Why does my engine have low power it will not accelerate?

Good morning,

No, there is no blown fuse.

Is the check engine light on? If it is, do you know the code?

https://www.2carpros.com/articles/how-to-test-a-catalytic-converter

It sounds to me like your catalytic converter is clogged not allowing the engine to breathe.

https://www.2carpros.com/articles/engine-has-low-power-output

Roy

Car sometimes does not want to accelerate. I have to let go of gas while driving in order to catch again.

Welcome to 2CarPros.

Have you checked fuel pump pressure? What you described sounds like it is starved for fuel. It could be as simple as a partially plugged fuel filter or a weak pump. What I recommend first is to check fuel pressure to confirm it is within the manufacturer's specs.

Here is a link that explains in general how it is done:

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

Here are the directions specific to your vehicle. They include the manufacturer's specs for pressure. However, they also include info related to a bleed down test which isn't the issue. The attached pics correlate with the directions.

____________________

2013 Hyundai Sonata L4-2.4L
Component Tests and General Diagnostics
Vehicle Powertrain Management Fuel Delivery and Air Induction Fuel Pump Fuel Pressure Testing and Inspection Component Tests and General Diagnostics
COMPONENT TESTS AND GENERAL DIAGNOSTICS
Fuel Pressure Test

1. Release the residual pressure in fuel line .

CAUTION:
When removing the fuel pump relay, a Diagnostic Trouble Code (DTC) may occur. Delete the code with the GDS after completion of "Release Residual Pressure in Fuel Line" work.

2. Install the Special Service Tool (SST).
(1)Disconnect the fuel feed tube from the high pressure fuel pump.

CAUTION:
There may be some residual pressure even after "Release Residual Pressure in Fuel Line" work, so cover the hose connection with a shop towel to prevent residual fuel from spilling out before disconnecting any fuel connection.

(2)Install the special service tool for measuring the fuel pressure in between the fuel feed tube and the high pressure fuel pump .


pic 1

3. Inspect fuel leakage on connections among the fuel feed tube, the high pressure fuel pump, and the SST components with IG ON.
4. Measure Fuel Pressure.
(1)Start the engine and measure the fuel pressure at idle.

Fuel Pressure:445 - 455 kPa (4.5 - 4.6 kgf/cm2, 64.5 - 66.0 psi)

NOTE:
If the fuel pressure differs from the standard value, repair or replace the related part .


pic 2


(2)Stop the engine, and then check for the change in the fuel pressure gauge reading.

Standard Value:The gauge reading should hold for about 5 minutes after the engine stops

NOTE:
If the gauge reading should not be held, repair or replace the related part .


pic 3

(3)Turn the ignition switch OFF.
5. Release the residual pressure in fuel line .

CAUTION:
When removing the fuel pump relay, a Diagnostic Trouble Code (DTC) may occur. Delete the code with the GDS after completion of "Release Residual Pressure in Fuel Line" work.

6. Test End
(1)Remove the Special Service Tool (SST) from the fuel feed tube and the high pressure fuel pump.
(2)Connect the fuel feed tube and the high pressure fuel pump.

Fuel Pressure Test

1. Release the residual pressure in fuel line .

CAUTION:
When removing the fuel pump relay, a Diagnostic Trouble Code (DTC) may occur. Delete the code with the GDS after completion of "Release Residual Pressure in Fuel Line" work.

2. Install the Special Service Tool (SST).
(1)Disconnect the fuel feed tube from the high pressure fuel pump.

CAUTION:
There may be some residual pressure even after "Release Residual Pressure in Fuel Line" work, so cover the hose connection with a shop towel to prevent residual fuel from spilling out before disconnecting any fuel connection.

(2)Install the special service tool for measuring the fuel pressure in between the fuel feed tube and the high pressure fuel pump .


pic 4

3. Inspect fuel leakage on connections among the fuel feed tube, the high pressure fuel pump, and the SST components with IG ON.
4. Measure Fuel Pressure.
(1)Start the engine and measure the fuel pressure at idle.

Fuel Pressure:480 - 520 kPa (4.9 - 5.3 kgf/cm2, 69.6 - 75.4 psi)

NOTE:
If the fuel pressure differs from the standard value, repair or replace the related part .


pic 5


(2)Stop the engine, and then check for the change in the fuel pressure gauge reading.

Standard Value:The gauge reading should hold for about 5 minutes after the engine stops

NOTE:
If the gauge reading should not be held, repair or replace the related part .


pic 6


(3)Turn the ignition switch OFF.
5. Release the residual pressure in fuel line .

CAUTION:
When removing the fuel pump relay, a Diagnostic Trouble Code (DTC) may occur. Delete the code with the GDS after completion of "Release Residual Pressure in Fuel Line" work.

6. Test End
(1)Remove the Special Service Tool (SST) from the fuel feed tube and the high pressure fuel pump.
(2)Connect the fuel feed tube and the high pressure fuel pump.

_________________________________

If you find the fuel filter or the pump is the issue, here are the directions for replacement. Note that to replace the filter, you have to remove the fuel pump from the tank. Note, if you have to replace the fuel pump, make sure to do the filter at the same time.

2013 Hyundai Sonata L4-2.4L
Removal and Replacement
Vehicle Powertrain Management Fuel Delivery and Air Induction Fuel Filter Service and Repair Removal and Replacement
REMOVAL AND REPLACEMENT
Replacement

1. Remove the fuel pump .
2. Disconnect the electric pump wiring connector (A) and the fuel sender connector (B), and then remove the fuel sender (C).
3. Disconnect the fuel tube quick-connector (D).
4. Remove the head assembly (E) after releasing the fixing hooks.


pic 7

5. Disconnect the fuel feed tube quick-connector (A).
6. Remove the fixing clip (B), and then disconnect the fuel tube (C).
7. Remove the reservoir-cup (D) after releasing the fixing hooks.


pic 8

8. Disconnect the ground cable (A).
9. Remove the cap (B), and then remove the assist pump (C) and the fuel pressure regulator (D).


pic 9


CAUTION:
Be careful of O-ring.

10. Separate the electric pump motor from the fuel filter after releasing the fixing hooks (A).


pic 10


pic 11



pic 12

1. Head Assembly
2. Electric Pump Motor
3. Fuel Filter
4. Fuel Sender
5. Fuel Pressure Regulator
6. Assist Pump
__________________________________________

Here are the directions for removal and replacement of the pump assembly.

2013 Hyundai Sonata L4-2.4L
Fuel Pump
Vehicle Powertrain Management Fuel Delivery and Air Induction Fuel Pump Service and Repair Removal and Replacement Fuel Pump
FUEL PUMP
Removal

1. Release the residual pressure in fuel line .
2. Remove the fuel pump service cover (A) in the trunk.


pic 13

3. Disconnect the fuel pump connector (A) and the fuel tank pressure sensor connector (B).
4. Disconnect the fuel feed tube quick connector (C) and the vapor tube quick-connector (D).
5. Remove locking ring (E) by use the special service tool [SST No. : 09310-2S200].


pic 14

6. Disconnector the vapor tube quick-connector (A) at the fuel pump, and then remove the fuel pump from the fuel tank.


pic 15



pic 16



Installation

1. Installation is reverse of removal.

CAUTION:
Be careful of fuel pump direction.

_________________________________________

Let me know if this helps or if you have other questions.

Take care,
Joe

Car will not accelerate past forty mph and rpm's will go up and car will not shift at forty mph. Malfunction light is also lit.

It sounds like you have a weak fuel pump, clogged catalytic converter or a bad MAF or MAP sensor but to be sure we should run the codes by checking out this guide.

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

we should also go over this guide as well.

https://www.2carpros.com/articles/engine-has-low-power-output

Please run down these guides and report back.

Hello PBFENERGY,

I am sending you a link to an article that features written step by step instructions and pictures explaining how to scan for codes yourself. Also, I have included a link to our YouTube channel with a how to video on code scanning.

This is applicable even if your check engine light is not on.

Most scanners are inexpensive to purchase, you can purchase one online from sites like Amazon.com

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

https://youtu.be/YV3TRZwer8k

Once you have the codes please get back to us so that we can further assist you. We are always happy to help.

Thank you for visiting 2CarPros.com.

Kindest regards,
Renee

Admin

Car listed above is the GLS model.I Changed full synthetic engine oil, filter and air filter 12/17, rotated tires. Drove a bit locally without issue. On 12/20, it was raining, the car did not accelerate properly when entering highway. After about 20-30 miles/hr, pressing down the pedal won’t accelerate further. When press pedal all the way to the bottom, still not acceleration and the engine speed is just 2000 to 3000 rpm. When depress the pedal can feel the car choke a bit. On the way back via local, couple times it did accelerate to about 40-50 miles/hour, if I slowly and gently press the pedal. The temperature looks normal. Engine light is off, so are other lights. The car just passed its 150,000 miles mark. Any suggestions what could go wrong? Transmission? Brake pedal stopper?  others?

Hi,

Interestingly, when you press on the throttle, you seem to have less power. Often times that is caused by a weak fuel pump. When you press the throttle, the engine requires more fuel.
If it isn't available, what you described can happen. Since it was running okay after the oil change, that is the first thing I would check. Here is a link that explains how to check pressure:

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

Here are the manufacturer's specs for pressure:

Standard Value: .................... 345 - 355 kpa(3.51 - 3.61 kg/sq.cm, 50.0 - 51.5 psi)

_________________________

My next question is this. I have seen situations where the catalytic converter has come apart internally and the guts move around, usually making a rattling sound. What can happen in this case is when the engine begins to rev, the guts restrict air flow and the vehicle experiences power loss. If you question this, take a rubber mallet and tap on the exhaust to see if there is any noise coming from the converter. Also, here is a test for checking for converter issues:

https://www.2carpros.com/articles/how-to-test-a-catalytic-converter

Here is a link explaining common symptoms of a catalytic converter issue. See if anything seems to mirror what you experience.

https://www.2carpros.com/articles/bad-catalytic-converter-symptoms

Let me know what you find. Also, let me know if you have other questions.

Take care,
Joe

Hi JACOBANDNICKOLAS,

Thank you for your time and suggestions. I checked couple things last night and the car somehow become running normal again. I will describe the details so not miss anything. Even though it seems runs again I still like to figure out what was wrong and fix it, so it does not come back again.

I checked the code although no engine light. No code. When I turn the key to on position the hissing sound was like before, indicating the fuel pump works at least, and maybe normally.

Turned the key to start, and found that the battery was low, so the engine is cranking but wont start, even when I pedal on for about 10 seconds. This reminds me (I forgot to mention) that on 12/20 when it did not accelerate properly, the battery was also low at start, but the engine was able to start when pedal on for a few seconds, and I drove out without waiting for the battery to be charged. I used the jump starter and the car started right away. When the car starts from cold it always has some cyclic grinding sound for a few minutes around crankshaft and camshaft, that I was believing to be due to the interference at cold temperature. This time I opened the hood and try to see if there is anything abnormal in that region. The car was running for about couple minutes and the grinding sound diminished as in the past.

I then stopped the engine. The battery red pole has no build up. I checked the air filter counter part. No debris from the air filter to the engine as I can tell, although I can not see the air entrance to the engine. The pipe seems clean. I removed the air mass flow sensor, and it looks clean too.

I need to get a fuel pressure gauge to measure the fuel pressure, and plan to check the catalytic converter the same time when I jack up the car. So last night I turns on the engine again without the jumper, and it started right away. I drove it out and everything becomes normal… I tried accelerate to 60 miles/hr and there is no hesitation of acceleration.

So the battery is my culprit and here is my theory. On 12/20 I marginally started the car with a low battery and immediately went on the road. The battery was still low, while I turned on the head light, the AC heater & defrost to high power, and also the stereo. The battery was barely charged when the car hit high way. So when I pedal up to enter high way, the battery cannot provide the power to the fuel pump to get more gas to the engine. Today when I went to O'Reilly I will also ask the battery be checked out, and probably get a replacement battery if confirmed. I will update when back from the store.

What do you think?

The battery is bad. The alternator is good. Replaced the battery and it drives good. I will drive and see for a few days. Thank you for the help so far.

At this point, I suspect you are correct. A weak battery on today's cars can play havoc with the electronics. See if it continues to run normally. However, I do have a question. Do you mean you have to press the accelerator to start the engine? If that is the case, you may have a bad fuel pressure regulator. That would be checked when checking fuel pressure. It may just be too high and feeding too much fuel to the engine. When you press the throttle pedal to the floor, it basically shuts down the injection to prevent flooding.

Let me know.

Joe

My son's car will sometimes lose power while driving. It doesn't die, but it won't accelerate. He pulls to the side of the road, turns it off and then back on again and it works fine. When it happens the check engine light comes on and after he turns it off and back on again, the check engine light goes off.

I have a 2006 Sonata limited V6. I have experienced a similar problem. It happens intermittently. When I am passing, I accelerate the engine revs (as if it is in neutral) and there is no acceleration and in most cases the check engine light comes on. This has been happening several times between 30,000 and 71,000 miles. I have taken it to the dealer each time. They replace a MAP sensor, wire harness, or other component and claim it has been fixed.

HI i have taken code from computer they are as follows: 2106, 1295, 2135. i need the problems for these codes and any information.

Hi All codes are for faults in Electronic Throttle Control to determine if replacement is needed a diagnostic scan of codes will be needed. Location see diagram

Hope this helps Thanks for donate

The check engine light came on then a knock then a loss of power, When I stopped the car the engine was knocking and shaking violently. Is this a timing belt tensioner.

if it's aknock i dont' think so. have apro listen to this as it's very hard to diagnose, but sounds like something major

I dont like magor saw somewhere it could be an egr so am hoping it is not to bad

we really can't hear it so we have to suspect major with aloss of power. If it is aheavy knowck then it wouldn't be an egr valve

it is heavy heavy might have the timming chain done to cant get it on a code reader had to tow it home did not want to tear it up worse. Thank you and I will let you know what they find out

I have replaced the following items:
1. Camshaft position sensor.
2. Engine wire harness.
3. Upstream O2 sensor.
4. Fuel pump.
5. Injectors.
6. Coils.
7. Spark plugs and wires.
8. Misfire sensor.

I have also cleaned the Idle Air Control and the throttle body.

I am at my wits end, what else can I do?

Hi and thanks for using 2CarPros.com. You have already done a lot of work and eliminated many of the possible problems. However, I have to ask if you checked engine timing as well as the catalytic converter to see if it is plugged.

To start, here are general symptoms of a plugged converter:
https://www.2carpros.com/articles/bad-catalytic-converter-symptoms

Here are general directions to check one:
https://www.2carpros.com/articles/how-to-test-a-catalytic-converter

As well as a video:
https://youtu.be/kNXh1Lphzr4


I realize the ignition timing is controlled by the PCM, but here are the specs for where it should be. (see attached picture 1)
In addition, there is a ignition adjustment cable you should check if timing is an issue. Make sure it is getting power, is clean and tight, and no damage to the wiring. See attached pictures for location. I have also attached pictures of many of the sensors located under the hood because if the converter and timing check good, I want you to get a live scanner and check the coolant temperature sensor. (CTS). It tells the PCM the engine's temperature and from that, the computer adjusts air and fuel mixture. If it is too rich or lean due to an inaccurate reading, it will cause drive-ability problems.

I hope this helps. Let me know if you have other questions as well as what you find.

Take care,
Joe

i have a 2004 hyundai sonata 5 spd manual trans. the problem is that its arcing from where my spark plugs are located. i have replaced my spark plugs, the wires and i have used dielectric grease. i also tried it with other coils but it still keeps arcing. i have tried everything i could think of. it sparks only when i accelerate from the engine. i really don't know what to do.

What size engine do you have? What kind of spark plugs did you use? Did you gap them depending on type of plug? SPECIFICATION: 0.039-0.043 (1.0-1.1mm) over gapped plugs will cause the high voltage to take the path of least resistance. Talk to you soon, TY

Thanks for your answer. I have some auto lite double platinum spark plugs in it I gapped the at 0.044 because that's what the guys at autozone said it had to be. As I mentioned before I already tried other coils, spark plug wires, and spark plugs but it still arcs and its every time I accelerate from the engine. The engine is a DOHC 16 valve 2.4L.

Is there any oil down any of the four spark plug tubes? If not you may have what is called carbon tracing. This carbon trace conducts electricity and provides a shorter route to ground than the spark plugs do.
Can you see were it is arcing? or isolate which cylinder is arcing?
Let me know,TY

It arcs from the coils but sometimes it runs thru the wires. Like I mentioned to you before I replaced wires, spark plugs and even tried other coils but kept doing the same thing. You could hear the current running thru the wires

Can you see the arc occurring?
Does the engine run rough at idle or when accelerating?
Is there a check engine or service engine soon light on when cycling the key and with the engine running?

When it is dark outside (it is easier to see arcing when it is dark) run the engine and spray some water on the coils with a spray bottle (mist) you should see a bluish arcing whenever the coil discharges. Try this then get back to me, TY

Yeah I can see the electric discharge. My car on neutral is at 800 rpms about. When I accelerate and the rpms reach 1000 my car hits them rough. There is no lights on the dash. I took it to a mechanic to get it scanned but he said he got no codes. Also every time I turn my a/c on my car shakes heavily and drops to 500-600 rpms.

The only possible causes of electrical leaks could be: over gaped spark plugs, defective spark plugs, spark plug wires, and defective ignition coil. These are the only possible sources for arc to come through and ground out. So, one or more of the above components has got to be causing the arcing. Talk to you soon, TY

The current jumps from my coils but i already tried others but it did the same. I am going to try and regap my spark plugs. They are brand new but they just might be gaped wrong. I used an old gaping tool (worn a bit down). Thanks for your advise :)

Hi, sorry to bother you, but I am tired of the guessing games with my car. I have put a fuel pump in, checked spark plugs ( all are firing), put wholes in the catalytic converter, took the whole converter off and cleaned it out, and we have cleaned the injectors. But I still have no power when it cranks up sometimes it dies, but when you put it in reverse it will die sometimes when you put it in drive at first it might go five or ten mph for like the first ten minutes going down the road it will eventually pick up to about forty or forty five mph but hardly ever over that when you try to give it more gas it bogs down going up a hill, yeah it just does not happen at all.

Use a fuel pressure gauge to check the fuel pressure (post it here, please). Fuel pressure should read 46 - 49 psi at idle. If the fuel pressure is low it could result in the condition you have described.

Will not accelerate after warm up, it bogs and shuts off.. No DTCs! Cannot attain 3,000 rpm. Crank, cam, and knock sensors, okay. New coils, plugs, wires, ballast resistor, O2 sensors, fuel and air filters.

Dsims6465

At this age and mileage, the next thing that I would do is to check the fuel pressure. You can borrow a pressure gauge from AutoZone or whatever parts store is nearby. There is a valve that it connects to on the fuel rail. Find the fuse for the pump and pull it. Then try starting the car a few times. Maybe 10 times actually. This relieves the pressure. Then connect your gauge. Now put the fuse back in. Turn the key on and off about 10 times, but do not start the car yet. Leave the key on. Record the pressure.

Now start it and record the pressure again. Record the pressure again when it starts hesitating and dying.

Report those numbers here and I'll look up what it should be. I'd go ahead and get those numbers, but my 3 year old just woke up from his nap and he's angry.

Thanks for the try, but this is not a fuel pressure problem. And the fuel pump has been changed twice with new units. When warm the car will not rev up in neutral! And the problem is somehow temp related. When cold, the car is drivable. Also, the ECU, MAF, CKP, and CMP sensors have been changed. Nothing has changed the behavior.

It sounds like the catalytic converter can be clogging when warm but to confirm the issue lets go over this guide to see

https://www.2carpros.com/articles/how-to-test-a-catalytic-converter

Please run down this guide and report back.

For the past six months I have had acceleration problems in 2001 Sonata. I had the spark plugs replaced about three months ago and all that did was stop the car from shaking like crazy. Also when I accelerate there is an ocasionally a popping sound coming from the engine. About two months ago I was driving on the Hwy and all of a sudden the car would not go over 40 km/hr and was making a noise similar sound to a bad muffler but coming from the engine. I was advised by a friend to unhook the battery to reset the computer. I left it unhooked all night and the next morning the issue seemed to be resolved but still had poor acceleration. I took it to the dealer because I didn't want this to happen again. They said the only code they where getting was a bad outout speed sensor. After they fixed this the car had no issues except for the poor acceleration still. Today driving on the hwy I had the same issue. The car would not go above 40 and there was a loud deep sound coming out of the engine that I can only decribe as sounding like a bad muffler. I don't want to have to keep replacing the sensor every couple of months as this could be very expensive. Is there anything that could be causing the sensor to keep going bad like this? The mechanic at the dealer said that replacing the sensor should fix the loss of power problem but they would need to look further to find the problem with the poor acceleration. Which of course will cost more money.

First, I would expect the VSS they installed should still be under warranty. So contact them about that. As far as the lack of power, one of the most common problems is a plugged catylatic converter. When driving, if it plugs, it will cause a change in engine sound and also a reduction in power. I would have that checked.

Just for the heck of it, is the check engine light coming on? If it is, take it to a nationally recognized parts store and have them scan the computer for codes. Let me know what they are. If could just identify the VSS again, or there could be other codes and I need to know what they are.

Try that and let me know what you find. Also, most parts stores will do it for free, so there shouldn't be any additional money out of pocket for you.

Joe

Major hesitation from 0 MPH, then takes off like a rocket; checked compression, manifold vacuum, exhaust restrictions, installed a new TPS, and now we are trying to determine what the readings should be on the MAF sensor...should there be a 5 volt reference signal to it? This MAF is integrated with the IAT sensor (5 wire)