1227165 Tuning Advice

[Bruce Wilcox (EUS)]

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??

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. 

Please note: the baseline knock-counts are from the initial start routine.

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)