1227165 Tuning Advice

[Bruce Wilcox (EUS)]

Thanks for the reply Bruce.

1. The heads are Air Flow Research 190's. The overall Compression Ratio is
10:1.

2. This data represents the first performance baseline.

3. The injector pulse widths are listed below.

    1st Gear: 8.5 - 9.6 mS
    2nd Gear: 7.8 - 10.0 mS
    3rd Gear: 8.5 - 11.0 mS

4. What methods can be used to analyze the starting mode knock counts???

5. The engine is so loud I can not hear the WOT pre-ignition or spark knock.
Can the knock sensor get false triggers??? What compression ratio generates
enough noise to create false triggers???

Thanks and Best Regards,

Bruce 

> -----Original Message-----
> From:	Bruce Plecan [SMTP:nacelp at bright.net]
> Sent:	Thursday, April 22, 1999 11:08 AM
> To:	gmecm at efi332.eng.ohio-state.edu
> Subject:	Re: 1227165 Tuning Advice
> 
> 
> ----- Original Message -----
> From: Bruce Wilcox (EUS) <EUSBEW at am1.ericsson.se>
> To: <gmecm at efi332.eng.ohio-state.edu>
> Sent: Thursday, April 22, 1999 7:36 AM
> Subject: 1227165 Tuning Advice
> 
> 
> > The application is a MAF
> > 87 TPI Camaro with a moderately modified 355 CI (aluminum heads) motor.
> 
> GM heads?.
> 
> > There are two minor problems.
> > 1.
> > The nominal BLM is consistently below 128. Depending on the exact BLM
> cell,
> > the nominal value approaches 110. The integrator hovers around 128 +/-
> 5.
> > Since the BLM is low and the integrator is OK, my guess is the fuel
> pressure
> > is high (44 PSI @ idle, 50+ PSI @ WOT). Is this a reasonable diagnoses??
> 
> Have you run any performance base lines?..  Fuel Pressure makes a ton of
> difference at WOT..  Find out where your at with WOT AND cruise, then
> judge
> where you need to move things.  (Also, measure PW/Duty cycle).
> 
> > 2.
> > The knock sensor triggers during extended WOT test runs (hard to hear
> any
> > audible effects). Given a WOT test run through the first three gears
> (RPM
> > range: 2000 - 5500 RPM), the knock counts go up roughly 13 - 15 counts.
> Part
> > throttle "closed loop" conditions perform great (no knock & excellent
> > performance). I would like to eliminate the root cause of the additional
> > knock counts. Since the "closed loop" part throttle performance is
> > excellent, I do not want to back off the base timing ( 10° BTDC). My
> guess
> > is the spark table needs modification. Any comments or suggestions are
> > appreciated.
> 
> Again, you need some baseline info so you know what you've got, so you
> know
> where to go.  At this stage you don't know it it's too much timing, or too
> lean.
> You need to be able to make a change, and guage the results...
> >
> > Please note: the baseline knock-counts are from the initial start
> routine.
> 
> Your generating knock counts while cranking?.
> Bruce
> >
> > Thanks,
> >
> > Bruce E. Wilcox
> > Sr. Staff Engineer
> > Ericsson Inc.
> >
> > Bruce.Wilcox at ericsson.com
> > wilcox at rtp.ericsson.se
> >
> > 919-472-7054 (phone)
> > 919-472-1103 (fax)
> >