1227165 Tuning Advice

[Bruce Wilcox (EUS)]

Hi Mark,

Could you elaborate a little more on why the base timing change would work??
The part throttle operation is great. No knock counts anywhere in the
operation envelope. The problem seems to occur at WOT high LV8 loads (>=
240) and RPM's >= 3000. Bruce Plecan thinks that WOT total advance in the
28° - 32° range is reasonable. From the Diacom data + 4° extra base timing
advance, the total advance calculates to 22°.  This number seems very
reasonable. However, I will try your suggestion.

What is the difference between the "load" parameter and "LV8"??  I see
references to both.

Thanks and Best Regards,

Bruce

> -----Original Message-----
> From:	Mark Romans [SMTP:romans at pacbell.net]
> Sent:	Friday, April 23, 1999 12:57 AM
> To:	gmecm at efi332.eng.ohio-state.edu
> Subject:	Re: 1227165 Tuning Advice
> 
> Try putting the initial advance back to stock and recheck it without
> changing anything else.
> Mark
> -----Original Message-----
> From: Bruce Wilcox (EUS) <EUSBEW at am1.ericsson.se>
> To: 'gmecm at efi332.eng.ohio-state.edu' <gmecm at efi332.eng.ohio-state.edu>
> Date: Thursday, April 22, 1999 11:43 AM
> Subject: RE: 1227165 Tuning Advice
> 
> 
> >Thanks Dave,
> >
> >I looked at the diacom+ WOT data.
> >
> >2000 <= RPM <= 5500
> >
> >1st Gear: minimum retard = 5.8° , maximum retard = 9.7°
> >2nd Gear: minimum retard = 4.8° , maximum retard = 10.2°
> >3rd Gear: minimum retard = 7.2° , maximum retard = 12.5°
> >
> >I think the EPROM tables should be modified. What is your opinion??
> >
> >Thanks and Best Regards,
> >
> >Bruce
> >
> >
> >
> >> -----Original Message-----
> >> From: David A. Cooley [SMTP:n5xmt at bellsouth.net]
> >> Sent: Thursday, April 22, 1999 7:49 AM
> >> To: gmecm at efi332.eng.ohio-state.edu
> >> Subject: Re: 1227165 Tuning Advice
> >>
> >> At 01:36 PM 4/22/99 +0200, you wrote:
> >> >Hi,
> >> >
> >> >Presently, I am trying to optimize the ECM tuning. The application is
> a
> >> MAF
> >> >87 TPI Camaro with a moderately modified 355 CI (aluminum heads)
> motor.
> >> >
> >> >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??
> >> >
> >>
> >> Is this at idle or in all blm cells?
> >> If it's all, then dropping the FP to 37-38 psi Idle may be a good
> place...
> >> 110 is low, but not out of range for the ECM.
> >>
> >> >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.
> >>
> >> A "tickle" to the knock sensor with no audible knock means you are
> running
> >> the max for your fuel/engine combo...  What you really need to look at
> is
> >> knock retard degrees and see what it says.  Knock counts on my 95
> lesabre
> >> start at 0 when the key is turned on, but the engaging of the starter
> to
> >> the ring gear causes 10-15 knock counts as you crank...  If Knock
> retard
> >> is
> >> less than 2 degrees at WOT, your timing is just fine.
> >> ===========================================================
> >>            David Cooley N5XMT           Internet: N5XMT at bellsouth.net
> >>      Packet: N5XMT at KQ4LO.#INT.NC.USA.NA   T.A.P.R. Member #7068
> >>    Sponges grow in the ocean... Wonder how deep it would be if they
> >> didn't?!
> >> ===========================================================
> >