Acceleration hesitation in O4-cylinder 2002 Chevy

ANSWER : Hi, thanks for writing in. Sorry to hear of your difficulty with your 2012 Sonic. The good news is your Check Engine Light is on, so what means the fault has been "recorded" by the engine computer and diagnostic codes will be available to the mechanic to search for the fault. The codes don’t necessarily indicate which "parts" have failed but rather will indicate which systems are malfunctioning and causing poor operation of the engine. Individual components in these systems will then have to be tested by the mechanic. The traction codes may or may not be related to the issue with the engine, the poor acceleration, but those traction codes will have to be evaluated as well. It is possible there is more than one problem. If you would like help, consider having an expert automotive technician from YourMechanic come to your home or office to inspect your vehicle for you and download codes your car computer has stored, and make or suggest any repairs as needed.

ANSWER : If you find that when you step on the gas and your RPM takes up, but the car doesn’t follow, the transmission is slipping. Unfortunately on that, it’s a very expensive job rebuilding the transmission. So what you’re going to do is try to change the fluid filter, and put some good Lucas automatic transmission additive and pray you don’t need a transmission overhaul, because it’s a very expensive job on that car. If you would like to have this checked out in person, a technician from YourMechanic can diagnose your car’s hesitation issue so that you know exactly what repair is needed.

ANSWER : Unmetered air can cause this type of hesitation and shuddering. Too much air compared to fuel will cause a lean misfiring condition. Fault codes need to be read out of your Mercedes C320’s engine computer to see if there are any underlying issues and those issues are corrected.

The induction should be inspected and checked for vacuum leaks. Also, fuel pressure and volume should be checked as well if the induction system checks out okay. A partially clogged fuel filter can cause a starvation issue on heavy acceleration. You may want to enlist the help of a mechanic, such as one from YourMechanic, who will have the tools and expertise to conduct this type of diagnosis and repair for your acceleration issue.

ANSWER : Hello and thank you for your question. With having your engine with bank 1 being lean (lack of fuel), the symptoms are showing that there is a problem with fuel delivery or excessive heat. If the EGR valve was to be stuck open, the engine will get more burnt fuel into the cylinders and cause them to heat up making the computer back off the fuel until needed.

The MAF sensor tells the computer how much air is coming in the engine. The MAP sensor tells the computer how much pressure is on the manifold. The throttle position sensor tells the computer where the throttle plate is located at.

If you are getting a code for bad connection between all of these sensors, then there is a bad ground connection or the harness to the vehicle is broken somewhere. The ground to the sensors are in the computer and the throttle pedal. So if the ground is the problem, then you would need to replace the computer or throttle pedal or both. Check all of the harness plugs to all of the sensors and use a digital volt meter to check for power to all the sensor harness connections using a paperclip. Then check all of the ground circuits with resistance. If you have some resistance but not a lot, then the circuits are okay. If you have no resistance, then the ground circuits are broken somewhere between the harness plugs and the computer or pedal. I would recommend having a professional diagnose the hesitation issue and move forward with appropriate repairs.

ANSWER : First thing that you want to do is check the tie rods, when they wobble when you move them, then it is often bad tie rods. So it could be as simple as bad tie rods. If your tie rods are really worn they can also make a rubbing noise when you turn to the left, too. If you need help, have a technician, such as one from YourMechanic inspect your car’s shaking issue. They will be able to make a diagnosis and follow through with repairs that you need.

ANSWER : This may be related to many different things that can cause the engine to struggle. One possibility may be a sign of a clogged catalytic converter. As you may already know, the catalytic converter converts toxic exhaust gases into less harmful pollutants that are suitable to be expelled into the atmosphere. When this is clogged, this causes these gases to be backed up into the exhaust system not allowing the engine to breathe properly (think of a backed up sink). When this happens, the engine is forced to work much harder to expel these gases. This often results in the engine bogging down, hesitating, shaking and causing very poor fuel economy. Typically when this happens it may also cause the catalytic converter to become very hot and in some cases turning bright red. This should also cause a check engine light to come on as the O2 sensors should be reading the incorrect amounts of oxygen in the exhaust gases if this is your problem. I would recommend having an expert from YourMechanic come to your location to diagnose and replace your catalytic converter.

ANSWER : You don’t mention the Check Engine Light being on, but if so, check trouble codes before any other diagnostic activity – usually saves time! Good call on your initial repair – oil in the spark plug well can short the spark plug, causing a "miss" from that cylinder. It’s possible you have a bad ignition coil (or more), or some other problem like a blown head gasket causing one or more cylinders to misfire. A professional mechanic, like a certified technician from YourMechanic, can check for good spark, good compression, and proper fuel injection on each cylinder to isolate the problem and make repairs.

ANSWER : Hi there. What were the diagnostic results? What were the data readings from the ECM? What diagnostic process did you use to determine the other parts were in need of replacement? These are the questions that I ask anytime I am presented with a unique concern such as this one. Compare data reading to factory specs before replacing any parts; air flow meters can be presenting incorrect readings that are not considered faulty readings. The ECM will simply adjust fuel trim to compensate. Of course, the meter may not be changing the reading at all from idle; imagine how the ECM will react to increased throttle opening with an airflow reading that matches idle speed (lots of throttle and no air) or increased airflow without an increase in throttle position if the TPS is faulty (lots of air and no throttle). I suggest having a qualified technician perform an inspection to avoid replacing unnecessary parts. Your Mechanic has several available technicians that can assist you with a car has low power inspection.