[16v] low end torque (or the lack thereof)

[jason@scirocco.org (Jason)]

At 03:32 PM 8/13/2002, T. Reed wrote:
>Not really. I have noticed that setting my dpr current to 5 mA instead of
>10 mA increased power around 4-5k a little bit but took more away from the
>low end. I think it's unlikely that this is a fuel problem, though. My
>exhaust barely even smells :) and I rarely get smoke from the tailpipe
>except during startup and even then it is minimal. My oxygen sensor
>voltage is reading around stoich (.7 volts, no?). But.. I've been wrong
>before.

I agree that it doesn't sound like a fuel problem.  If it wasn't getting 
enough gas, you'd get pinging, and if it was getting too much, you'd get 
dark black smoke.


>It takes just under 2 seconds to rev it to 2k from idle in neutral. Most
>of that is just waiting for the engine to respond to the change in
>throttle position. It hesistates at idle and then begins responding after
>a second or so. Really annoying..

Have you checked for vacuum leaks?  (including in thr injector seals?)


>The power loss is definitely noticible above idle as well, but less so.
>It's not bad at all when I'm just going at a cruising speed.

k.


>I will pull off the timing belt cover and double check my cam timing
>-again- today. I've already had my timing belt slip a couple teeth before,
>so anything is possible but I'm pretty sure it'll still be dead on.

It would definitely be worth it, just to rule that out.
What is high-RPM power like?
...and when did this start -- when you put the Euro cam in, or just all of 
a sudden at some other point?


>What I was saying in my other post today was that maybe my timing advance
>is not functioning at all. And that's why I need to advance it all the
>way to get decent performance.

That's a possibility.  On the other hand, timing advance is needed as your 
engine gets higher in revs.  You need more timing advance then to ensure 
complete combustion... because the motor is turning so fast, you actually 
want to ignite the air/fuel mixture early because it takes time for the 
whole mixture to ignite...  The faster the motor is turning, the less time 
you actually have for the mixture to explode -- so the earlier you have to 
time the spark.

At low revs, pretty much independent of load, you don't need that much 
advance.  So in theory, having no advance at all would hurt high revs more 
than low revs.  Check it of course, but I'd lay my bets elsewhere.

When you say that the motor hesitates at idle when responding to a change 
in throttle position, explain that -- does it sputter, hiccup, and act 
miserable and then *boom* it spools up, or does it just not budge off idle 
while sounding "normal"?

>Hmm.. more stuff to look in to.

Does it hesitate in response to throttle changes over 2k as well?
Have you done a compression check?

Jason





>-Toby
>
> >
> > >I have to turn the A/C off at every stop. If I don't, 0-10 mph takes 6 or
> > >7 seconds (not an exaggeration -- the people behind me start riding my ass
> > >when the light has been green for that long and I'm barely rolling). The
> > >only alternative is to rev to 2 grand (still about 1.5 seconds) and drop
> > >clutch, which sometimes chirps the tires (lightly releasing the clutch
> > >just makes the rpms dip back down to idle and then rise slowly.)
> > >
> > >The car runs great/fine above 1500 rpm..
> > >
> > >Is this normal? It can't be.. for the longest time I've been assuming the
> > >16v engine just blows off-idle but now I'm think I have serious
> > >engine issues (but is it fuel or ignition? or mechanical?).
> > >
> > >Where should I start looking?
> > >
> > >Ignition timing is set to full advance (setting it at 6 degs just makes it
> > >worse)
> > >DPR current is set to 10 mA fluctuating +/- 1 mA
> > >Idle stabilizer is working
> > >Plugs, plug wires, bosch cap, rotor, hall sender all new
> > >O2 sensor within last year and a half
> > >Fuel filter changed
> > >Euro intake cam
> > >Crank<->Cam and Cam<->Cam timing dead on at last check
> > >Idle air bypass screw set mostly by experimentation because no adjustment
> > >   could yield a proper dwell meter reading
> > >Idle and full throttle switches test out okay
> > >3" sewer pipe running to stock opening in lower airbox
> > >k&n air filter, possibly with some crankcase breather oil soakage on it
> > >All vacuum hoses replaced
> > >Intake boot leak next to throttle body patched
> > >No exhaust leaks - new downpipe and new dynomax superturbo muffler
> > >
> > >
> > >Any ideas? Even without the A/C the car is slow off the line..
> > >
> > >I would appreciate any input!
> > >
> > >Thanks,
> > >
> > >-Toby
> > >