A few years back I bought a used 96 Grand Am 3.1L V6. Recently it started giving me an issue. It will idle just fine and in park, it will rev up properly. The problem starts on the road. It is pretty hard to describe what exactly it is doing, but I will try. When I press the accelerator, the engine doesn't rev up accordingly. It seems like there is a dead zone. It will go up to ~2k rpm and then won't rev anymore. If I press the accelerator more, it will eventually shift, but it doesn't seem to want to actually rev up while driving around. Not only that, but sometimes, when I press the accelerator (after coming to a stop) it won't rev up at all, and the engine will start to shake (maybe closer to vibrate). Now, it isn't coming from a tire or anything like that. It seems to be coming from the engine itself. When it starts shaking, it will drop some rpms (to below where it is while coasting) and won't go back up when the accelerator is pressed. The shaking will get worse with depression of the accelerator. The shaking doesn't happen very often, but when it does, I have to coast for a while before it will start actually accelerating again.
The things recently done to the engine include an oil change, the addition of transmission fluid (initially thought this problem was due to low transmission fluid, but even now with adequate fluid, it still has this issue), a new fuel filter, a new fuel pump (the fuel pump was changed not long ago and we thought it was faulty), new air filter, and a new throttle position sensor. Next on the list to check is the ignition coil pack. At this point, we are pretty frustrated that we can't fix the issue and are testing just about anything that might be causing the problem.
Also, after changing out something like the fuel filter, fuel pump, and throttle position sensor, as well as correctly the level of transmission fluid, the car would run correctly for a while. The shaking and unresponsiveness would then rear its head after about 30 minutes worth of driving. This doesn't mean that it only has this issue when the engine is hot, it just seems to wait until the engine is hot whenever we fix something. That might be important, it might not be. Any help would be greatly appreciated.
The things recently done to the engine include an oil change, the addition of transmission fluid (initially thought this problem was due to low transmission fluid, but even now with adequate fluid, it still has this issue), a new fuel filter, a new fuel pump (the fuel pump was changed not long ago and we thought it was faulty), new air filter, and a new throttle position sensor. Next on the list to check is the ignition coil pack. At this point, we are pretty frustrated that we can't fix the issue and are testing just about anything that might be causing the problem.
Also, after changing out something like the fuel filter, fuel pump, and throttle position sensor, as well as correctly the level of transmission fluid, the car would run correctly for a while. The shaking and unresponsiveness would then rear its head after about 30 minutes worth of driving. This doesn't mean that it only has this issue when the engine is hot, it just seems to wait until the engine is hot whenever we fix something. That might be important, it might not be. Any help would be greatly appreciated.
