Hesitation around 5K RPM - '04 2.0
Results 1 to 10 of 10

This is a discussion on Hesitation around 5K RPM - '04 2.0 within the General Maintenance, Troubleshooting & Accidents. forums, part of the Tech & Modifying & General Repairs category; Hoping maybe someone else has had this issue as well. In the last week, I have been seeing a lot ...

  1. #1
    Registered User
    Join Date
    Nov 2007
    Posts
    3

    Question Hesitation around 5K RPM - '04 2.0

    Hoping maybe someone else has had this issue as well.

    In the last week, I have been seeing a lot of hesitation in my engine. The car is just barely over 60K miles. I checked the fluids and all is fine. However, when under hard acceleration, it is uneven from 2500-4500 RPM.

    Between 4500 to 5000 RPM I really feel hesitation. Once past 5000, though, I rocket up into the red.

    At first I was thinking fuel pump, as it felt as sluggish and uneven as an HO 5.0 Capri I had back in the day, but why would it suddenly scream past 5000?

    Is this a turbo issue? Possibly the blow off valve?

    Any thoughts?

    Thanks

  2. Remove Advertisements
    ClubWRX.net
    Advertisements
     

  3. #2
    He simply abides. SD_GR's Avatar
    Join Date
    Jul 2002
    Location
    CA, US
    Posts
    22,474
    I Support ClubWRX
    Clean your MAF.
    WRX Info Links, Courtesy TheJ
    The world breaks everyone and afterward many are strong in the broken places. Ernest Hemingway
    I lied. I cheated. I bribed men to cover the crimes of other men. I am an accessory to murder. But the most damning thing of all... I think I can live with it. And if I had to do it all over again - I would. Benjamin Sisko
    DISCLAIMER: Opinions expressed are the author's alone and are inherently worthless.

  4. #3
    Registered User
    Join Date
    Nov 2007
    Posts
    3
    Quote Originally Posted by SD_GR View Post
    Clean your MAF.
    I apologize, I am not familiar with the acronym. What should I clean?

    thanks

  5. #4
    Registered User JSarv's Avatar
    Join Date
    May 2007
    Location
    Illinois
    Posts
    330
    Clean your mass air flow sensor = MAF. It is located near your air cleaner box. Removed the two screws that hold it in undo your wiring to the sensor and remove it. I personally used NON-Chloride brake cleaner and sprayed the sensor (of course the side that comes out of the intake hose). Electrical contact cleaner would actually be 100% the best for this. But brake cleaner is fine AS LONG AS ITS NON-Chloride. Autozone even though they are idiots, have exactly that, its in a green can, can't think of the name, but that is what i used.

    Also do you have a boost gauge? Are you getting a CEL? I just sold a EG Civic that needed an o2 sensor and it had a hesitation between 1800-2400 rpms with no CEL. As soon as the CEL came on there was no hesitation just HORRIBLE fuel mileage. Have you noticed a decrease in fuel mileage? It is a rare possiblity you have an o2 sensor (Probably your upstream) that is on its way out, but is not bad enough that the computer is picking up on it. It actually happens alot more than people think.

    Clean your MAF and if that doesn't help, I would reset your ECU. Check boost. And consider replacing the upstream o2 sensor.

  6. #5
    Registered User 68sprintb's Avatar
    Join Date
    Dec 2005
    Location
    San Jose, CA
    Posts
    434
    my '05 does has a similar issue, i figured it was cause of the factory tune having a hiccup... wouldn't an AP or UTEC smooth that out?
    Blobeye Syndicate #75
    2005 OBP WRX Sport Wagon
    Stewart Warner Boost & Oil temp gauges / OEM 20 mm rear bar
    Cobb stg 2 / STi uppipe / Crucial Racing downpipe
    Stromung 2.5" catless centerpipe / Scooby Sport New Age centre pipe & backbox

  7. #6
    Registered User JSarv's Avatar
    Join Date
    May 2007
    Location
    Illinois
    Posts
    330
    Quote Originally Posted by 68sprintb View Post
    my '05 does has a similar issue, i figured it was cause of the factory tune having a hiccup... wouldn't an AP or UTEC smooth that out?
    Could, given it was a fuel or timing issue with the stock map. I would consider routine maintenance prior to spending $695+ on a piggy back to fix a hesitation problem. Not saying its not the factory mapping, just saying with the mileage, it could be a sensor or vacuum problem.

  8. #7
    Registered User
    Join Date
    Nov 2007
    Location
    uk
    Posts
    2
    Quote Originally Posted by mixjuan View Post
    Hoping maybe someone else has had this issue as well.

    In the last week, I have been seeing a lot of hesitation in my engine. The car is just barely over 60K miles. I checked the fluids and all is fine. However, when under hard acceleration, it is uneven from 2500-4500 RPM.

    Between 4500 to 5000 RPM I really feel hesitation. Once past 5000, though, I rocket up into the red.

    At first I was thinking fuel pump, as it felt as sluggish and uneven as an HO 5.0 Capri I had back in the day, but why would it suddenly scream past 5000?

    Is this a turbo issue? Possibly the blow off valve?

    Any thoughts?

    Thanks
    change plugs that will stop it dead ,my wrx was same and i changed everything on it plugs last and it gone?

  9. #8
    Registered User
    Join Date
    Jul 2008
    Posts
    2

    Check Engine Light - P0171, hesitation at 4k RPM

    I had the same problem with sputtering at 4k rpm but I also had a check engine light.

    The Subaru manual might take you down some dead ends with this fault code and if I had known then what I know now I would have cleaned the MAF first. It takes about 10 minutes vs hours to follow all the trouble shooting steps in the manual...in fact the manual doesn't even mention the MAF until the very end of the trouble shooting steps.

    Here's a little back ground:

    CEL came on at about 104k miles. Bought an OBD reader and got a P0171 - System Too Lean code, (the Subaru manual calls it a Fuel Trim Malfunction (A/F Too Lean)).

    (Be smarter than me and go to your local auto parts store. Most will read the code for you for free vs. buying your own OBD reader which will set you back about $75 - $200 depending on which model you buy. I opted for a mid priced one and it didn't add any value at all in this whole ordeal so might as well buy the most inexpensive one that supports Freeze Frames if you just have to have one.)

    Followed the trouble shooting steps in the manual:

    1)Check exhaust system for leaks, none found.

    2) Check intake system for leaks. Found a somewhat loose hose clamp on the turbo to intercooler connection, but aside from that nothing. Cleared the code and drove it around and the CEL came back on so the loose hose clamp wasn't the problem.

    3) Check fuel pressure: 43 psi with pressure regulator disconnected and 35 psi with regulator connected, all good as per the manual.

    4) Changed the fuel filter anyhow since I'm at 104k miles. Drove around and the CEL came back so the fuel filter wasn't the problem.

    5) Check the engine coolant sensor....actually didn't check it but the freeze frame file stored for the P0171 showed the temp was 190F when the fault occured so I figured all was OK.

    6) Check pressure sensor...actually couldn't do this since the OBD reader I bought doesn't have the ability to directly read sensor outputs.

    I was about to either give up and take it into the shop or drop $150 on a new MAF when I ran across this thread.

    Pulled the the MAF and the temp prob, (the amber colored bulb), was coated with dirt and the other two small sensor wires down inside the MAF were also dirty. Took some CRC Brake cleaner, (the green stuff with toluene), as mentioned below and gave all the sensors a good blast.

    Reinstalled the MAF and took it for a spin and it was like driving a new car.

  10. #9
    Resident meany-rator 06wrx4me's Avatar
    Join Date
    Jun 2006
    Location
    Nor Cal
    Posts
    11,420
    I Support ClubWRX
    helluva first post, welcome... to bad thread is a year old.
    2014 Ford Fiesta ST

    06 WRX, HAWKEYE # 001 <T-boned and sold>

    COILOVER TABLE
    TURBO TABLE

  11. #10
    Registered User
    Join Date
    Jul 2008
    Posts
    2
    thanks. This is my first post ever anywhere and maybe went over board with the details.

    I searched for this fault code several times before but nothing useful was ever found. Not until I typed in subaru hesitation did I hit paydirt.

    Cheers

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •