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

[treed2@u.washington.edu (T. Reed)]

> >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?)

Yes, I've looked everywhere. Replaced all the vacuum hoses, sealed the
crack in my intake boot, and replaced injector seals, o-rings and bakelite
shrouds.

Is the dipstick tube a leak point for CIS-E cars or just digifant? Mine
appears to be in good shape but who knows? Maybe it's bad and leaking
air in to the crankcase..

> >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?

It has kinda been this way since I bought the car.. but my memory is fuzzy
there. The euro cam didn't change the power below 4500 at all. But now the
car pulls to redline without that 'overrunning" sound it used to have. The
torque peak is still about 4500 but above that it keeps making power
rather than petering out like it used to.

I triple checked the cam to cam and cam to crank timing when I installed
the euro cam and it was right going in and right going out. I checked cam
to crank timing again a week after installing it and it was dead on.

> >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.

Okay, well now with John Erickson saying that bypassing the knock box
causes retarded ignition timing I think I have a pretty good theory for
what's wrong, maybe even moreso if I can get some confirmation. The thing
is -- I tried my knock box in my brother's 88 GTI 16v and it ran the same
as it did with his knock box (However, we didn't drive it around, just
revved it in the parking lot). That led me at the time to believe that my
knock box was fine and it was just the fuel pump relay output that was
bad. Time to try that again and drive it this time I guess.

I didn't try his box in my car because he was afraid if faulty wiring in
my car was what killed my knockbox, it might kill his too. We both figured
that it was a safer test to put my box in his car because it would be
pretty hard for the computer to destroy his sensors.. etc.

> 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"?

If I let it idle for a minute with no foot on the gas, then mash the gas,
it usually drops about 50-100 rpm then returns to idle and stays there for
1 to 1.5 seconds, then begins creeping up to 1100 then 1200 then it ramps
up faster and faster and begins revving at 'normal' speed above 1500 rpm.

> Does it hesitate in response to throttle changes over 2k as well?

No.. or only slightly. Above 3k I have great throttle response.

> Have you done a compression check?

No, I have like 3 compression testers but none of them will work with my
engine - I have the kind that threads in but its not long enough to reach
down the spark plug hole, and I have the kind that you push and hold in
place but it is too small of a diameter to make a seal around the hole..
and I have another one that won't work either.

Maybe someone in Seattle has one that I could borrow or use at the next
tech day or northwest show?

> Jason

Thanks!

-Toby