs and that the car rattles. This coughing type of thing is cleared when pressing the gas pedal harder. But few minutes again this same cough seems to appear. I get scared as if engine is going to fail or stall but it doesn't. The car has 58,000 miles on it. The car seems to bounce little bit at too. I don't recall this happening before. I cannot figure out why. Everything looks good from the exterior and everything under the hood looks good too. The tires are not that old as they have only 14,000 miles on it and they look as if installed yesterday. Tire pressure is good too. From naked eye everything looks good. But ride is shaky, bouncy, whiny and car seems to cough at 75 mph or above and it also feels as if engine is going to stall (but it never does). This is interstate driving. I heard that interstate highway driving is best for car and is easiest on car. I get oil changed regularly. Alignment done recently too. And all service done at dealer

2. Ramon C Says: Well, you heard totally wrong information about Intestate miles on cars, and besides, this car is telling it is sick. Look, cars must fight wind resistance. This is called drag. From 50mph to 70 mph this resistance increases 100%. Add 5 more miles and since wind drag increases to the square of the speed plus wind factor, this rather poorly maintained Corolla is pushing just about the limits of the engine and transmission. Sure people drive even faster. But you are correct to be concerned and you need the services of a mechanic. I mean, is that logical or not? Take it to a repair station before you damage the motor and it costs even more to repair. By the way, driving that fast is not only illegal but it is very wasteful. You use more gasoline. The tires wear out faster. The engine struggles and the drive train is stressed. Already the motor is telling you it has been abused. Slow down before you get killed or severely injured. 825 people each day get severely injured in car crashes in the USA all in the name of speed. Are you willing to risk your health or you life for saving a few minutes? Plus you fuel bill must be huge! Slow down and have this car repaired by a professional

3. math Says: also 16 states in US have speed limit of 75 or higher. Read wikipedia to get some brain cells

4. ruth Says: I would pop it
In to a local garage could be u hit the curb and knocked out the tracking in which case very soon the
Tyes will wear out but doesn't explain the caugh could be fuel injectors

5. Mark F Says: Because you are exceeding the speed limit.

6. g-man Says: I'd check two things because I don't think the two symptoms are related. The shaky ride could easily be a tire out of balance, an alignment doesn't address the balancing and if you've thrown a wheel weight on one of the tires it could account for the resulting shakiness.

The other issue could easily be something as simple as a dirty fuel filter, dirty throttle body, a bad coil or coil pack or a bad sensor. Take it to an auto parts store and have the codes read, that could point you in the right direction as far as the engine issues.

Neither of the issues might show up at lower speeds because the out of balance condition always becomes more pronounced at higher speeds and the engine issue when more fuel is called for at higher speeds.