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Spark Plugs - pre ignition issue
Check your fuel mixture & a/f! CIS_E has a nasty
habbit of going lean even on stockish 2.0's. How is
the a/f? & check to make sure the ks does work.
--- Jason <jason@scirocco.org> wrote:
> Ben's pinging is quite a bit more than that... It
> will ping not only under
> throttle transitions (which can tend to happen on
> moving-part air meter
> systems), but also under constant load. Whether the
> KS is actually working
> in his case is really unimportant in terms of
> finding the problem with
> detonation... Obviously it would potentially
> correct it, but as they say,
> that's putting a Band-Aid over a bullet wound. The
> question here is, more
> than anything else, why the car is pinging like
> this.
>
> Ben, some questions:
>
> 1. How is it on cool evenings and mornings? If it
> still does it,
> something changed, because it didn't do it this
> spring when it was cool out.
> 2. Have you done a compression check to see what
> your effective
> compression really is? (Mine puts 195-205psi, and
> can take only about 9'
> before I start hearing pinging on 93).
> 3. Perhaps the Schrick 260/276 cams are resulting
> in hotter exhaust
> manifold temperatures, which is resulting in the
> pinging... and causing you
> to not be able to advance to stock timing.
> 4. Since the advance on the 16V is vacuum-actuated,
> perhaps the additional
> air you're flowing is causing more of an advance at
> higher loads than would
> normally be the case. Check your total advance with
> and without the vacuum
> line connected and compare it to that of a stock 16V
> at 2000, 3000, and
> 4000rpm. (I'll do mine if you need me to).
> 5. IIRC, isn't it the KS Box that controls RPM and
> Load-Dependent ignition
> advance? Since we already know that something is
> kooky with your KS Brain
> (i.e. it doesn't do shit), perhaps you should swap
> it out with another and
> see what happens.
> 6. Since it's so difficult to get a true reading of
> ignition advance at
> idle with your cams, who's to say that just
> averaging the timing mark is
> actually where the timing is set to? It could be
> that your timing is, in
> fact, advanced further than the reading shows, but
> the KS Brain is
> interpreting the lumpy idle as knocking, and
> continually messing with
> timing? Disconnect the KS brain and see if the
> timing is less jumpy at
> idle. If not, measure timing at 1500rpm (or as low
> as you can get a smooth
> idle) and use that to interpolate base 1000rpm
> timing compared with another
> 16V.
> 7. Another possible crutch would be to use a
> ridiculously low temperature
> thermostat. Your car runs fantastically cool oil
> temperatures, but IIRC
> you'll see "normal" (i.e. needle on the LED) water
> temps. Reduce the water
> temp and you'll cool the head some more.
> 8. Did any of the plugs you remove indicate that
> perhaps only one cylinder
> was experiencing the detonation? Check it out -- if
> so, it might be a
> partially-clogged injector that is causing one
> cylinder to lean out.
> 9. Where is your O2 sensor? Stock location, right?
> 10. Could it be that the wiring in your A/F gauge
> is causing an O2 sensor
> reading that is too high, resulting in your Fuel box
> leaning out the
> mixture more than it should? The gauge shows you
> running just lean of
> stoich, but hey, you never know...
> 11. Do you have a pyrometer (or whatever those
> non-contact high-temp
> thermometers are called)? If so, check the temp of
> each runner on the
> exhaust manifold and see if one is running much
> hotter than the
> others. That would indicate a potential source for
> the problem...
> 12. It does also ping under full-throttle, right?
> If so, we can ignore
> the O2-sensor arguments. ;)
>
> Jason
>
>
>
>
>
>
>
>
>
>
> At 06:32 AM 7/24/2003, Allyn wrote:
> >after the 2.0 swap (standard compression) on the
> rieger, i can hear some
> >onset to detonation during shifts (as i accelerate
> into the next gear). this
> >is with standard timing, and only happens on really
> hot days. the only
> >electrical part i changed during the swap was the
> knock sensor that came
> >with the 2.0 block. my guess is that all it takes
> is a bad knock sensor.
> >i'll know soon enough, once i dig up the old sensor
> and throw it back on.
> >Al
> >
> >----- Original Message -----
> >From: "Benjamin Harder" <vwtype53@yahoo.com>
> >To: <scirocco-l@scirocco.org>
> >Sent: Wednesday, July 23, 2003 11:36 PM
> >Subject: Spark Plugs - pre ignition issue
> >
> >
> > > I've been having an issue lately with
> pre-ignition (pinging) on my mk1's
> > > 2.0 16v engine. Engine is freshly rebuilt with
> approximately 11:1
> >compression,
> > > running CIS-E, stock ignition, always on 93
> octane, etc.
> > >
> > > If I set the ignition timing to stock settings
> (6-8 degrees) the engine
> > > will ping (my knock sensor is obviously not
> functioning). I will then
> >retard
> > > the timing to around 4-6 degrees and everything
> seems fine... just the
> >fact
> > > that I'm losing some performance. :(
> > >
> > > So, I checked my spark plugs to see that I was
> running the stock 3
> >electrode
> > > Bosch plugs for the 2.0 16v, which have a heat
> rating of 6.
> > > Due to my higher compression, I sourced a
> different Bosch plug with heat
> >rating
> > > of 5 (colder plug). Thinking that this would
> dissipate heat faster
> > > and help solve my pre ignition issue... nope.
> > > The new plugs don't seem to have helped.
> > >
> > > Anyone have experience in the high-compression
> world with this pinging
> > > issue. Sure I could run octance booster or race
> gas, but I know that
> > > there must be a way to run 93 pump gas... right?
> :/
> > >
> > > If I go to a colder plug (like a 4 rating),
> would this possibly help?
> > >
> > > TIA!
> > >
> > >
> > > =====
> > > Benjamin Harder
> > > 86 Scirocco 16v
> > > 80 Scirocco 16v
> > > 93 Passat GLX
> > >
> > > http://www.geocities.com/vwtype53/
> > >
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