Repair Topics / Acceleration

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Car Acceleration Questions and Answers

This category contains featured questions as examples. They relate to most vehicles.

Question: 1995 Mazda rx7 Turbo 13B mileage: 79,000. I am having a problem with my acceleration. If I only put the throttle down a little bit before half way, the car runs fine. It will boost and accelerate all the way to 7000 if I wanted it to. But if I push the throttle past half way, it stutters, and feels sluggish, if I floor it the check engine light comes on. It is intermittent though, because sometimes it will go when floored and sometimes it won't. I've put new secondary injectors, oxygen sensor, and bac valve. What could be the problem, the TPS? Or the boost sensor?

Answer: Check the fuel filter, fuel pump and fuel pressure regulator to make sure they are all functioning properly. Also, check the catalytic converter to make sure they are not plugged.

Question: 1998 Ford Taurus mileage: 70,000. Hello, I was wondering if I could get your opinion on a problem I am having with my car. First the stats. Problem: when ever you accelerate the car especially between 25-35 mph, the car acts likes its out of gas, doesn't die but as you push the accelerator it doesn't respond right away then grabs. As long as you have the accelerator pushed, it runs perfect. When you let off and then push again it kinda bogs then catches. I though maybe a clogged or bad fuel filter, replaced it. Bad fuel pump, replaced that. Still does it. not as bad but its still there. My next guess is bad fuel injectors. I am in the process of borrowing a fuel pressure gauge, but what will this help if one or two injectors are bad? I don't know what other components could be bad. I thought it was the torque converter but on startup and engage in drive it connects perfectly. I am pretty confident that it is the fuel. Rotor, cap, wires are all new (in replacement of what I thought might be a spark problem). Other than taking it to a shop and hooking it up to a machine, which will run some bucks, is there any other diagnostics I can do to narrow it down. Any information would be a great help. UPDATE: replaced: fuel pump, MAPP, Throttle Position Sensor only things left are module on dist. and ECM.... out of ideas.

Answer: Your described symptoms they can be your electric fuel pump or fuel filter. These parts are high replacement items. To be sure of failure you will have to monitor a fuel pressure gauge while in operation. Make sure the fuel pressure, under load stays within specifications. If not the fuel pump is bad and needs replacement.

Question: 1999 Pontiac Grand Am 2.3 quad 4 mileage: 88,000.  My Grand Am has the 2.3 liter quad 4 engine and an automatic transmission.   When trying to accelerate quickly from a stop it shakes or seems to misfire.  If I let off the gas for a second it will recover and then accelerate normally.  It experiences no trouble when accelerating from a higher speed, only from a stop, and only if done so quickly.  Also, no codes are shown in the computer.

Answer: Your car is ready for a major tune-up including spark plugs, coil housing, fuel filter and air filter.  Also, perform a fuel pump pressure test just to be safe.

Question: 1985 Olds Delta 88 307 mileage: 129,000.  My car has had problems accelerating. It seems to be doing fine when I am around town but when I get to the interstate, that is when it does not go and seems like it is missing or something.  I thought I needed a tune-up so I got it done and the problem still continues.  Somebody mentioned to me that it might be my fuel filter.  I just got my fuel pump replaced also.  Please help me.  Thank you so much for your time.

Answer:   Check the catalytic converter to make sure it is not “plugged” or restricted.  Also, check the fuel pump pressure.

Answer: If the car is only going 10 mph in second gear and the engine rpm is close to redline, the clutch is slipping do to excusive wear. Check to replace as needed.

Question: 1994 Pontiac Transport 3800 mileage: 100,000.  When you press the accelerator slightly, it hesitates, likes spits and sputters, or when doing 40 mph, when you keep your foot on the pedal slightly, it will shake and hesitate.  Does not matter whether it is hot or cold.  If you are in traffic, stop, and go, sometimes causes it to stall.  (When you accelerate then take your foot off the gas quickly).  Any ideas?  Changed fuel filter, plugs, air filter, oil and transmission filter.  Nothing changed.  Your help would be greatly appreciated, I would hate to take it to a dealer and be overcharged without having an idea of what it could be.

Answer:   Your car is equipped with a computer controlled engine management system.  An independent auto service center can scan your computer for fault or error codes.  The information should pinpoint the mal functioning components.

Question: 1995 Dodge Caravan 2.5L mileage: 59,000.  Under light acceleration, when warm, with or without A/C, the engine seems to starve for fuel.  The power just goes away.  The engine never stalls.  If gas pedal is depressed the power returns and away I go.  The local Dodge dealer says the EGR is faulty.  This engine has no "Classic" EGR that I can find, or that is listed in the repair manual.  Over the past several months the following items have been checked or replaced: Fuel pressure, idle position sensor, plugs, rotor, cap, wires, fuel filter, air filter.  No error codes are generated in the on-board computer.

Answer:   Check the fuel pressure regulator.  It may be at fault

Question: 1990 Mazda MX-6 4 cy.2.2L mileage: 135,000.  When trying to accelerate from a stop, the engine will lurch and shake violently.   It is the worst when letting the clutch out into 1st gear, moderate into 2nd gear, and above that it runs fine.  The lurching isn't quite as bad if you accelerate slowly, but if you try to take off fast, it almost stalls out the engine.  Help!

Answer:   Replacing the clutch assembly and motor mounts should fix the problem.

Question: 1993 Chevy Truck 6 cyl 4.3 lit   mileage: 90,000.  My truck has started to miss on acceleration.  I replaced the usual suspects, plugs, wires, rotor and dist. cap, fuel and air filter, PCV valve.  This didn’t have any effect, so I took it to the Chevy dealership for a diagnostic. Their conclusion was that I had carbon buildup and for 165.00 they would decarb my engine.  I knew that what they would do was run some chemicals through it, so I said no thanks, bought a carbon removal product, added it to my gas and nothing.  It still hesitates upon acceleration.  Maybe my catalytic converter is partially plugged.  How would I check it?

Answer:  Try replacing the oxygen sensor.  A weak signal from the sensor may be causing your problem.  To test for a plugged converter, drill a small hole in the exhaust pipe right before the catalytic converter.  Install a temporary hose fitting and attach a long rubber hose and a 0 to 10 pound pressure gauge.  With the gauge inside the car, drive up a hill or accelerate and read the pressure.  Normal is 2 to 3 pounds, restricted 4 pounds or higher.  The drawback to this method is the small hole will need to be welded shut after the test; a minor job if you have a welder.

Question: 1985 Mazda RX 7 mileage: 125,000. My daughter's RX7 - Rotary engine- has lost acceleration. Its like it is starving for fuel. Although, we can give it gas and the idle goes up. We do that to keep it from stalling. Although its bad enough that she can't drive it, except around town. What do you think this is?

Answer: Perform a compression check to determine the condition of the engine. Check to see that the exhaust is not plugged or restricted, especially the catalytic converter. Check the fuel pump pressure also the decceleration system in the intake manifold.

Question: 1992: Dodge Shadow 4 cylinder mileage: 84,000. Hi...my question is about my aunts car actually. She has had the car for almost 5 years with no problems...NOW in the last year it has started doing this weird thing quite frequently and every time she takes it someplace it never duplicates the problem, so everyone thinks she is nuts. I didn’t believe her either until it happened to me several times when I was driving it. This is what it does.... you will be driving along...usually on the highway when all of the sudden your speed will start dropping from say 65 all the way down to say 20 mph. If you push on the accelerator, it doesn’t do a thing it just sounds like you are revving up the engine. It will last that way for quite awhile, and usually you have to pull over because of the speed decrease. Then all the sudden it will be okay again. Like I said, she has taken it several places and even had it hooked up to various computers, but the car will never do it when a mechanic is looking at it. Can you think of SOMETHING that they may be able to check? The car is an automatic, by the way. Thanks

Answer: Is the car low on transmission fluid? If no, your aunt’s car may be ready for a transmission service. Replacing the transmission filter and fluid may fix the problem. After the transmission service, if the problem persists, a transmission overhaul may be next.

Question: 1986 Ford Tempo 2.3 mileage: 68,000. When you apply pressure to the accelerator there is a hesitation, then jerks and then accelerates. I have replaced the spark plugs, plug wires, distributor cap, rotor button and fuel filter. Any ideas?

Answer: If the oxygen sensor has not been recently replaced, a new one should be installed. Also, perform a fuel pump pressure test. Clean fuel injection system including throttle bore, idle speed control motor and passages. If the problem still exists, scan the computer for trouble codes.

Question: 1984 Saab 900 turbo 2000, mileage: 160k. I have owned the Saab for 18 months now and recently, over the last 2 months I have lost acceleration at low revs. I have recently serviced the vehicle to manufacturers specification including rotor arm, distributor cap, air filter, oil filter, oil (10-40 fully synthetic), spark plugs and silicone high tension leads. The timing was set to 20 degrees at 2000 revs but the fuel mixture was not touched. When I first bought the vehicle, it accelerated well from any revs and speed but has now dropped off. Incidentally, I have tested the compression and all four cylinders have 190 lbs. I hope I have given you enough information to make a diagnosis and perhaps a remedy.

Answer: First, check for boost from the turbo. We cannot remember if your car is equipped with a "boost" gauge on the dash. If not, a temporary will work. While driving the car under acceleration, you should have approximately 5 lbs of boost. If no boost is present, you have turbo problems. Other things to check or replace are fuel filter, oxygen sensor, coolant temperature sensor, or air flow meter.

Question: 1990 Honda Accord Ex   mileage: 120,000.  My car has some difficulty in accelerating when I stop at a traffic light and then proceed. It will not go beyond 20 mph, and the engine has a loud noise.   After 30 seconds later, the problem disappears.  The problem occurs occasionally, especially in the local road.  In addition, I was told that I need a valve adjustment very badly when I did the oil change this January.  Does the problem have anything to do with it? My transmission is leaking.  Do you know how much it would be to fix it?

Answer:   May be caused by the transmission; something as simple as being low on fluid. Worse case scenario is after 120,000 your transmission may need to be overhauled.  Not able to give an estimate on the fix without knowing where the leak is coming from.

Question: 2000 Chevy S-10  mileage: 50,000.  I have a Chevy S-10 with very low mileage.  It has no AC.  It is in excellent over all condition.  Recently I began to have acceleration problems.  It runs great when cold and sometimes even when heats up.  But most of the time, once it warms up, it pops and sputters on acceleration.  I can't figure it out.  Fuel pump weak after warm-up!  Fuel regulator valve!  Electrical!  I hope you can help.

Answer: Your car is ready for a major tune-up including spark plugs, plug wires, fuel filter and air filter.  Also, perform a fuel pump pressure test just to be safe.