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Thread: Lost acceleration again

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    Unhappy Lost acceleration again

    A few days ago my gear box died .. it died without any bang or clunks ... it died slowly and eventually the car stopped moving .infact I was on my way to work and the car just stared to slow down and would not move . still have not figured out what happened to that one

    About a month ago I replaced my gearbox (same part number ) and transfer case with a spare one put in new mitsu atf ... the car came back to life and was as good as new .. was doing 0-100 in around 6.5 seconds ..

    This morning when I drove it felt like I was driving my previous gearbox it seems to be slipping & slow . The push that you get (30-60kph) when pulling the car hard was missing.

    Where should I start..

    Just for the sake of asking let say I have fried my gearbox again .. do I only need to replace the clutch (friction plates) ? .. where can I get those

    Yesterday I accidentally pushed the car from D to N thinking it was in tiptronic mode .. the rpm rushed pretty badly for a second .. but I don’t think this event was the culprit for the car slowing down

    I cant seem to find any "slow acceleration" threads here, most threads just have broken gearboxes. I really like the car but the last 2 months have been YUK.


    Really loved that Pulls for a month and now it’s gone ...
    Last edited by iftekhar.frt; 14-04-2019 at 06:43 AM.

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    Anyone ?

    Could a small .. really small boost leak cause this ?

  3. #3
    TAR's Avatar

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    from your previous posts it appears that you drive your car with your foot flat to the floor at all times.

    Does it drive normally and change gear as expected when you are not ragging it about?

    I can't work out of you think you have a performance issue or a broken gearbox.
    '97 Manual Legnum in silver with some subtle mods

    My first VR4 - '97 Legnum Dark Green & mean ...it was love at first sight - now sold

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    Quote Originally Posted by iftekhar.frt View Post
    A few days ago my gear box died .. it died without any bang or clunks ... it died slowly and eventually the car stopped moving .infact I was on my way to work and the car just stared to slow down and would not move . still have not figured out what happened to that one

    About a month ago I replaced my gearbox (same part number ) and transfer case with a spare one put in new mitsu atf ... the car came back to life and was as good as new .. was doing 0-100 in around 6.5 seconds ..

    This morning when I drove it felt like I was driving my previous gearbox it seems to be slipping & slow . The push that you get (30-60kph) when pulling the car hard was missing.

    Where should I start..

    Just for the sake of asking let say I have fried my gearbox again .. do I only need to replace the clutch (friction plates) ? .. where can I get those

    Yesterday I accidentally pushed the car from D to N thinking it was in tiptronic mode .. the rpm rushed pretty badly for a second .. but I don’t think this event was the culprit for the car slowing down

    I cant seem to find any "slow acceleration" threads here, most threads just have broken gearboxes. I really like the car but the last 2 months have been YUK.


    Really loved that Pulls for a month and now it’s gone ...
    were you the gut that did not use amsoil ATF in the auto box?


    if you have a boost gauge fitted and you should, and it is plumbed correctly into the plenum chamber and it reads the expected boost pressure when you flaw it, then a small boost leak prior to the plenum chamber will not make any difference. a small boost/vacuum leak is only really an issue at low rpm low boost or vacuum conditions. once you are producing lots of boost then a little bit escaping will make no difference the boost control will just keep ramping it up to maintain the set boost pressure. The only thing that might happen is the MAF will report air flow X and the engine sees air flow X - a little bit, so the engine will get slightly more fuel than it needs. but if you have an AFR gauge fitted and you should, you can see if you run into any over fueling problems.

    what boost pressure are you running is it mental high or just normal raised pressure to about 1 to 1.2bar.

    I have never actually heard of anyone killing the clutches in a auto box that has been using amsoil ATF regularly. i have trashed gear sets with chipped teeth but not bad clutches but i use amsoil ATF and i launch my auto box every once in a while when i get to the front of the taffic light queue.

    launching = brake hard on, auto box in D raise rev to 2500rpm and left foot off the brake right foot on the accel to the floor and go.
    this does not do your gear box any good but it is fun.
    if you want to do this you better have good ATF in the autobox. and it does not come much better than amsoil ATF.
    there is no reliably fast way to get you VR4 off the line, it is very consistent and will beat a standard manual clutch off the line every time.
    if the manual has a trick heavy duty clutch/twin pate then they could use a full drop the clutch appoch, 6000rpm and a sideways slide off the clutch peddle and it might hook and give them a good launch but they will not be able to get it to hook like that 5 time in a row.

    back to my rambling ways. lol
    Last edited by Davezj; 17-04-2019 at 12:30 AM.

    Bye for Now!

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    one more thought for you.
    did you disconnect the battery when you swapped the auto box. i presume so as you swapped the TCU with the auto box.

    you have to give the autp box about 30-100 miles of driving for the fuzzy logic in the TCU to relearn the shift points and the shift force required to make efficient gear changes.
    if you have just fitted the auto box and ragged on it straight away then the re learning of the TCU is probably messed up.
    so disconnect the battery again and drive normally no launches until the silky smooth shift points are achieved and then you can rag it off the line.

    itis a possibility.

  6. #6

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    Quote Originally Posted by TAR View Post
    from your previous posts it appears that you drive your car with your foot flat to the floor at all times.

    Does it drive normally and change gear as expected when you are not ragging it about?

    I can't work out of you think you have a performance issue or a broken gearbox.
    yup I drive with a pretty heavy foot ..
    yes it does drive normally .. the gear changes are as expected .. even the torque convertor lockups 4 and 5 are almost unnoticable on this chnaged gearbox

    neither can i workout btw performance and gearbox

    since the last 2 months have been all around gearbox so my mind just keeps thinking on those lines. what pushes me towards performance issues is that it has just happened suddenly .. if it was atf or gear i would expect it to give me some hints before getting to this stage

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    Quote Originally Posted by Davezj View Post
    were you the gut that did not use amsoil ATF in the auto box?


    if you have a boost gauge fitted and you should, and it is plumbed correctly into the plenum chamber and it reads the expected boost pressure when you flaw it, then a small boost leak prior to the plenum chamber will not make any difference. a small boost/vacuum leak is only really an issue at low rpm low boost or vacuum conditions. once you are producing lots of boost then a little bit escaping will make no difference the boost control will just keep ramping it up to maintain the set boost pressure. The only thing that might happen is the MAF will report air flow X and the engine sees air flow X - a little bit, so the engine will get slightly more fuel than it needs. but if you have an AFR gauge fitted and you should, you can see if you run into any over fueling problems.

    what boost pressure are you running is it mental high or just normal raised pressure to about 1 to 1.2bar.

    I have never actually heard of anyone killing the clutches in a auto box that has been using amsoil ATF regularly. i have trashed gear sets with chipped teeth but not bad clutches but i use amsoil ATF and i launch my auto box every once in a while when i get to the front of the taffic light queue.

    launching = brake hard on, auto box in D raise rev to 2500rpm and left foot off the brake right foot on the accel to the floor and go.
    this does not do your gear box any good but it is fun.
    if you want to do this you better have good ATF in the autobox. and it does not come much better than amsoil ATF.
    there is no reliably fast way to get you VR4 off the line, it is very consistent and will beat a standard manual clutch off the line every time.
    if the manual has a trick heavy duty clutch/twin pate then they could use a full drop the clutch appoch, 6000rpm and a sideways slide off the clutch peddle and it might hook and give them a good launch but they will not be able to get it to hook like that 5 time in a row.

    back to my rambling ways. lol
    no ams oil here (i am not from Australia).. i used the Mitsubishi sp3 .. but again if it was the atf how could this happen over night :/
    even when i think the car is running up to proper standards .. my car has no mods except for boost guage .. i have never seen it running above 10psi (0.7 bar) (which i think is stock settings)... so no crazy boost
    i have never like never launched this car is that way ..
    (I dont rev in D )for me launch = auto mode or tip mode ... D .. lift of the brake and just floor it .. i have managed 6 seconds (0-100) launches in this way which is more that enough for me
    this is a video i recorded about 3 days ago which i thought was optimal .. https://drive.google.com/open?id=1c9...zizlhFeJ1nNhFy
    Last edited by iftekhar.frt; 17-04-2019 at 03:55 AM.

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    Quote Originally Posted by Davezj View Post
    one more thought for you.
    did you disconnect the battery when you swapped the auto box. i presume so as you swapped the TCU with the auto box.

    you have to give the autp box about 30-100 miles of driving for the fuzzy logic in the TCU to relearn the shift points and the shift force required to make efficient gear changes.
    if you have just fitted the auto box and ragged on it straight away then the re learning of the TCU is probably messed up.
    so disconnect the battery again and drive normally no launches until the silky smooth shift points are achieved and then you can rag it off the line.

    itis a possibility.
    yes i did a TCU and ECU reset since then have driven around 400kms after that ..
    it was driving fine the day before yesterday .. yesterday morning i noticed this problem
    the only event i would say which was not normal is as I mentioned the first post that I accidentally pushed the car from D to N thinking it was in tip mode and then panicking i put it back into D
    Last edited by iftekhar.frt; 17-04-2019 at 03:54 AM.

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    Some also suggested that may be a waste gate is stuck .. have you guys heard of this problem .. do both the turbos have a waste gate?

    UPDATE : I can hear a hissing noise when under load .. the gauge shows more than 6-7 psi at that time
    Last edited by iftekhar.frt; 17-04-2019 at 04:33 PM.

  10. #10
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    There is a waste gate on both turbos
    But both are fed from the same pipe coming from the plastic elbow on the front end of the throttle body.
    By the sound of it you are not running much power at all on 0.7 bar. At that pressure the turbos will be able to maintain that from about 1500- 2000 rpm all the way up to the rev limiter and should be very stable. No drop at all.
    But if you can hear a hiss there must be a farly major leak.
    Do a boost leak test and find it.

  11. #11
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    Check your transfer box oil. Bad or low oil in there gives a very slushy acceleration, like the gearbox is slipping excessively.
    And definitely find a way of doing a boost leak check!

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    regarding the boost leak check I can do that only after both turbo output pipes join right ? i.e. when looking from the front on the front left onwards

    the area that can be checked are .. left wire pipe -> inter cooler -> throttle body elbow - > check on both open and close throttle.

    the output pipe from both the turbo can not be checked correct ?

    or can i just do some thing like think link right after the maf .. https://www.youtube.com/watch?v=atretf9u-Mc&t=203s

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    So I did a boost leak test today. From the maf onwards

    Apparently there were 3 leaks

    1) when some one replaced the original BoV and installed the VTA BOV he did not plug-in one side of the hole .. it is now closed to with a 1 inch plastic cap
    2) intercooler input
    3) throttle body elbow

    The car seem to be now holding the pressure no hissing sounds

    But now there is another problem the car feel like it’s suffocating .. giving blue smoke and not going above 5psi

    The idle revs don’t go above 5200 rpm
    Last edited by iftekhar.frt; 20-04-2019 at 05:46 PM.

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    Did you repeat the leak test? That sounds like you have an even bigger leak.

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    Quote Originally Posted by Nick Mann View Post
    Did you repeat the leak test? That sounds like you have an even bigger leak.
    yes i did in the end . it was holding pressure now

    it has something to do with plug-ing that BOV hole.. when I remove the plastic cap it runs fine
    Last edited by iftekhar.frt; 21-04-2019 at 12:01 PM.

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    Since the Revelations keep coming and I bought this as a used car

    my car does not have an O2 sensor straight piped 3inch.. no cats

    according to a well known mechanic here when an O2 sensor is not plugged in the ecu over fuels to prevent knock... because my car is already over fueling and since now all the leaks have been fixed when the maf records excessive airflow (> 5200 rpm) the fuel has already been maxed and car suffer the suffocating problem .. the purposely left opening (by the previous owner) near the BOV solves this problem because the maf does not get to record this air flow

    does the above make sense to you guys ?

    Another thought is that since i did not reset the ecu after the leak fixes i had a badly trained ecu which could not keep up with the sudden change and i should plugin that hole reset the ecu and then try again..

    any good guide on how i can log parameter from the ecu?

  17. #17
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    when you did the boost leak test from the MAF did you remove the crank case ventilation hose from the inlet pipework from the y Pipe section after the maf and before the turbos that goes to the rear rocker cover.
    if you don't remove this pipe when you do the boost leak test you are pressurizing the crank case and potentially can blow the oil seals out on the crank and cam shaft, PCV valve as these are the place for the pressure to go if you are lucky the dipstick will pop up out of the tube and release the pressure, you are pressurizing from both side of the piston rings when you leave this pipe in place.

    as for the ECU learning to over fuel due to the leaks, just disconnect the battery and then reconnect and the engine and gearbox will relearn the levels the engine needs to know.
    Last edited by Davezj; 22-04-2019 at 02:17 PM.

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    Quote Originally Posted by Davezj View Post
    when you did the boost leak test from the MAF did you remove the crank case ventilation hose from the inlet pipework from the y Pipe section after the maf and before the turbos.
    if you dont remove this pipe when you do the boost leak test you are pressurizing the crank case and potentially can blow the oil seals out on the crank and cam shaft as this is the only place for the pressure to go as you are pressurizing from both side of the piston ring.

    as for the ECU learning to over fuel due to the leaks, just disconnect the battery and then reconnect and the engine and gearbox will relearn the levels the engine needs to know.
    No i did not unplug any hoses .. is that some thing to worry about now ? ..... are you saying this because of the blue smoke because that seems to be gone since opening that BOV hole...

    so if my O2 sensor is missing can it play a part in this problem

    then again refereeing to the original post .. every thing was fine a few days back ... how can all of this suddenly come into play

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    if you are not dripping oil on the flaw then the oil seals are probably OK.

    the ecu has fuel trims and it can add or remove fuel as needed by the air going into the engine. but that need the O2 sensor to tell the ECU if the engine is running rich or lean and then the ecu will add or remove fuel. but if you dont have an O2 sensor then the ecu will be using a default set of fuel table that will run the engine rich and safe until you get it fixed.
    so if the car was running ok like this with a massive air leak then the 2 issue could have cancelled each other out.
    When you fixed the massive air leaks you have made the engine run supper rich and this will make dark smoke out of the exhaust and you should small un burnt fuel out of the exhaust.
    once you replace the O2 sensor it should fix the over fueling issues as the ecu will be able to use the fuel trims to adjust it correctly. but a battery disconnect will help reset all the issues to zero before the new O2 sensors does it work and sets up the fuel trims correctly.
    you can check the O2 sensor and the fuel trims via Evoscan.


    if you can avoid it you should never need to run a VR4 without an O2 sensor to make it run rich, that is a very bad idea.
    if you need more fuel you can turn the fuel pressure up with a fuel pressure regulator or remap the fuel tables to give more fuel.
    Last edited by Davezj; 22-04-2019 at 11:42 PM.

  20. #20
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    No O2 sensor at all? Not even the standard one? Stock narrowband?

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