V6 running badly

  • Hi all
    Got a problem that is hard to explain.
    My 1995 mx3 will start ok first turn of the key but when i set off it will cough and splutter but it will start to pull once i get moving but when i get up to speed it is like it's fighting and when i go up a hill and put my foot down it's ok it's just when it's cruising it fight's.
    When parked and i rev it up to about 3000 or any steady rev it is like it's spluttering very eratic but it will go up hill no problem ????
    This started all of a sudden.
    I have checked all the small pipes changed the plug's even taken 1 plug lead of at a time and i could hear the miss on each 1.
    If i put it in limp mode i can drive it but a lot slower.
    Any help.

  • Hey,

    Pull codes as described in this link, it's easy and so useful :)

    Then post your results ;)

    Have you tried the accordian pipe between throttle body & VAF? They like to split. THere's so many possibilies, codes can help narrow down alot. Could be o2 sensors, dirty injectors, vacuum leak, dizzy… etc!

  • Hi again
    It keep's doing one long and two short so that is 12 TPS ?
    I did have a play with this over the weekend but it didn't seem to do anything but then i didn't know what i was doing but i moved it with the engine running should i have noticed anything when i moved it.
    also i have gone through all the pipe's.
    I have a V6 xedos what part's do you think i could swap to test but you will have to tell me what they look like as i don't know much.

  • Ahh that be your problem then.


    The ideal method for adjusting TPS-

    A rough method is to put the jumper between TEN->GND - Adjust the TPS so that the rad fan comes on when you start giving it gas (no fan at idle, slightest push of gas pedal - fan comes on).

    TPS is the black potentiometer on the right of the throttle body in this photo:

    Not sure if your xedos 9 TPS is interchangeable, should say part# on the silver sticker to the side. Hopefully just dirty contacts or the like. Otherwise grab one from scrap mx.

  • Thank's Marco
    It was the TPS swaped them over of the xedos 9 and away it went.
    The handy thing is i have a brand new TB in a box with a new one on it so that will go on it this morning.
    Thank's once again for your help.

  • Hi again
    I went out in it yesterday and it is still doing it but not as bad.
    If i unplug the TPS it will run better and it was a brandnew sensor that i put on and the part number is the same ???
    One more thing where is the fuel filter located i have a new one on order.

  • Hmm when you set the new TPS did you have it in diagnostic mode TEN GND shorted? Otherwise IIRC it won't set correctly/remember. If your TPS is properly set you should be able to unplug it during idle and have zero effect on idle.

    TPS setting is fiddly, you'd be best to do it with a multimeter and feeler guages.

    Fuel filter is pretty much under the battery tray on top of the tranny. Best thing to do it run the car, pullout connector under rear passenger seat until engine dies. This clears out lots of fuel in the lines.

  • Thank's for that infi i didn't have the jumper on when i set it so i will do it again and change the filter.
    Will let you know as soon as i have done it but it might be a day or so as i have a lot on today and maby the same tomorrow but first chance i get i will try again.

  • Hi again
    Changed fuel/air filter's reset the TPS still no joy.
    I will try to tell you the problem another way.
    If i hold the rev's at any speed 3500/4500 it is like the ignition is being switched of then on but onlt for a split second on off on off on all the time when you hold it at a steady rev.
    Don't know if that makes any sence to you.

  • Hmm a video might help alot. You could try posting this or searching for similar on mx-3.com. I'm out of obvious ideas :?

  • Will try a video but i am not sure how to post it ??
    Will do it a bit later on.

  • If you can get the video on your computer it's usually just a case of uploading it to a site like youtube or photobucket and linking to it

  • Hi Marco (or anybody looking)
    Does this make any sence to you.
    I have just moved the distributor a slight bit anti clockwise and the miss has gone i just have a fiat spot now when i touch the throttle but with the rev's up it fly's.

  • Yup that's how you adjust the timing! Check out the online manual section on mx-3.com -http://mx-3.com/manuals/showimg.php?file=/1995%20Workshop%20Manual/B2/B2-008.gif

    You can use a timing gun with TEN and GND shorted in the diagnostics box to set timing. The ecu will automatically fine tune it if it's working properly. I'm surprised it was that far out that the ecu couldnt fix it! Glad the missfires gone at least :)

  • Hi again
    I have set it best i can but got no timing light .
    But where ever i put it i still have the flat spot when i put my foot down even when setting off it will cough and splutter but spot on with high rev's.
    It seam's i can't win with this car.
    if i blip the throttle it will pop back and splutter then take off.
    ps. do you think the belt could have jumped a tooth.

  • It may be worth checking your mixture setting.
    On the wife's Golf we turned it down for MOT emissions and forgot to turn back up. We had misfires and popping on throttle pick up (acceleration) but once it got up to speed it was OK.

  • Hi
    I don't know if there is a way to set the mixture on the mx-3.

  • Mixture Tuning :shock: Carbs.

    Its all Controlled via ECU now and AFM.

  • Hi all
    Is it posible for the timing belt to jump on one cam say just one tooth and couse this sort of problem.

  • @3949969a4a=Alan:

    Hi all
    Is it posible for the timing belt to jump on one cam say just one tooth and couse this sort of problem.

    Yeah could cause the problems you described.

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