gas pedal stopping problem

[hannahpenn08]

Hi so recently my 05 Chevy Malibu broke down at a stop light. A couple days earlier on my way home the warning light TC (traction control) came on and the gas pedal would not work so I pulled over, turned off the car, and turned it back on. The problem went away. A couple days later the same thing happened to me on my way to class and then when I was leaving class but this time, the car would not crank back up. I had to get a tow to a mechanic who informed me that my engine was shot so I payed to have another used engine put in. My car was returned to me Thursday afternoon and I had no problems until Friday afternoon when I was on my way home from work. I was braking to make a turn onto my road and the TC light came on along with a message of engine power reduced. I pulled over, turned it off, turned it back on, etc. Then when I was pulling into my driveway the gas pedal "turned off" again. I drove the car this morning to take the mechanic but they were closed. The car gave me no problems. I am a bit of a rough driver. I have a lead foot but I have been taking it easy since I got the car returned to me. Did I brake too fast and that's why it happened again? Can anyone tell me what the possible problem may be? Did I even need a new engine because obviously I still have the same problem but am out a lot of money? Any replies would be appreciated. P.S. I do plan to take it to the mechanic this upcoming Monday because the engine is still under warranty.

[Tech II]

Unfortunately, the horse is out of the barn......no one can tell you if the engine was bad or not......you do not replace an engine because a mechanic tells you the engine is "shot"....

Your initial problem, could have been a TAC problem......TAC means throttle actuator control......what this means is, older cars had a throttle cable directly attached between the gas pedal, and throttle plate of the engine...you step on the pedal, the cable moves, and since it is attached to the throttle plate via a linkage, the cable DIRECTLY MOVES THE THROTTLE PLATE......The more you step on the pedal, the more the cable moves, and the greater the opening of the throttle plate in the throttle body......when that throttle plate opens, it lets more "air" into the engine......even though it's called a gas pedal, it's really just an air pedal......a TPS(throttle position sensor) is attached to the linkage of the throttle plate......so when the thottle plate moves, so does the sensor.....the sensor "tells" the engine's computer how much the throttle plate is opening.......by knowing how much the throttle plate opens, the computer will give more gas to the engine, by holding the injectors open longer.....

With a TAC system, there is no cable between the pedal and the throttle plate.....instead, there is PPS(pedal position sensor), attached to the pedal......as the pedal moves, the sensor tells the engine's computer how much.......the computer then commands a motor in the throttle body to move the throttle plate to a position that corresponds to the same position of the pedal.......two throttle position sensors, tell the computer when the throttle plate has opened to the correct position......

So the old system used a cable to "manually" move the throttle plate.....the TAC system moves the throttle plate electrically.....

So if a problem happens with the PPS, or the motor in the throttle body, or one of the TPS sensors, OR, if there is a bad electrical connection anywhere in the TAC system, a code is set, and the engine will go into what is known as "LIMP" mode.....this is usually a reduced power mode where, engine's computer will not allow the throttle plate to move past a certain position, even if you push the pedal to the floor......sometimes, by stopping, shutting the car off, the problem "may" go away and the car drives normally.....sometimes it doesn't....

You say the engine was replaced......it's possible, the engine came from a junkyard, and maybe the top of the junkyard engine was damaged, or parts of the top of the engine may have been sold, and you just got the basic engine "block"....if this was the case, then parts from your old engine may have been transferred to the "new" engine.....now there is nothing wrong with doing that.....but if there was a previous problem with the TAC system, and parts of the TAC system were used on the "new" engine, then that problem never went away......it was just transferred to the "new" engine.......or it could be a harness problem or computer problem, that was still in the car....

As for: "the car would not crank back up. I had to get a tow to a mechanic who informed me that my engine was shot so I payed to have another used engine put in."

Was the engine making a noise before it died(like a knocking sound?)? When you say it wouldn't crank, do you mean the engine would rotate(turn over), but not start? Or that it would not rotate at all?

First off, unless you absolutely know this guy and trust him, you should always get a second opinion.....If a Tech says, the "engine is shot", that is a red flag for me......he better be telling me EXACTLY what is wrong with it, for example, that the engine seized because there was no or low oil in the car....but if that happened, and the engine was not making a knocking noise, I would question that......

Hopefully, the Tech was honest, and your engine was "shot".....but like I said, I would want to know what exactly was wrong with the car and the possible cause of it, before giving the go ahead on an engine replacement.....if that engine was not making any noises, wasn't overheating, and was running fine until you shut it off, it does make you wonder.....

[hannahpenn08]

Thanks for the reply. An answer to the engine questions...the mechanic informed me that there was no oil in the car when they looked at it and the pistons were rotating onto the other pistons which was bad because it was metal on metal. At first, when I tried to start the car, it made a clicking noise. I waited a little bit of time and tried to start it again but got nothing. No noise, was not even turning over. As time and more tries passed, the car did make a knocking sound and the computer system was messing with the radio and warning lights. They would come on then go off by themselves. The mechanic did try to get it started there by hooking it to a battery. I did watch that and nothing happened.