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Main spark vs. Load

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Old Nov 15, 2004 | 07:51 PM
  #1  
adambros's Avatar
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From: Fairfield, Ca
Car: 1991 Firebird
Engine: 355 TBI
Transmission: WC-T5
Main spark vs. Load

This past weekend I took the car back to the dyno. Second time on the dyno. First time back with BBC injectors, and increased fp.

The tech said after two pulls that it looked like I was running too much timing at WOT. I made sure I was not adding any timing in PE. It wasn't -- zeroed out.
Then looked at the Main Spark vs RPM vs Load table. Sure enough the 2800, 3200, 3600 rows, MAP (Kpa) colums 30-55 the value was set to 40.1. He said that was too much and recommended I drop the values to ~32, that it would also lean me out a bit. I did -- and made signifigant gains above 4K.

Going back to it now, trying to make progress and understand why the changes produced the effect . . .

why did making changes from 30-55 Kpa make any difference ?
Isn't 90-100 Kpa WOT ? Thats what ALDL reports MAP sensor is in the logs. Why did the change down low help up high ?

now were getting somewhere, 243/316 at the wheels
-- but still a long road ahead.
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Old Nov 16, 2004 | 07:12 AM
  #2  
RBob's Avatar
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From: Chasing Electrons
Car: check
Engine: check
Transmission: check
You are correct in that 100 KPa is WOT. The changes at the low end (35 KPa) would not have made a difference. If there really was a difference then two possibilities come to mind: did you change anything else along with the low KPA SA, and, is the ECU, TDF, or whatever definition file you are using correct?

RBob.
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