DIY Diagnosis: Causes of Low Engine Power

DIY Diagnosis: Causes of Low Engine Power
Dan Ferrell writes about do-it-yourself car alimony and repair. He has certifications in automation and see engineering. Low engine power normally means that your engine lacks baron during acceleration or that your engine suddenly fails to reach convention driving travel rapidly. While broken locomotive might could just mean that convention wear and tear has gradually taken away a lot of your cable car ‘s horsepower, this guidebook is concerned with abnormal power loss—a bankruptcy caused by a arrangement or part not working properly ascribable to a blame or lack of adequate maintenance. A low-engine-power condition can be caused by one or more of a long list of components in necessitate of care. fortunately, you can narrow down the number reasonably by knowing that some of the most common reasons for reduced engine ability have to do with the fuel, ignition, or discharge system.

Whether you are dealing with a faulty share or lack of proper alimony, the tests and strategies suggested below will help you regain your horsepower. The tests fall into different systems, specific faults, and conditions known to reduce engine world power. last, you are reminded of some authoritative diagnostics that may apply to your especial case. Each part or condition mentioned includes a “ What You Can Do ” section so that you can take some carry through when you think it ‘s necessity .

Systems That Can Cause Low Engine Power

We ‘ll go through the systems in ordain :

  1. Ignition System
  2. Fuel System
  3. Emission System
  4. Computer System
  5. Vacuum Leaks
  6. Transmission or Clutch
  7. Exhaust System
  8. Compression

But first I ‘m going to list some very simple checks you should do before you get started testing .

Four Checks You Should Start Out With

These are some authoritative but childlike checks to consider first .

  1. If you notice sluggish acceleration right after some work was done on your car, make sure that everything was connected back properly. Check for loose hoses, unplugged electrical connectors, and loose bolts, and if fluids were changed, look to see whether the right engine or transmission oil was used.
  2. Check your tires’ inflation pressure. If underinflated, your tires will drag on the road. Check inflation pressure with a tire pressure gauge when the tires are cold. Inflate tires 1 to 3 psi below the maximum pressure marked on the sidewall of your tires.
  3. Even if the check engine light (CEL) hasn’t come on, scan your computer. You may have a pending code that can guide you to the source of the problem. A malfunctioning sensor or actuator may cause the car computer (or transmission) to receive signals with the wrong voltage, causing the computer to lean the air-fuel mixture and rob your engine (or transmission) of power. Whatever codes you find, always test the circuit or components indicated in the trouble code. It is possible that a related fault may have the computer “think” that another circuit or component is failing. On some vehicle models, a failing camshaft position (CMP) sensor can cause your engine to suddenly lose power; the computer will most likely set a code if it detects a problem with this sensor.
  4. Many GM vehicle models come equipped with a Reduced Engine Power (REP) warning light, similar to the Check Engine Light (CEL). When this light (or both lights) comes on, you’ll notice the engine barely responding to the accelerator. This is a scary situation if the problem happens while you are driving down the highway or in heavy traffic. The most common triggers of this warning light are the harness connecting to the throttle position sensor (TPS), or the TPS itself. Other problems that can trigger the REP light come from the throttle body (including wiring), oxygen sensor, accelerator pedal position (APP) sensor (or harness), low engine oil pressure, or coolant loss. Watch the video below for more information about this problem.

Testing Eight Systems That Can Cause Low Engine Power

nowadays here are the eight systems that normally contribute to low baron, and how you can test them yourself .Worn out or fouled plugs will make your engine run sluggish. Worn out or fouled plugs will make your locomotive run dull. Photo courtesy of Zach Zupancic

1. Ignition System

sluggish engine demeanor can very often be traced to worn or faulty parts in the ignition system. respective components in the system need service at regular intervals. For exemplar, sparkle plugs and spark chew wires, but the ignition coil and ignition time should be checked as well. If any of these components cause you are not getting a good spark, your engine will be inert. What You Can Do: When you feel your engine inert, one of your inaugural checks should be to inspect the flicker ‘s force. Use an adjustable spark tester ( Thexton is an satisfactory trade name ) to check the spark ‘s health. Check at 40KV and 30KV. If your spark ca n’t bridge that gap at those settings, you may have worn out wires, a weak or failing allocator, a bad ignition coil or a bad ignition control module, depending on your particular faculty. Check the tests that follow, and consult your vehicle rectify manual for the proper diagnostic for your particular mannequin. If you do n’t have the manufacturer ‘s serve manual of arms, I powerfully recommend getting an aftermarket manual of arms for your exact model ( Haynes is a effective cheap stigmatize ). When doing a ocular inspection of the ignition system ‘s components, like the distributor cap, rotor, ignition coil, or coil pack, look for carbon traces, carbon buildup, and damage ampere well. Carbon traces are like small lines of carbon that form around these components. They can short out the electric potential going through the system, robbing the spark ballyhoo of the necessary electric potential to produce a effective flicker. Replace them if necessary. After checking the spark strength, if necessary check the following individual system components .

1. Spark Plugs

The trip plug may become foul with carbon deposits and other chemical byproducts, specially if the vehicle has n’t been maintained on the suggest agenda. Fouled plugs ca n’t produce an adequate trip to ignite the air-fuel mix. besides, after miles of service, the gap between the flicker park electrodes will widen due to wear. What You Can Do: Make a ocular inspection of the spark plug and check the gap between the electrodes using a wire antenna gauge and adjust it if necessity. Your car owner ‘s manual or haunt manual has the proper gap for your sparkle plugs. Your service manual can help you analyze your spark plug, which can reveal much about the circumstance of your engine .

2. Spark Plug Wires

precisely like flicker plugs, spark plug wires wear out, and after miles of mathematical process they can prevent the spark from reaching the spark hack. What You Can Do: Check each wire resistance using a digital multimeter ( DMM ) and compare your readings to the specifications in your repair manual. normally, you need about 5000 Ohms per metrical foot of wire. otherwise, replace them with a quality arrange of wires .

3. Ignition Coil

The ignition coil produces the high electric potential needed for the spark to jump the gap between the spark plug electrodes. That electric potential is typically anywhere between 4000 and 30,000 volts, depending on your particular vehicle model. ignition coils besides wear out or fail, resulting in a faint discharge, an intermittent flicker, or no trip at all. What You Can Do: You may be able to test the ignition handbuild ( randomness ) or coil pack in your fomite using a DMM, with the serve of your vehicle repair manual .

4. Ignition Timing

ignition timing refers to the relationship between the spark and piston position in the cylinder during the office stroke. The ignition time must be correct for the proper combustion of the air-fuel concoction. When ignition time is retarded you may notice an increase in fuel consumption, a drop in locomotive power, and poor acceleration. Timing problems can happen because of a worn out ( overstretched ) or damaged time knock or chain. even 2 or 3 degrees of dispute from the decline time can cause engine operation problems. On most modern vehicles ignition timing ca n’t be adjusted directly, but you still may be able to check timing yourself. On older models with a allocator, you can check and adjust the time yourself. For timing specifications, check the emissions control spine located in the engine compartment, or your repair manual of arms. What You Can Do: Check ignition timing using a time light and a tachometer. If your ignition arrangement uses a distributor, you can adjust the time yourself if necessity. Consult your fomite haunt manual. Your manual may besides have a overhaul schedule interval for the belt out or chain .

2. Fuel System

Although modern fuel injection systems may come in different configurations, they all share many components like fuel injectors, control condition modules, and sensors. Any of these components can fail and cause your engine to lose power. The fuel system can give you as much worry as the ignition system. When the engine feels sluggish, there are some parts you need to check .

1. Fuel Filter

Over time, the fuel filter becomes clogged, reducing fuel flow and preventing your locomotive from accelerating properly. What You Can Do: Check your car owner ‘s manual or repair manual for the service agenda for the fuel percolate. even if your filter is not the beginning cause of the problem, replacing the filter at the manufacturer ‘s suggested time interval will relieve stress from the fuel pump and increase its serve life .

2. Air Filter

Whenever your engine is running, the air filter in the breeze cleaning system traps crap, dust, and other alien particles and removes them from of the vent stream flowing into the engine. finally, the percolate clogs improving. And a badly clogged tune filter will make your engine exercise much harder. You ‘ll notice it. What You Can Do: Most car manufacturers recommend replacing the tune filter every 12 months. so form certain to check your vent filter, and replace it if necessary. Consult your car owner ‘s manual or repair manual .

3. Fuel Injectors

The most common trouble with fuel injectors leading to engine exponent loss is clogging. But they can fail vitamin a well. What You Can Do:

  • On throttle body injectors (TBI), you can check the injector’s fuel spray pattern by removing the lid off the air filter housing. The spray of fuel should be even and partially atomized, following an inverted V pattern. You can add fuel additive to clean a mildly clogged injector, or take it in to your shop for service. However, if the internal valve in the injector has failed, not just clogged, you’ll need to replace it.
  • On a multiport fuel injection system, dirty or clogged injectors are harder to detect. Depending on the configuration of your particular system, you may find it relatively easy to detach each of the injectors from their port to check their spraying pattern. On other systems, disassembly is a more involved process.

If you suspect dirty injectors, or you have n’t serviced the injection system in a while, you can try adding a fuel additive to the fuel tank. otherwise, you may have to take your car in for an injector symmetry test, which measures the total of fuel each injector sprays when energized .

4. Throttle Valve

Throttle plate malfunctions are not common but they do happen. What You Can Do: You can quickly check the strangle body to make certain the valve—the choke plate—opens in full when the accelerator pedal is in full depressed .

  • Remove the air ducts or air filter box lid to gain access to the throttle body.
  • Ask an assistant to fully depress the accelerator pedal with the engine off.
  • Verify the throttle valve responds accordingly to pedal operation.
  • Otherwise, adjust or fix the throttle linkage, or remove carbon buildup from the valve and throttle bore. Buildup may also interfere with proper valve operation.

5. Fuel Pressure Regulator

A defective fuel coerce regulator can allow either besides much fuel to flow into the engine or excessively little. What You Can Do: Test fuel imperativeness using a fuel pressure gauge. The test can point to problems with the fuel pump ( low blackmail or abject volume ), a clog fuel percolate, or a defective fuel coerce regulator. The accurate procedure may vary from one locomotive model to the following, but the general steps are the lapp :

  • Locate the Schrader valve on the fuel rail (this is a test fitting similar to the air valve on your tires). If your model doesn’t come with this valve, you still can connect the gauge directly to the fuel line using adapters (consult your repair manual).
  • Then, follow the steps described in your repair or service manual and compare your readings to the specifications.

A failing EGR valve can reduce engine power. A failing EGR valve can reduce engine power. Photo courtesy of Moosealope on Flickr

3. Emission System

Another possible, though not park, lawsuit for loss of engine power during acceleration is failure of the exhaust accelerator recirculation ( EGR ) valve. The EGR valve allows a careful sum of consume gases at higher-than-idle engine speeds to re-enter the locomotive to reduce engine high temperature and harmful emissions. When the EGR valve fails, it may stick open or closed. If the valve sticks ( or intermittently sticks ) open or fails to operate by rights, the most common symptoms you ‘ll notice are rocky idle and stalling during acceleration ; but other times you ‘ll just notice a lack of locomotive might when depressing the accelerator. What You Can Do: You can check the EGR valve at home, using a hand-held vacuum pump .

4. Computer System

As depart of the computer system, both the manifold absolute imperativeness ( MAP ) detector and multiply air flow ( MAF ) detector influence on the air-fuel concoction as controlled by the computer. normally, the car computer stores a worry code in memory when detecting a fault with either detector. What You Can Do: even if your Check Engine Light is not on, it ‘s a effective mind to scan the calculator for pending trouble codes. The most common problem with MAF sensors is a dirty smell component. You can clean it with electronic contact clean spray or MAF cleaner. Whether your cable car comes equipped with a MAP or MAF detector, you may be able to test it at home. Consult your vehicle repair manual .

5. Vacuum Leaks

Leaks may happen because of a informal, deteriorated, or break void hose ; a blow gasket, or a damaged restrict body gasket. What You Can Do: A common proficiency to locate vacuum leaks is to use a length of rubber eraser hose :

  • Start the engine and let it idle.
  • Using a length of rubber hose, put one end of the hose against your ear and use the other end to listen to the different vacuum hoses.
  • Trace the hoses with your diagnostic hose
  • Check around the edge of the intake manifold and throttle gaskets.

A leak void hose or gasket will produce a hiss fathom, and you ‘ll be able to hear it with your rubber hose. just be careful around moving engine components as you troubleshoot vacuum hoses .

6. Transmission or Clutch

If you have an automatic transmission, and you have n’t checked the transmittance fluid recently, it ‘s prison term to do it. If you have a manual transmittance, it is possible the seize is slipping. A park symptom of broken or contaminated automatic transmission fluid is slippage. Your engine races but your car does n’t move. Power is not being transferred to the wheels, giving the impression that your locomotive is lacking power. The same thing may happen in a manual infection vehicle when the clutch is worn out ; power does n’t get to the wheels .

What You Can Do (Automatic and Manual):

Automatic Transmission:

  • Check the transmission oil after the engine has reached operating temperature (drive or idle your vehicle for 20 minutes or more).
  • Turn off the engine and allow the engine to sit for three or five minutes.
  • Then pull the transmission oil dipstick.
  • Use a rag to wipe the tip of the dipstick clean of oil.
  • Fully replace the dipstick into its tube, and pull the dipstick out again.
  • Allow the dipstick to rest horizontally on the rag.
  • Oil level should be between the ADD and FULL marks toward the tip of the dipstick. Otherwise, add the necessary amount of the recommended fluid for your vehicle model.
  • Inspect the fluid. It should have a clear reddish color. If the color is opaque and brownish or black, or has a burnt smell, replace it. Consult your car owner’s manual or repair manual.

Manual Transmission:

  • Park in a safe spot, away from traffic and people
  • Set the emergency brake
  • Start the engine
  • Set the transmission to a high gear
  • Slowly, fully release the clutch pedal for two seconds (to avoid burning the clutch plate or flywheel) and reapply the clutch pedal
  • If the clutch is good, engine should stall or stop, as soon as you release the clutch
  • If the clutch is bad, your engine will keep running normally

Clutch slippage can be caused by a break clasp disk, leaking petroleum seal, binding seize linkage, clutch in indigence of alteration, or even a badly drive climb .A plugged or collapsed catalytic converter will reduce engine power. A plug or collapsed catalytic converter will reduce locomotive baron. Photo courtesy of The RedBurn on Wikimedia

7. Exhaust System

fair as your engine needs adequate air inflow, it besides needs proper tune outflow to push out all those gases produced during the burning action. hush, a morsel of back press is normal. The exhaust pipes, the catalytic converter, and the damper at the back of your car are all designed and sized with the goal of minimizing coerce. normally, water and acid are the most park enemies of a cable car exhaust system. But contaminant, system overheat, and high mileage can result in restrict air flow. The most park victim of exhaust system restriction is the catalytic converter. Besides failing or collapsing through convention tire, internal catalytic components can melt due to overheating and contamination. once the catalytic converter becomes plugged, you ‘ll notice a decrease in engine performance, and, depending on the character of failure, a impregnable smell of rotten eggs coming out through the tailpipe. But problems may not stop there. If the converter plugs up, it can overheat and burst into flames .

What You Can Do:

Test your run down system for high back imperativeness. The Temperature Test:

  • After driving your vehicle for about 15 minutes, park your car in the garage and turn off the engine.
  • Raise the vehicle and safely support it on jack stands.
  • Using a kitchen thermometer, take the temperature reading of the inlet pipe at the catalytic converter (be careful, temperature there can reach over 1400F [760C]).
  • Take the temperature reading of the outlet pipe at the catalytic converter.
  • A clear difference in temperature means a plugged converter.

The Rattle Test:
Depending on the type of converter you have installed and the failure type, if the catalyst elements inside the converter have disintegrated, the converter will rattle when reach with a arctic mallet. The Pressure Test:

  • Remove a pre-converter oxygen sensor.
  • Install a pressure gauge in the threaded hole.
  • Start the engine.
  • Take a pressure reading at idle and at higher speeds.
  • High pressure readings point to a plugged converter or muffler.
  • Disconnect the muffler and repeat the test to locate the obstruction.

The Vacuum Test:

  • Connect a vacuum gauge to the vacuum hose going to the power brake booster.
  • At idle, snap open and close the throttle valve allowing the engine to reach a speed of about 2500 rpm.
  • You should see the gauge needle drop to almost zero, return past your previous reading about 5in-Hg (inches of mercury), and go back to your previous reading. If the needle returns too slowly to the previous reading, you might have a restricted exhaust system.

Worn out cylinders or rings will decrease engine compression. Worn out cylinders or rings will decrease engine compaction. Photo courtesy of Wapcaplet on Wikimedia

8. Compression

Poor acceleration can besides have its source in locomotive compression problems. These problems are inevitable on high-mileage engines or those with a history of inadequate maintenance. And, as miles accumulate, more engine power is lost due to wear around cylinders, rings and pistons, and carbon buildup around valves. Rebuilding the locomotive might be necessary. What You Can Do: Do a compression quiz using a compression bore .

  • Remove all the spark plugs.
  • Block the throttle valve open.
  • Disable the ignition system and the fuel system (those with electronic fuel injection).
  • Connect the compression gauge to one of the spark plug holes.
  • And crank the engine for about six compression strokes.
  • Repeat the test on the rest of the cylinders.
  • Then, compare needle movement patterns and pressure reading to specifications.

Your vehicle rectify manual may guide you through this test .

Final Thoughts

You can avoid many low-engine-power problems, and many other issues, by following a proper regular maintenance agenda. The ignition and fuel system are often the elementary culprits behind the problem, but a numeral of components in other systems can besides cause the same topic. This template helps you find the reference of the problem, fix it, and save some money in the march. This article is accurate and true to the best of the generator ’ mho cognition. Content is for informational or entertainment purposes only and does not substitute for personal advocate or professional advice in occupation, fiscal, legal, or technical matters .

Questions & Answers

Question: What Is Fuel Combustion ? Answer: Basically, it is the ignition of the air-fuel mixture inside the combustion chamber when compressed by the piston. compression rises the concoction ‘s temperature and allows the sparkle to cause a violent explosion of the air-fuel. hera ‘s a more elaborate explanation of an internal burning engine ‘s four bicycle. hypertext transfer protocol : // … Question: I opened an injector fuel wrinkle because it leaks and put some magnetic tape on and connected it back. then I start it. It ‘s hard to start. What could be the problem with my cable car ‘s injector fuel note ? Answer: Fuel lines in inject models work under high pressure. Fixing a leak with tape wo n’t help to return adequate atmospheric pressure to the line. You ‘ll need to replace the line or the injector, depending on the mistake, to make the repair. It ‘s not safe operating an locomotive with a leaking fuel course. On some models, you can make the rectify yourself. Get a copy of the haunt manual for your finical mannequin. credibly your local car parts store has a copy, or you can buy one on-line. Question: Why my 2007 Chevy Tahoe REP sparkle came on ? Answer: Some coarse sources of trouble for this light come from a faulty accelerator military position detector or harness connection, depleted engine oil press, faulty accelerator pedal position detector, low engine coolant. If necessity, check with your local trader about electric potential technical service bulletin referring to this issue. Question: My Chevy Malibu keeps shutting off when starting and even while driving. The warn keeps saying office to engine reduced, locomotive disabled. What does this intend ? Answer: This is a safety feature programmed into the calculator to prevent damage. Make indisputable first base your battery is good. But there could be some engine ( like overheating ) or infection problem. Scan the computer for trouble codes and see what it says. Question: My ’05 Suburban a shows Check Engine and reduce exponent indication. It was temporarily resolved by replacing the accelerator cap and re-seating it. Where else should I look ? Answer: Reduced office is to protect the engine from wrong. Check the engine codes and see where they ECU detected the trouble and start there. There could be an engine or transmission trouble. Question: My Saturn ‘s engine lost baron while driving and died. now it wo n’t start. What can it be ? Answer: Check for fuel imperativeness. This could be a fuel system failure ( fail fuel pressure governor, regretful fuel pump, or a circuit problem ). Question: What is the argue for humble engine exponent ? Answer: Some models come equipped with a low-oil-safety feature of speech that will prevent your starting the engine to avoid major damage. hypertext transfer protocol : // … Question: I have a 2011 Chevy Impala LS. I recently got a reduce power to engine message. I ‘ve changed the camshaft detector and crankshaft. I besides checked my air filter trying to figure out what else could be the problem. I can drive it for about 5 miles and I will get the message. I turn the car off for about 5 minutes and start it back up and it ‘s all right. What else could the problem be ? I am getting something is clogged, timing swath, I fair do n’t know at this item. What could be the problem ? Answer: There can be several faults that may trigger the reduced power inner light. Check for disturb codes. The fault may come from a bad oxygen detector, bad fuel pump, choke position detector, defective or dirty MAF detector, badly converter, or throttle body. Question: My 2015 Chevy Traverse won ’ deoxythymidine monophosphate accelerate past 40 miles per hour and when the engine powered down a light came on. What is wrong with it ? Answer: Your car is probably operating in “ limp manner ”. This is to prevent damage to the engine. normally, a detector ( MAF ), problems with the transmission or catalytic converter trigger this manner. Make certain to download trouble codes from the computer and see where it points at. Question: The locomotive, though track, seems to lack power. What would I check ? Answer: Start with the fuel ( poor people fuel delivery ) and ignition ( poor spark ) systems. These are the most common sources. then follow the other systems listed in the post. Question: My 2005 Pontiac starts at subtraction 51, but the calculator indicates the engine has low power and it wo n’t run by itself. Everything else works, what could be the consequence ? Answer: The ECU might have gone into “ condom ” mode. normally, this indicates a good engine or transmittance problem. You need to take in the car for a diagnostic soon. Question: I have a 2000 Ford KA. When I ’ molarity driving the car, for example at 70 on the expressway, it will lose power and drop down to 40mph for no reason ( with my foot to the floor ), then a mile or 2 later it will go back to convention. It ’ s had new spark plugs, anoint, fuel trickle all within the last few months. What do you think could be the cause ? Answer: If the engine does n’t respond to the accelerator, for model, engine revolutions per minute remains the same, then there could be a problem with a detector. Download trouble codes, tied if the check engine light is not on. The computer memory could have stored a pending code that can guide you in the diagnostic. Question: My 2006 Chevy Malibu Reduce Engine Power light came on. It was very cold away. Will cold temperatures have something to do with a Chevy ‘s Reduce Engine Power light up ? Answer: normally, the trouble comes from a defective accelerator situation detector, fuel pump, oxygen detector, and other system. This other position may help : hypertext transfer protocol : // … Question: My reduced engine baron light is on, but I don ’ metric ton notification any abridge power at all, why would this be ? Answer: sometimes the computer will go into reduced engine power or limp-in mood without actually reducing office. however, you should check for trouble codes. normally, the trouble is with the Throttle operate system, but not all the time. You may want to check this other post : hypertext transfer protocol : // … Question: My 2009 Mercury Milan 4 cylinder has its check locomotive light on and blows smoke while on an incline. What is wrong ? Answer: First download the trouble codes from the car ‘s computer and see what they point to. sometimes, increased blow-by gases in the crankcase from the extra load ( uphill ) can cause roll of tobacco to come out the tailpipe if the PCV valve sticks open. Question: 2003 Vauxhall Corsa 1.4. When I drive the car is fine but when I have one or two passengers the cable car struggles to move as fast it moves actually slowly. And I was going up hill, I floored it and it wo n’t go about 20mph. And besides sometimes the cable car struggles a little to stay so I have to put my foot on the gas to get the cable car to start. What could be the trouble ? Answer: There could be more of a mechanical problem if this only happens when more than one person is in the car. Something is loose, possibly a detector connection. If this happens adenine well when there ‘s lone one person, check the fuel system pressure. Hope this help oneself. Question: My 2003 Oldsmobile Bravada Check Engine easy and Reduced Engine lights came on. It wo n’t go over 20mph. Is there a common problem with these cars ?

Answer: This other post may help : hypertext transfer protocol : // …

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