K8DE hesitating (mostly when cold)

  • My K8DE seems to hesitate when inbetween completely cold and full temp.

    when properly cold it seems OK. When warmed up fully it is OK but feels a little weak below 4k - not as much torque as when cold… (over 4k = :P )

    Checked both VRIS valves in neutral today and they flick open and closed very quickly when the engine is revved.

    All vac pipes seem OK, and if I pull the vac pipe out of the front rocker cover, the idle speed drops noticeably.... so I think the vac side is OK.

    Any thoughts? it is all bog std. I have done about 180 miles with 'catalean' fuel system treatment and it runs and sounds great, water temp position is solid. just the hesitation when warming up....

    Any advice / tips appreciated :D

  • hmmm o2 sensor if u have one..c wat lambda is..

    check intake for air leaks

    maf sensor aswell

  • iceman (trev) i have had this problem since i have owned my car and i still havent cured it 6 months later. djmarcopolo on here has cured his and it ended up being the inlet manifold gasket leaking. generally its the air filter piping will have a split in it somewhere so have a good pull around and see if you can find a split, other than that check oil levels as that can play a part in the hesitation too (5w30 for these engines, i use semi synth, some use fully synth). hope this helped

  • Thanks Dan and Jay. :)

    Its only a slight hesitation really. condition of allhoses looks suprisingly good.

    The rocker covers are both leaking and it looks as if they may have been taken off recently to try to (bodge) fix it. this would require removal of the inlet manifold.

    I'll check there.. when I fix the rocker cover gaket leaks I'll put on a new inlet manifold gasket and red hylomar.

    Also the cone in the MAF does not move smoothly… by hand it feels a bit stiff... maybe I'll have a good look at that first.?

  • it could well be the VAF. mine cone is super light to move by hand. like yours though, once warm its absolutely fine so i dont know if that would be the metal expanding creating a "better fit" for the gasket. thats what is going on in my mind anyway..

  • The fact that the rocker covers are leaking wont help it at all.

    Remove the VAF sensor piper and crack open the throttle butterfly. If the inner face is gammed up with crap. Get some brake cleaner and give it a bloody good spray.

    Mine had a similar problem. And after cleaning the throttle body and VAF helps a lot.

  • i wouldnt recommend cleaning the VAF, they are extremely delicate and attempting to clean it could make things worse rather than better, especially if its not at fault. inside the throttle body is best sprayed out with carb cleaner. spray hard into the holes inside. I used about half a tin cleaning mine out.

  • I sorted my hesitation out by removing throttle body and inlet manifold and reseating with new gaskets and gasket sealer, guess they let a little air in down the sides :D

  • Well I've been driving it properly and it seems to have mostly cleared itself. I will still check out all of the above. Good responses thanks ;)

  • Had a better look this weekend. The throttle body was quite gummy - I cleaned it up, checked the MAF = fine, re fitted the cone filter (took std airbox back off) and checked for leaks. When I drove it, once warmed up it started cutting out and hesitating badly. Quick look under the bonnet and I had forgotten to tighten the jubilee clip on the throttle body :oops: - there was an audiblle hiss even at idle. Once tightened the car was running perfectly. nice and responsive at all revs.

    The only other issue is a bit of a jerky response on / off the throttle, mainly in 1st & 2nd. I think this is due to a bit of play in the engine mounts. (another job to add to the list!)


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