Sign up ×
Motor Vehicle Maintenance & Repair Stack Exchange is a question and answer site for mechanics and DIY enthusiast owners of cars, trucks, and motorcycles. It's 100% free, no registration required.

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.

share|improve this question
Is this a turbo engine? – Paulster2 Feb 26 '14 at 11:05
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 Feb 26 '14 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 Feb 27 '14 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

share|improve this answer
+1 spark plugs! – AM_Hawk Jan 21 at 22:45

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

share|improve this answer

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.

share|improve this answer
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 Sep 18 at 1:35

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!

share|improve this answer

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.