Announcement

Collapse
No announcement yet.

Hesitating at full throttle ?

Collapse
X
  • Filter
  • Time
  • Show
Clear All
new posts

  • Hesitating at full throttle ?

    Hello guys

    I just bought a 2003 60kw roadster but I have an issue with it. When warm, the engine stops accelerating at full throttle. I can hear slight misfiring from the exhaust when this happens. If I release the throttle then it can rev up again. I changed map and air temp sensors and o2 sensors (this one was faulty). Turbocharger needed rebuild so I replaced the CHRA. Wastegate is ok. Boost is stable (rock solid 1 bar). I'm sure it's not going to safe mode. There is no error code from ECU.

    I wonder what I could check now. I wonder if a faulty fuel system (pump or injectors) could not be the culprit. Spark plugs are new. I changed the fuel pressure regulator as well.
    Using Torque I noticed that STFT is increasing to about 10-20% when accelerating. from my opinion it looks like the engine is missing fuel and the ECU tries to compensate with trim. But maybe this is a normal ECU behaviour I don't know. Is it possible that the fuel pump flow decreases when warm ?

    Thanks for sharing.
    Jerome

  • #2
    Hi & welcome.
    Could it be blocked fuel filter that is restricting the fuel flow? https://www.evilution.co.uk/index.ph...vicing&mod=977
    Just a guess.

    Comment


    • #3
      Hi Mr T,

      fuel filter was changed few thousands miles ago. Moreover problem happens after driving about 10-20 miles.

      Comment


      • #4
        Check your rear reluctor rings.
        Also, get yourself logged onto www.theroadster.net where you will find there are a lot more roadster owners than there are on here.

        Comment


        • #5
          Hi, the reluctor rings look good and I can get the misfire effect when parked as well. If I open full throttle when parked, engine hits max rpm then slow down to about 4000 rpm with misfires. It looks like something is missing after 1-2 seconds. Maybe fuel ?

          Comment


          • #6
            As a general rule, misfires under load are ignition related, general misfires are fuel related.

            Check your tank venting system in case of blockage creating vacuum in fuel tank.

            Comment


            • #7
              Yes that an idea I had. Increasing vacuum would make the pump working harder and harder. I will have a drive with the fuel cap removed.

              Comment


              • #8
                Originally posted by marcjero View Post
                Yes that an idea I had. Increasing vacuum would make the pump working harder and harder. I will have a drive with the fuel cap removed.

                To be honest I don't know how to check that now that tank venting is so complicated with purging kit. Maybe removing the cap will work. Or, when it plays up again, pull over and remove the cap and listen for any inrush of air?
                If not that, I'd suspect an electrical/electronic component fading with heat.
                Given you can induce the misfire at standstill, might be worth doing it at night with the engine cover off and looking for stray sparks from the coils to the plugs.

                Comment


                • #9
                  Removing the cap didn't solve the problem.

                  Comment


                  • #10
                    I wonder if it isn't a crank position sensor on the way out - but the usual symptom from them is complete engine cut out when warm when the engine has to idle (though I've heard the earliest detectable sign is occasional misfire while driving). and easy re-start once cooled.

                    Comment


                    • #11
                      Yes maybe. The point is that engine startup is no problem warm or cold. Moreover reving under light load is not problem also. And I don't see the link between load (boost) and the crank position sensor.
                      Last edited by marcjero; 10-08-17, 02:57 PM.

                      Comment


                      • #12
                        Originally posted by marcjero View Post
                        . And I don't see the link between load (boost) and the crank position sensor.
                        Right enough, no real link. CPS is really only telling the ECU where the crank is at - for both ignition and fuelling purposes - and is pretty digital. Missing under load is usually ignition components failing (typically weak insulation on the HT side) because it is harder to introduce the spark to a cylinder holding high pressure.

                        Easy cold starting implies there is sufficient fuel flow - at least to begin with. You'll just have to whittle down the list of possible suspects though if the CPS is suspect I'd leave it to worsen a bit and confirm the diagnosis before diving in to change it. They can be a right PITA to remove.

                        Comment


                        • #13
                          Thanks so the next test will be to look for sparks at night

                          Comment


                          • Thrumbleux
                            Thrumbleux commented
                            Editing a comment
                            Give that a shot just to eliminate it as a possibility. If the plug leads have been removed without the correct tool (or badly with the correct tool!) they could be damaged. Coil packs have been known to fail also. Getting to them is a bit cramped as they're hidden under the inlet manifold.

                            Might be worth pulling the plugs for a reading to see if there's any clues there.

                        • #14
                          BTW, when mine burned exhaust valves and was misfiring (completely non firing) on cyl # 1, the EML lit up. Not suggesting you have anything as serious, but a prominent misfire will invoke the EML.

                          Comment


                          • #15
                            No EML on. No ECU error code so far.

                            Comment

                            Ad Widget

                            Collapse
                            Working...
                            X