1227165 Tuning Advice

[Bruce Wilcox (EUS)]

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?!
> ===========================================================