hesitates..

Hello everyone !

i'm here for the first time and this is an amazing forum!

i own Subaru LEGACY 2007 2.0 165 hp and i'm a fan of Subaru for many years,

i have a problem I could not find a solution for, and i thought maybe to consult you here, hoping to find a solution , There is a strange problem in my car .. -

when i press the accelerator pedal the vehicle hesitates for a few seconds

maybe for 3-5 seconds and barely starts moving in those seconds.

and then after the little delay he bursts forward with great force (as it should )

guys, i spent a lot of money on the diagnoses, and nothing!

the problem remained, the only progress i could get was that i discovered that

when i disconnected the battery and it reset my computer, the problem disappeared for a week to 10 days.

other things to note - that while the problem occurs (hesitation) until the seconds are over and the vehicle starts to travel normally, on the right side of the passenger compartment there is like buzzing ound, like a bass that shakes the window as well, and that for a few seconds.

so What do you guys think?

has anyone experienced a similar problem? or maybe an idea and direction to continue? many thanks guys, if i missed details i would be happy to add and add information

Given that the engine is a 2.0 with 165hp I'd consider that it's not having any turbo, so any intercooler issues can be ruled out.

Start with cleaning MAF and throttle body.

Also check that all hoses are on tight and no leak exists. You may need to do a so called smoke test to verify this.

If the problem persists then check and possibly replace the MAP sensor. The hesitation issue is often but not always an indication that the MAP sensor isn't behaving correctly.

The sound you hear might be a heat shield that's loose.

While you are at it also clean the ignition coils, replace spark plugs - and remember to keep track of the old plugs and if they don't have the same color on electrode/insulator then you may have a problem with a single cylinder. If applicable clean or replace ignition wires too since it's high voltages that can take strange paths if things aren't correct.

ehsnils,thank you very much for your answer and your time.

I've done most of the things you've mentioned before.

except for smoke test, and I did everything at the car dealer in a central garage with original parts only.

I even changed the fuel pump and timing belt just in case..

the MAP & MAF sensors were cleaned, tested and found to be normal.

Also tested and cleaned throttle body

I also did extra treatment with 44K additives and also cleaned a catalytic converter

and there is no change .. I do not know whether this is relevant, but at high-speed drive, sometimes there is a smell of fuel vapor, not strong ... but a little bit.

I really do not know what to do.

I will do the smoke test you mentioned, if they did not do it as part of all the adventures in all the garages I have been to this day.

thank you for your help,

When the normal actions don't give anything then it's time to do a data log. In reality that's one of the first things to do in order to narrow down where to look for issues and avoid throwing unnecessary parts on the car.

But it's never too late to do a data log, and there's a lot of people here that can help you interpret them.

Thank you all,

in the meantime I found another clue .. I can drive without the cap of the fuel tank - (30min +)

and it does not turn on any light checking engine at the dashbord,

and it goes towards the EVAP system in my opinion

( is it possible that vacuum leak may occur through the EVAP system?)

maybe the fuel tank pressure sensor is bad ??

I'll keep you updated, anyway -

thank you all.

It could be the purge valve that's problematic too, but it's a bit strange behavior for that.

I think that a data log would be very useful at this stage.

Did you get a "sucking" sound when you opened the tank cap? It should be an underpressure in the tank if everything is normal after you have driven a bit.