Car is misfiring and has a lack of power

So i just put in a used motor. Pretty much everything is new. When its cold started it idles at 1,000 rpm and dosnt go down until u shift into reverse or drive. When u step on the Gas the rpms drop and chugs and finaly starts moving. I set timing and spark plugs are in order. There is no vaccum leaks.
My car has an automatic transmission.
Experienced mechanics share their insights in answering this question :
It is very difficult to definitively say what the issue is. Have you had the vehicle scanned for diagnostic troubleshooting codes? If not, you should start there. Due to your vehicle being pre-1996, the method of receiving codes will be more difficult. You should look to your owners manual for that procedure. Hopefully, the issue will have set a code and will make diagnosis a lot easier.

If this is a misfire, its likely a code is pending. Chances are, this is a problem relating to the air fuel mixture entering the engine when the vacuum changes after entering a gear. If you are certain there are no issues with the vacuum, look to the throttle body, fuel injectors, and valves.

If you need some assistance with these checks, consider YourMechanic, as one of our mobile technicians can come to your home to diagnose the misfire firsthand and help you fix it accordingly.

How to Identify and Fix Common car Problems ?

Our sources include academic articles, blog posts, and personal essays from experienced mechanics :

From the spark plugs to the ignition coils, many different things can cause an engine to misfire. The most common causes of misfires are worn, improperly installed, and mishandled spark plugs, malfunctioning ignition coils, carbon tracking, faulty spark plug wires and vacuum leaks.
If your GM truck occasionally loses the ability to accelerate and warns you of reduced engine power, that could be caused by a faulty throttle body. While not common, this issue can interfere with your engine function and cause your vehicle to lose power anywhere from once in a while to several times in a day.
The main reasons why your Chevy truck might be losing power when accelerating are low engine compression, clogged fuel or air filter, faulty fuel pump, and so on.
A flashing Check Engine light and a P0301 to P0312 diagnostic trouble code is a sure-fire indication that one or more cylinders are misfiring. Occasional misfires may pass unnoticed, but a steady misfire is hard to miss. The engine usually feels rough, lacks power and uses more gas than usual.
If an oxygen sensor or mass airflow sensor is failing, it could give incorrect data to your engine`s computer, causing the misfire. When a vacuum line is broken, it can cause a fuel-injected motor to misfire.
There are several causes for your car to lose power significantly while accelerating. The most typical causes of a car not accelerating while driving include a faulty sensor, contaminated fuel or air filters, or a faulty timing belt. Generally, this isn`t something you should ignore.
Clean air filters and fuel injectors will reduce the strain on your car. An engaged emergency brake causes the brake to drag slowing down your car. Disengage the brake to solve this issue. Sometimes acceleration problems are just because of low fuel or poor quality of fuel.
There are several reasons the Chevy 350 bogs on acceleration, including problems with the ignition system, fuel pump, air filter, catalytic converter, or muffler. The most common cause is that your Chevy 350`s fuel filter is clogged or the pump isn`t working properly.
The most likely issue is that a component is clogged. A clogged fuel filter is the most common reason, although a loss of power in your car could also indicate problems with the fuel pump or fuel line. Impurities or debris may be blocking the system, which causes the loss of power in a car.
Possible causes of a power failure could be either bad battery connections, a bad ignition switch, or a bad alternator. What you need to do is check your vehicle`s power sources.
A Bad Crankshaft Position Sensor

The crankshaft position sensor monitors the position and rotational speeds of the crankshaft. Without the crank sensor, the engine control module (ECM) wouldn`t know when to fire the fuel injectors and ignite the spark plugs.

Once a timing chain is stretched and has lost its integrity, the chain may skip a gear and lose the necessary coordination leading to an engine misfire. Repeated misfires could indicate a timing chain issue and should be investigated.
Even a dirty MAF sensor can cause a lean code and/or misfire to occur. The engine may be stalling because it isn`t getting enough throttle opening.
your engine misfires and shakes: if a map sensor reports a false high pressure reading, the engine`s computer will signal for more fuel. this results in a rich mixture, which can foul the spark plugs and cause a cylinder not to fire. a misfiring engine will shake and transmit that motion into the cabin of the vehicle.
An engine misfire can be caused by bad spark plugs or imbalanced air/fuel mixture. Driving with a misfire isn`t safe and can damage your engine.

Relevant Questions and Answers :

the most relevant questions and answers related to your specific issue

Power steering loss, no belts are turning but the car is running fine. I also have a soft pedal. Whats wrong with my car?
ANSWER : I have only seen this situation once in my 30+ years and it turned out to be a broken crankshaft pulley. Belts are driven by the engine. The crankshaft pulley spins the belts, which in turn spin the air conditioner compressor, power steering and water pumps, and the alternator. The vehicle should be towed to your local repair shop and not driven. Without the water pump spinning to circulate the coolant, the engine will quickly overheat and result in more extensive damage.

I put the wrong key in my car and a few weeks later my car just shut down and it will not start I believe it’s the computer but…
ANSWER : Hi there. What had happened is the wrong key set the security to the vehicle. This is to prevent the vehicle from starting with the wrong keys. Try removing the battery cables (+) and (-) for 13 minutes. During that time, put the original key in the ignition and turn it on. Activate everything in the car even though there is no power. Then remove the key and hook up the battery cables. The computer should have reset and reset the security. If the security is still being tripped, then I recommend seeking out a professional, such as one from Your Mechanic, to help you

Replaced alternator on car 2 times each time shows it’s charging 14v let car run for a little bit then test drive and car voltage
ANSWER : There are reports that the replacement alternators will not communicate with the engine computer and will not charge correctly. I recommend using only the manufacturer approved replacement part. It can be new or remanufactured but approved for use in the vehicle. Some lower cost alternators on the aftermarket will have charging problems since they will not communicate with the ECM on the vehicle and will stop charging.

Can i drive my car even when the "engine power loss" alert turned on?
ANSWER : Hi there. A Reduced Power light usually indicates a fairly serious problem with the throttle system. When this light illuminates the vehicle will often go into a “safe mode”, which will severely limit the speed of the car and in some cases will render the vehicle non-driveable. Since the Reduced Power light can trigger for a number of different reasons, tracking down the exact cause is extremely important, if the vehicle is not properly diagnosed and repaired, the Reduced Power light will trigger again, putting the vehicle in safe mode. I would recommend having a professional mechanic come to your location and complete a reduced power light inspection.

No power. Only uses bank 2 to fire
ANSWER : Hi there. It would be helpful to know the year of the car in this case to supply the most accurate information. If it were the map sensor, then it would affect all cylinders. Try checking the spark plugs for damage or signs of wear.

Which timing was off, ignition or camshaft timing? I’m going to assume it was the camshaft timing since modern vehicles don’t typically have adjustable ignition timing. Assuming it is camshaft timing, it is very likely the valves in the inactive cylinders have been bent. You can check this by putting compressed air into the cylinder with the piston on top dead center.

This is commonly called a cylinder leak down test. Ideally you should only use about 50 psi. Much more and the piston will move and open the valves. The valves need to be closed for this test to be accurate. If you must use shop pressures of 90 to 150 psi, hold the crankshaft by whatever method you can devise.

Once you have the piston at top dead center with compressed air in the cylinder, listen at the tail pipe, intake manifold with the throttle valve open and in the crank case. Usually the best place to listen in the crank case is by removing the oil filler cap. You are listening for the hissing sound of air passing past the intake and exhaust valves or the piston rings in the case of the crank case. If you here an obvious hiss, you have a leak in one of the mentioned parts.

Bent valves are very common when camshaft timing becomes off. This car has VVT (variable valve timing). With this in mind you should make sure that the camshaft is timed correctly.

If you should require further help getting this taken care of, have a certified professional diagnose the loss of power issue for you so that this can be properly addressed.

Car won’t start, no power, doesn’t even crank engine.
ANSWER : Hello, thank you for writing in. When it comes to the vehicle not starting, and not having electrical power, always start by checking the battery. In your situation you can go remove the battery from the vehicle, and take it to have it tested. If it is bad, simply replace it and drive the care home. During this process make sure the battery cables, ground connection, and connection to the starter are all clean, dry, and tight. If the battery is not bad, then you may have an ignition cylinder issue. This may come in the form of a connection issue, or some kind of other mechanical failure. There may also be a problem with the starter. Only further testing will tell. For more help resolving the issue, contact our service department and they may be able to help you where the vehicle sits now.

The car has no power, the ignition relay keeps making a clicking noise, and the car won’t start
ANSWER : I suspect you have a dead (or very low) battery, a failed alternator, and an electrical circuitry problem as well. It may be hard to tell which came first if there is wiring damage already. The clicking you hear is likely the starter solenoid not getting enough power because of a dead battery.

If the car shut down while driving, that is usually an indicator that the alternator is not charging the system. Once you have jumped it off, it should continue to run on the alternator. The failure to run more than 10 mph and the smoke from the engine compartment suggest very low system voltage and additional wiring problems sapping all the electrical system’s power.

I would recommend having a professional mechanic, such as one from YourMechanic, perform an inspection to determine why the battery will not hold a charge and assess any additional problems with the alternator.

My car is having power issues. I get a message that says engine power reduced/ service traction along with headlights flickering and engine cutting out.
ANSWER : Hi there. Check the battery and alternator to the vehicle. With all of the electrical issues that you are having, it sounds as if the battery is not charged and making the engine stall out due to lack power. Check the battery for a 12.6 volt reference and load test the battery. If the battery fails, then replace the battery. If the battery passes, then check the alternator and see if its putting out the full amount of amps. If you need further assistance with electrical issues, then seek out a professional, such as one from Your Mechanic, to help you.