Engine Hesitation?

Hi and thanks for using 2CarPros.com.

This could be several things. If the check engine light is on, have the computer scanned to determine trouble codes and possible solutions to this problem.

If there is no check engine light, I would start by checking fuel pump pressure. If the pressure is low at first, it can cause the symptoms you described.

Here are general directions for checking fuel pump pressure:

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

and

https://www.2carpros.com/articles/engine-hesitates

The pressure specifications are:
Engine NOT running 60 - 66 psi at 0 rpm
Note: Check pressure with the key "on" and the engine not running.

Do this and let me know what you find.

Take care,
Joe

Have you checked for vacuum leaks? Has the check engine light come on? Have you tested fuel pump pressure?

Let me know.

Joe

IF the check engine light is on at times, there will be a trouble code stored in the computer. Take the vehicle to a nationally recognized parts store and have them scan the computer. Most will do it for free, so there is no money out of pocket for you. After they identify the code, you should know what the problem is. Let me know what you find so I can help you with further questions.

Joe

Thanks for the donation

The following could cause your problem:

Dirty fuel injectors (cleaning the injectors often fixes this).
Bad MAP (manifold absolute pressure) sensor
Bad TPS (throttle position) sensor
Bad or dirty MAF (mass airflow) sensor
Low fuel pressure (leaky fuel pressure regulator or weak fuel pump)
Vacuum leaks (intake manifold, vacuum hoses, throttle body, EGR valve)
Bad gasoline (fuel contaminated with water or too much alcohol)

Sometimes, what feels like a hesitation is actually ignition misfire rather than lean misfire. The causes of ignition misfire may include:

Dirty or worn spark plugs
Bad plug wires
Weak ignition coil
Wet plug wires

Did you use AC Delco plugs and wires? If not, change to AC Delco. Any other brand will not work and/or help. Â If there are no vaccume leaks and the PCV valve is not sticking, then it sounds like the the timing is off a little and the distributer gear may be worn. This is a commonly overlooked problem. You can take the distributer out to check or have the timing checked. Remember, the timing on your engine must be checked at operating temperature and with a scan tool -- a timing light will not work.

This guide can help.

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

Please run down this guide and report back.

The place to start is by having the diagnostic fault codes read and recorded. The people at many auto parts stores will do that for you for free. The problem is though, a sensor reading has to go outside of a specific voltage range for a code to set. That sensor can sometimes report the wrong value but one that is acceptable to the Engine Computer. In that case your mechanic will have to look at live data on a scanner to see what doesn't look right.

Another thing to consider is a vacuum leak or a leak in the fresh air tube between the air filter box and the throttle body. Every manufacturer other than Chrysler uses a mass air flow sensor to measure the weight of the incoming air. A leak anywhere that lets air sneak in without being measured will result in no gas to go with it. That will cause a lean condition and typically a hesitation. Once the coolant temperature reaches a certain point, the system goes into "closed loop", meaning the computer adds the oxygen sensor readings to its list of things it uses to calculate fuel metering. That can result in the computer requesting extra fuel to get the lean mixture back to where it should be, and the hesitation will be gone.

Hi
Check engine light on? Could be two problems one stumble maybe MAF try cleaning. Cold start temp sender ECT near thermostat housing.
Let me know
Thanks for donate

Cloged CAT is not likely with your symptoms. What about MAF and temp sender?

Spray starter fluid into intake and if it starts then the fuel pump probably died.