3k flat spot and more

[tjs98jetta]

I often notice a very slight momentary hesitation in my car when accelerating medium-slowly through about 3K rpm. I assume this is the infamous 3K hesitation. It's really a very small effect, and when pushing harder (throttle more than 1/2 way or so) it's hard to notice because there's so much more going on. I've assumed it's happening because the ECU is changing mode in some way as the rpm builds, but this is just a supposition on my part.

In any case, the car goes far faster when you never get below 3K anyway, so what's the problem :-)

[dodge1979]

Ive done some upgrading on my s4, but am running the stAndard but new turbo. My injectors are the upgraded ones from five-o recomended by Lucas. Now im experiencing the same surging effect you describe. Im thinking personally its down to fuel pressure. So ill be fitting an updated pump and pressure regulator to see if this sorts it. Either the originals ate worn or they would not be man enough fir the fuel demand anyhow. Im a little weary of chip upgrades, themost I personally would like to do is to sort out the silly aircon on off stumble. I would in the future like to experimentation a different turbo, but dont see the point yet still the fueling issorted and ive experimented with getting more air into the engine with simple mods like porting

Or a similar route as Dave has taken with his se. Have youdone any work with the chargecooler? This is a very good ate too cover and fairly simple really with good results.

Darren

[Rich H]

What you describe sounds like 'lean surge' it's when you are at constant mid throttle and you get a gentle surge then it drops off and repeats.

My old Porker did it when I buggered up the fuel map. It means you are running slightly lean at part throttle but could be OK elsewhere.

(Or it may be unrelated of course!)

[dodge1979]

Yes, thats just wat it feels like,although the reason im thinking fueling issues is because also upon acceleration it can do it too. So my theory was either fuel or a boost leak. im gonna try fuel first, because at the end ofthe day the pump and pressure reg are 15years old and it does no harm to ensure theyre new and well up to the task! Dealing with waste gates is a little more involved, with setting them up correctly etc.