This is just something I thought you guys may want to keep in mind or look out for. Not everyone will have to worry about this, and the qualifications for entering PE mode are different for different systems, years, and models.
This is a small section of some of the PE qualifier calibrations in the ANHT hack - a code that runs in early 1990's GM products.
Later PCMs (OBD2) normally have more qualifiers, and higher thresholds in order to go into PE mode. In other words they maintain stoich for a wider range of operation.
Quote:
**************************************************
* PWR ENRICH PARAMS
* ANHT TYPE $8D
**************************************************
L85FF: FCB 230 ; 8.1 Kpa VAC to ENABLE PWR ENR
; ARG = 256 - (Kpa * (256/80))
L8600: FCB 10 ; 3.1 Kpa, VAC HYST FOR PWR ENRICH Kpa
; ARG = Kpa * (256/80)
L8601: FCB 16 ; 6.25% TPS HYST, PE off if TPS LT (L8603 - L8601)
L8602: FCB 209 ; USE TBL L8608 IF COOL = or GT (116c), (244F)
;--------------------------------------------------
; PWR ENRICH TPS THRESHOLD vs RPM
; FOR NORMAL COOLANT
; *** WOT ***
;
; TBL = TPS% * 2.56
;--------------------------------------------------
; TPS% RPM
;------------------------------
L8603: FCB 128 ; 50 400
FCB 128 ; 50 1200
FCB 128 ; 50 2000
FCB 154 ; 60 3200
FCB 180 ; 70 4800
;--------------------------------------------------
;--------------------------------------------------
; PWR ENRICH TPS THRESHOLD vs RPM
; FOR HIGH COOLANT
; *** WOT ***
;
; TBL = TPS% * 2.56
;--------------------------------------------------
; %TPS RPM
;------------------------------
L8608: FCB 128 ; 50.0 400
FCB 128 ; 50.0 1200
FCB 38 ; 14.8 2000
FCB 38 ; 14.8 3200
FCB 38 ; 14.8 3800
;--------------------------------------------------
************************************************** ***********
* WOT AFR = 6553.6/((TBL L8608 + TBL L860D + 128) * 445)/256)
* or
* WOT LAMBDA = (LAMBDA C + LAMBDA W)
* or
* WOT AFR = 14.7/(LAMBDA C + LAMBDA W)
************************************************** ************
;--------------------------------------------------
; PWR ENRICH F/A %CHG vs COOLANT
; *** WOT ***
;
; ANHT, TYPE $8D
;
; TBL = (LAMBDA * 256) + 128
;--------------------------------------------------
L860D: FCB 8 ; TABLE LENGTH +1
;
; LAMBDA C DEG c
;------------------------------
FCB 140 ; 0.546 -40
FCB 125 ; 0.488 -16
FCB 112 ; 0.438 8
FCB 86 ; 0.336 32
FCB 58 ; 0.227 56
FCB 58 ; 0.227 80
FCB 58 ; 0.227 104
FCB 58 ; 0.227 128
FCB 58 ; 0.227 152
;--------------------------------------------------
;--------------------------------------------------
; POWER ENRICH FUEL/AIR % CHG vs RPM
; *** WOT ***
;
; ANHT, TYPE $8D
;
;
; TBL = LAMBDA+128/256
; TBL = (% CHG * 1.28) + 128
;--------------------------------------------------
; LAMBDA W RPM
; ---------------------------------
L8617: FCB 113 ; 0.941 0
FCB 113 ; 0.941 400
FCB 113 ; 0.941 800
FCB 113 ; 0.941 1200
FCB 115 ; 0.949 1600
FCB 115 ; 0.949 2000
FCB 115 ; 0.949 2400
FCB 137 ; 1.035 2800
FCB 128 ; 1.000 3200
FCB 160 ; 1.125 3600
FCB 150 ; 1.086 4000
FCB 157 ; 1.113 4400
FCB 138 ; 1.039 4800
FCB 138 ; 1.039 5200
FCB 138 ; 1.039 5600
FCB 138 ; 1.039 6000
FCB 138 ; 1.039 6400
;--------------------------------------------------
|
What you're seeing with the TPS thresholds is 50% - 70% TPS to qualify for PE mode. This doesn't mean that hitting that TPS% always triggers PE mode. The other qualifiers also have to be met, but it will happen most of the time when the TPS qualifier is met.
If you have no way to recalibrate your ECM, then there is the option of using a tricker circuit for the TPS to keep it either locked at a low position or something that will limit the voltage to a max value.
_________________________
There is also AE - Acceleration Enrichment to cover throttle modulations.
Depending on all the qualifiers, quite a large amount of extra fuel can be injected in momentarily when the throttle position is increased, or the MAP value increases suddenly.
Here is a sample of what some of those qualifiers look like:
Quote:
****************************************
* DIFF TPS ACCEL ENRICH TABLES & PARAMS
* ANHT 5.7l V8, $8D ECM
****************************************
L852E: FCB 3 ; 13.5% TPS MIN FOR ACCEL ENRICH PROP TO BASE PW
L852F: FCB 1 ; 1 INJ IN FUEL LIMITING
L8530: FCB 12 ; ACCEL ENR LASTS 12 REF PULSES
L8531: FCB 128 ; 50% TPD DIFF FOR V6 ACELL ENR CALC
;
L8532: FDB 454 ; 6.92 MSEC MAX ACELL ENR PW LIMIT
;
L8534: FCB 32 ; 0.125 MULT FOR 12.5 Msec TPS Acell Enr
L8535: FCB 32 ; 0.125 MULT FOR DIFF TPS * 32
;
L8536: FCB 1 ; USE 4-7 OF TBL L8563 FOR 1 REF PULSE FROM AE or DE
L8537: FCB 3 ;
.
.
.
.
*****************************************
* DIFF MAP ACCEL ENRICH TABLES & PARAM'S
* ANHT, TYPE 8D ECM
*****************************************
L857C: FCB 6 ; 0.023, FILTER COEF, ACELL ENRICH FILT MAP TERM
L857D: FCB 10 ; FILTER COEF, ACELL ENRICH FILT RPM TERM
;
L857E: FCB 3 ; 75 RPM, NEG DECELL RPM THRESH FOR USING L857F
L857F: FCB 128 ; 50%, L859A THRESH MULT ON DECEL RPM
;--------------------------------------------------
; MAP ACEL ENRICH FACTOR vs DIFF MAP
;
; DIFF MAP ABOVE MIN
;--------------------------------------------------
; MULT KPA diff
;----------------------------------
L8580: FCB 24 ; 9.375 0
FCB 32 ; 10
FCB 36 ; 20
FCB 40 ; 30
FCB 51 ; 40
FCB 64 ; 25.000 50
;-------------------------------------------------
;------------------------------------------------------
; MAP Acell Enrich COOLANT MULT
;
; VAL = MULT
;------------------------------------------------------
L8586: FCB 8 ; 9 LINE TBL
;
; Deg c
;--------------------------------------
FCB 55 ; -40
FCB 55 ; -16
FCB 55 ; 8
FCB 55 ; 32
FCB 32 ; 56
FCB 26 ; 80
FCB 19 ; 104
FCB 19 ; 128
FCB 19 ; 152
.
.
.
.
;------------------------------------------------------
; Acell Enrich COOLANT MULT vs COOLANT
;
; VAL = MULT * 128
;------------------------------------------------------
FCB 8 ; 9 LINE TBL
;
; MULT Deg c
;--------------------------------------
FCB 55 ; 0.429 -40
FCB 55 ; 0.429 -16
FCB 55 ; 0.429 8
FCB 55 ; 0.429 32
FCB 32 ; 0.250 56
FCB 26 ; 0.203 80
FCB 19 ; 0.148 104
FCB 19 ; 0.148 128
FCB 19 ; 0.148 152
;------------------------------------------------------
;------------------------------------------------------
; Acell Enrich DECAY FACTOR vs COOLANT
;
; VAL = %CHG PER INJECT * 2.56
;------------------------------------------------------
L8590: FCB 8 ; 9 LINE TBL
;-
; %CHG Deg c
;----------------------------------
FCB 102 ; 39.8 -40
FCB 102 ; 39.8 -16
FCB 102 ; 39.8 8
FCB 102 ; 39.8 32
FCB 102 ; 39.8 56
FCB 102 ; 39.8 80
FCB 128 ; 50.0 104
FCB 128 ; 50.0 128
FCB 128 ; 50.0 152
;------------------------------------------------------
;------------------------------------------------------
; DIFF MAP for Acell Enrich Enable
;
; VAL = DIFF MAP * (16/5)
;------------------------------------------------------
; Kpa %TPS
;----------------------------------
L859A: FCB 10 ; 3.13 00.0
FCB 10 ; 3.13 12.5
FCB 10 ; 3.13 25.0
FCB 10 ; 3.13 37.5
FCB 10 ; 3.13 50.0
;------------------------------------------------------
;------------------------------------------------------
; MAP Acell Ebr FACTOR MULT vs TPS LOAD
;
; VAL = FACTOR * 64
;------------------------------------------------------
; FACTOR TPS %
;----------------------------------
L859F: FCB 64 ; 1.00 00.0
FCB 64 ; 1.00 12.5
FCB 64 ; 1.00 25.0
FCB 64 ; 1.00 37.6
FCB 64 ; 1.00 50.0
;------------------------------------------------------
|
_________________________
I didn't write this next part. It's from DIY-EFI.org
Quote:
Q: What about this PE stuff?
PE refers to the additional fuel and spark which is added to the values in the existing fuel and spark tables. There are two tables for PE enable, one for normal coolant temps ($L6803 - $L6807) and one for high coolant temp ($L6808 - $L680C). The high coolant temp value, 245 deg F stock, is at $L8602.
Both tables are indexed by %TPS vs. RPM, meaning that PE is enabled if at a certain RPM "X" the %TPS exceeds a certain amount. Yes, you can set PE to come on at 1000rpm and 10% tps. Would it be a good idea? Probably not....
The table at $L8617 is the heart of PE fueling. It is indexed by RPM vs. % change in AFR. Here you are setting the target AFR at a specific RPM. The value in the table is a percentage change from 14.7:1. Higher numbers mean a richer mixture. From the anht_hac, the value in the table is ((% CHG * 1.28) + 128). For example a 6.25% change in AFR ( approx 13.7:1 AFR) would corrospond to a value of 136 in the table.
NOTE: due to the fact that standard 02 sensors are only accurate (and not very accurate at that) at 14.7:1 AFR, so if you specify a 12:1 AFR, you're going to get something CLOSE to it. A WB02 (wide-band 02) is the only way you'd really know what your actual AFR is.
PE Spark is found in a table at $L81B3. It is indexed by RPM and spark added in degrees. From the anht_hac, the amount added is ( SA * 256/90 ) where SA is in degrees.
It's important to have the basic tuning correct, with the BLM values at or near 128 prior to tuning PE. If prior to entering PE mode the BLM is above 128 the fuel correction is applied along with the PE fueling. If it is below 128, the BLM is brought up to 128 and then PE fuel applied.
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