Individual Cylinder AF Adjust

socrace at ameritech.net socrace at ameritech.net
Thu Feb 7 20:20:59 GMT 2002


Probably, the method below is mainly useful to identify a cylinder if you 
only have a single channel scope to look at your sensor with (or you blew 
one of your probes when you tried to sync off the #1 spark plug wire!). Or 
use it as a reality check.
Bob D

At 12:16 AM 2/6/2002 -0600, bcroe at juno.com wrote:
>OK, So what's next?  Calibrate a scope to read A/F?  Set up
>a sampling system to read 8 cylinders based on 8 time
>delays you set?  Or is it 8 cam positions?  Is the delay constant
>relative to throttle, rpm, cam postition, and/or time?  How do
>we get to actual numbers?  Bruce Roe
>
>On Tue, 05 Feb 2002 22:03:04 +0100 Lasse Langwadt Christensen
><langwadt at ieee.org> writes:
> >
> >
> > socrace at ameritech.net wrote:
> > >
> > > At 09:29 PM 1/29/2002 +0100, Jorgen_Karlsson wrote:
> > >  >Cylinder selective measurement is hard to implement
> > > > because of other reasons, you will have to know the
> > > > time it takes for the exhaust gas to reach the sensor
> > > > and that is not a trivial task to find out.
> > >
> > >     There's a couple of work-arounds for the "gas transport time"
> > > problem you mentioned.
> > >     One way is to mount 2 sensors in split manifolds (one in each
> > > manifold). This works well with sbc stock manifolds, for example.
> > > The passenger side manifold 8,4 pair fire 90 deg apart
> > > versus the 6,2 pair which are 270 deg apart, the other
> > > wo pairs are both 180 deg apart. So, the 2 pulses the
> > > sensor sees that are closest together are cylinders 8 for
> > > the leading and 4 for the trailing. The pairs surrounding this
> > > one, 2,8 and 4,6 are both 180 deg, or twice the pulse width
> > > of the 8,4 pair, making it fairly easy to spot. With the right
> > > algo, you can watch this using a narrow band sensor.
> > >    Actually using this to control individual cylinders is still no
> > > picnic, of course!
> > > Bob D
>
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