My father called today to tell me that when he steps on the gas in his 99 Subaru Impreza (at normal operating temperature), the car moves dangerously slow. Does anyone else have experience with this issue and how to fix it? He was a master mechanic in the old days but never learned how to repair cars in the electronic age.

Thanks for your help.

  • 1
    Is this a turbo engine? Commented Feb 26, 2014 at 11:05
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    Also, what transmission? Is this a sudden problem? Did the car work fine and then cease accelerating? Or has it become worse and worse?
    – Bob Cross
    Commented Feb 26, 2014 at 19:27
  • Don't have all your answers. All he told me is that it is a 2.2L engine and is an automatic. I believe the problem occurred all of a sudden and was not a gradual thing. I do not live near my dad so i have not seen the car lately.
    – user4578
    Commented Feb 27, 2014 at 2:28

4 Answers 4


Poor acceleration is sometimes caused by dirty spark plugs or clogged air filters. Keep in mind that the spark plugs are probably more difficult to reach on a 99 Subaru than most other cars since the Subaru has a boxer engine. But, if you feel up to it, you could try replacing the spark plugs ( and/or air filter if necessary ) and see if that helps the issue.

There are very few clues to go off of here though, poor acceleration could be caused by many different things. With only one symptom it's hard to diagnose the problem with any accuracy, and as costly as it can be, the solution here might be to take it to Subaru mechanic.

Hesitation or low power at slow acceleration


I'm an ASE Master certified tech, and have been doing this for 25 years. The likely cause is not the coil or plugs or the air cleaner but the fuel filter. It is probably blocked so the engine can't get the fuel it needs to run correctly.

It is a common problem with Subarus. I would change the filter and go from there.

  • 1
    I haven't seen a completely blocked fuel filter on a Subaru but I have seen poor performing ones - what would you have to put in your fuel tank to block a fuel filter completely? (and the fuel covers do lock on close). An old one results in somewhat reduced acceleration at higher rpm, behaviour at low rpm should be fine. Replacement is every 50,000km (30,000 miles) for SOHC and every 100,000km (60,000 miles) for DOHC.
    – timbo
    Commented Sep 18, 2015 at 1:35

Coil pack failures are very common

Also check to see if the snorkel after the mass air sensor could has a crack or rip in it. Introducing of air after the sensor will create the no power condition. And lastly if its turbocharged the turbo might have locked up and perished.


my personal experience. The fuel filter in the engine bay was clogged and had very dirty fuel. The car was sluggish inspite of new plugs and spark cables. The throttle body was also cleaned and voila! the change was instant!

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