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Thread: acceleration problem...

  1. #1
    Join Date
    Nov 2004
    Posts
    205

    Default acceleration problem...

    what could cause these symptoms...

    acceleration becomes terrible after a few minutes of driving...
    it seems that there is a lag in something causing it...
    it sometimes takes 2 to 3 seconds for power to pick up...

    when i step on the gas... even if it is on neutral, the power
    picks up late... as if there is a limiter

    fuel filter and fuel pump is new...

  2. #2
    Join Date
    Nov 2004
    Posts
    205

    Default

    anyone?

  3. #3
    Join Date
    Jan 2006
    Location
    New Mexico
    Posts
    192

    Default

    Quote Originally Posted by pong View Post
    anyone?
    Pong, Have you done a good close look at ALL your vacuum lines/hoses? I would start there. When was the last time you changed your spark plugs, distributor cap and rotor? I would start with the hoses, check the fittings as well, see if they are snug. Maybe you don't have a vacuum leak at low RPM, but as the pressure builds so will the vacuum leak.......
    M20 525/7 Bore: 84.50mm Stroke 81mm CR 8.5:1, blue printed/dyno & custom chip. Boost @ 6.5psi ~246hp @ 5300rpm / torque @ 269ftlbs. @ 4250rpm

  4. #4
    Join Date
    Nov 2004
    Posts
    205

    Default

    actually... the problem only pops up when i initially step on the gas... after that brief period... everything is normal again... it can rev up to 4k rpm without any problems... any gear... as long as i get over that tiny hiccup...

    was wondering... why is this the case when i drive after a few minutes and not right after i turn on the engine (even if engine is already hot, stop and turn off engine for
    around 5 mins... everything is ok... until after a few minutes again)

    had terrible vacuum leaks before... changed a bunch of hoses and the rough idling was gone... spark plugs were changed too... any other ideas?

    distributor and rotor... i think ill check that... but the last time i went to my mechanic...
    he said it was ok... no problems with it...

  5. #5
    Join Date
    Nov 2006
    Location
    Germany
    Posts
    475

    Default

    WOT acceleration will test the fuel delivery and spark systems maximum capabilities so if foot on the floor acceleration is normal, then it may be safe to reason that these basic systems work as they should.

    If the off-idle (throttle tip-in) is garbage only after the engine is hot, then I would lean towards a sensor (02 or engine temp) not performing properly.

    You say you solved all of your vacuum leaks. Your symptoms can be caused by unmetered air entering the engine. How is the connection between the throttle body and air/mass meter or MAF (I don't know which one you have)? I remember somebody around here finding a rather large hole in the bottom of their boot between the throttle and meter...but the unmetered air usually makes the cold start/running less than stellar.

    You could also have bad cat converters that go south when hot. This condition would make the engine down on power at WOT...I have seen an Audi muffler full of dry dog food cause some serious power and driveability issues.

    Brian

  6. #6
    Join Date
    Sep 2007
    Location
    Michigan
    Posts
    335

    Default

    What is the condition of the throttle cable and the cruise control cable where they go through the brackets and to the engine? I had a similar situation on a 325 because the zip tie that was holding the cable to the bracket was loose and there was odd slop in the cable. When you stopped for a while it relieved the tension and would hiccup as it was settling into a proper groove when you got going. Odd situation but an easy fix.

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