SOHC V6 tuning

[2000StreetRod]

calculating VE

Normalized air charge, referred to as load, is a unitless parameter indicating the ratio of the cylinder air charge to the theoretical air charge of a full cylinder at EEC Standard Temperature and Pressure (standard air charge, SARCHG). Using load makes all engines more directly comparable, and allows a similar scaling for all table look-ups.

The definition of standard air charge is:

SARCHG = 2.701E-09 * pi * [(B/2)**2] * S lbm/intake stroke

where B = bore (mm), S = stroke (mm), 2.701E-09 = density of air in lbm/cubic mm

SARCHG = Advantage Engine Displacement = 0.00179 lb/m per cyl per rev for our stock tunes

load_raw = Uncorrected air charge at air meter/SARCHG

So you're using the stock 55 mm MAF sensor with an electronic scalar (voltage reducer) and then also modified the MAF transfer function (MTF). That means the measured airflow is inaccurate (less than actual) and so is the load calculation. Assuming that the stock MTF and load calculation was accurate your actual load now is the PCM calculated load divided by the electronic scalar (.90) and multiplied by the ratio of the stock MTF value to the changed MTF value for a specific voltage output.

If your stock NA max load was .80 then your actual max load with 6 psi boost should be about .80 * (14.7 + 6)/14.7 = 1.12

What type of electronic scalar are you using? I tried building an analog amplifier when I switched from my stock 55 mm MAF sensor to a 90 mm MAF sensor but couldn't achieve constant amplification over the wide temperature range in the engine compartment. Are you using a digital converter?

 

[RangerOZ]

MAF and VE

Normalized air charge, referred to as load, is a unitless parameter indicating the ratio of the cylinder air charge to the theoretical air charge of a full cylinder at EEC Standard Temperature and Pressure (standard air charge, SARCHG). Using load makes all engines more directly comparable, and allows a similar scaling for all table look-ups.

The definition of standard air charge is:

SARCHG = 2.701E-09 * pi * [(B/2)**2] * S lbm/intake stroke

where B = bore (mm), S = stroke (mm), 2.701E-09 = density of air in lbm/cubic mm

SARCHG = Advantage Engine Displacement = 0.00179 lb/m per cyl per rev for our stock tunes

load_raw = Uncorrected air charge at air meter/SARCHG

So you're using the stock 55 mm MAF sensor with an electronic scalar (voltage reducer) and then also modified the MAF transfer function (MTF). That means the measured airflow is inaccurate (less than actual) and so is the load calculation. Assuming that the stock MTF and load calculation was accurate your actual load now is the PCM calculated load divided by the electronic scalar (.90) and multiplied by the ratio of the stock MTF value to the changed MTF value for a specific voltage output.

If your stock NA max load was .80 then your actual max load with 6 psi boost should be about .80 * (14.7 + 6)/14.7 = 1.12

What type of electronic scalar are you using? I tried building an analog amplifier when I switched from my stock 55 mm MAF sensor to a 90 mm MAF sensor but couldn't achieve constant amplification over the wide temperature range in the engine compartment. Are you using a digital converter?

I really appreciate your help, your precise scientific and analytical approach.
I speculate you are a scientist or engineer by trade ?

Yes I am using a stock MAF and throttle body.

Yes my engine size is as you have recalculated it was actually showing 0.00178 and I changed it to 0.00179.

When pulleys only allowed 4 psi I was reaching 960 AD counts on the MAF
At this point I was peaking at ~77% VE
There was no MAF scaling.
The only change had been to use the injector values from SCT.

The next pulley got me towards 5.0 psi and the ad counts at 975
As the limit was 980 I modified it to max (1023) and extrapolated the curve to give me a sensible value for airflow at 1023.

In anticipation of going to 8 psi I added a simple resistor divider to give me 91% of the output voltage. Thus the MAF which can produce up to 12 volts can now generate 5.5 volts and still be seen by the AD as only 91% of 5.5 or 5.0v.

I plotted the std MAF function.
I used excel to create a 4th 5th and 6th order polynomials for that transfer function. The 5th was the best fit.

y = -1E-26x5 + 1E-19x4 + 8E-14x3 + 7E-08x2 + 0.0107x + 52.087
y is Air flow
x is ad counts

Then to establish the new air flow value for the scaled voltage I divided the value in the left of the MAF transfer by 0.91 then used that in the above polynomial to calculate the new air flow value. Then stored taht back into the table. ie more air for each ad count

I used excel to check the new MAF function still had the same characteristic polynomial.

In the working range which is above 200 ad counts the Air Flow increase was between 20 and 33 % more, higher at the higher end of the scale. The above polynomial is not linear.

 

[RangerOZ]

I agree with your description of how VE is essentially proportional to boost.
And all my boost changes have followed this relationship.

The thing is that my NA VE really really seems to be 0.6
ie (14.7 + 4)/14.7 *0.6 is approx 0.77

 

[RangerOZ]

The spark table I showed has got the part throttle now under control.
But in the boost zone it seems to be excessively low.

I can only read a voltage from the knock sensor and do not know how to translate that to a knock event.

I do not see any changes to timing when I here knock.
ie all my part throttle knock sensing has been by ear.

Maybe there is a fault with the knock (statement of the obvious) but from data logs I do not know as I have nothing to compare against.
But my ear has go me to no part throttle knock and do loss of fuel economy.

On boost but off WOT is feels strong WOT seems to be lack lustre ( and why should be good with only 10 degrees of timing)


I am suspicious - I'm missing something

 

[2000StreetRod]

77% ve?

I really appreciate your help, your precise scientific and analytical approach.
I speculate you are a scientist or engineer by trade?

I am an electrical engineer by degree and a retired aerospace systems engineer.

. . . When pulleys only allowed 4 psi I was reaching 960 AD counts on the MAF
At this point I was peaking at ~77% VE

How did you determine the VE? Did you datalog the Load PID?

. . . In anticipation of going to 8 psi I added a simple resistor divider to give me 91% of the output voltage. Thus the MAF which can produce up to 12 volts can now generate 5.5 volts and still be seen by the AD as only 91% of 5.5 or 5.0v.

I compared your Ranger MAF/PCM wiring diagram to my Explorer's and they are essentially identical. Even though the supply to the MAF sensor is 12 volts I doubt that its max output can approach 12 volts. I think there is active circuitry in the MAF sensor. However, I have read that the max output can be at least 6 volts. What resistor values did you use for the voltage divider? The PCM A/D converter may need a high impedance.

I plotted the std MAF function.
I used excel to create a 4th 5th and 6th order polynomials for that transfer function. The 5th was the best fit.

y = -1E-26x5 + 1E-19x4 + 8E-14x3 + 7E-08x2 + 0.0107x + 52.087
y is Air flow
x is ad counts

Then to establish the new air flow value for the scaled voltage I divided the value in the left of the MAF transfer by 0.91 then used that in the above polynomial to calculate the new air flow value. Then stored taht back into the table. ie more air for each ad count

I used excel to check the new MAF function still had the same characteristic polynomial.

In the working range which is above 200 ad counts the Air Flow increase was between 20 and 33 % more, higher at the higher end of the scale. The above polynomial is not linear.

Below is the Advantage III plot of the stock 55 mm MTF.

It appears to be fairly linear near the max. My stock table top entry is 1023.9/5.0044 volts.

 

[RangerOZ]

VE from data log.

The resistor divider (0-5v Signal ) 4k7 (tap point) 47k (0 volts)
There are some MAF that are limited to 6v or there about
The other generate an output all the way to the supply rail.
For me either will be suitable.

The STFT had no change pre to post the MAF voltage scaling.
So I trust the circuit - at least for where I've done a lot of driving.

If you plot that data you'll see it's true characteristics.
The 5th order was a good fit in all ranges.

I've tried to err on the safe side and so if anything my MAF table is showing about 3 to 5 % more aif flow than reality. Thus the need to trim in closed loop.

But you are hinting at that my top end issue could be associated with the scaling.


Counts #/min
1023.984375 35.8076171875
957.734375 29.2763671875
893.90625 23.8603515625
846.234375 20.328125
792.421875 16.82421875
730.21875 13.35546875
694.625 11.626953125
630.171875 8.923828125
573.078125 6.966796875
539.53125 5.9453125
514.984375 5.283203125
473.4375 4.2880859375
441.734375 3.6259765625
406.953125 2.98828125
386.90625 2.6591796875
364.1875 2.318359375
339.234375 1.9814453125
311.203125 1.6455078125
296.0625 1.4873046875
279.890625 1.318359375
262.296875 1.15625
243.46875 0.998046875
222.203125 0.8369140625
196.421875 0.6650390625
165.734375 0.4921875
151.203125 0.4208984375
123.984375 0.3046875
107.625 0.2451171875
8.90625 0
0 0

 

[2000StreetRod]

wideband AFR meter?

Have you installed a wideband AFR meter? One is needed to check WOT performance. You can't rely on the injector specifications for your particular application. Your AFR could be lean at high loads causing detonation. Record the knock sensor retard PID to see how much timing the PCM is taking out due to your knock sensor.

 

[2000StreetRod]

MTF comparison

The PCM performs a linear interpolation for MAF AD Counts vs #/min. I decided to compare your max count to my stock MTF max count.

Stock
1023.0 30.9150

Ranger
1023.984 35.808
957.734 29.276

interpolated for 1023.0:
1023.984-957.734=66.25
1023.984-1023.0=.984
35.808-29.276=6.532
(6.532/66.25)*.984=.097
35.808-.097=35.711 for 1023.0

35.711/30.915=1.156
1/1.156=.865

However, for your voltage divider:
47000/(4700+47000)=.909
.909/.865=1.05
So at AD count=1023 your MTF correction is 5% too large

The other error potential is that even if the stock MAF sensor has the capability of outputting a voltage greater than 5 or 6 volts without performing a bench flow test the transfer function is not known. Most bench flow tests are terminated at slightly above 5 volts output. Years ago I attached my stock MAF sensor to my electric leaf blower for some testing. With the blower on high speed (120 mph) the MAF sensor output voltage was 5.25 volts. I suspect the MAF sensor sensitivity decreases rapidly above 5.0 volts. The corresponding voltage output for my LMAF 90 was 3.2 volts. According to SCT's value file for the LMAF 90, 3.2 volts is equivalent to about 19 lbs/min.

 

[RangerOZ]

I have just today had the exhaust upgrade.
Short headers (pacesetter) with 2.25 out let
Thermal coated inside and out.
Press bent 2.25 engine pipes to 3 inch collector and 3 inch resonator,
This connects to a 2.5 inch straight thru muffler and resonator.

So the wide band bungs went in to day.
The wiring to follow.

If I could find a PID apart from Knock Volts or a Spark PID apart from ( what I assume is) final spark I would be on my way to knowing what was going on.
The spark always seems to be what is in the Border Knock Table.

Thus my desperate need to get on the forum. It seems my processor code and strategy are not extensively developed.

You draw up valid questions about the top end of the MAF and the Injectors.

I go back and review the data logs I have.

 

[RangerOZ]

Original MTF
The Max MAF counts was 980
So the last 2 values being the same seemed odd


"AD counts
30 pts for 5v" V "#/min
Std"

1023984 5.0000 218769
957734 4.6765 218769
893906 4.3648 179677
846234 4.1321 154267
792421 3.8693 128496
730218 3.5656 101992
694625 3.3918 88935
630171 3.0771 69218
573778 2.8017 54599
539531 2.6345 47060
514984 2.5146 41943
473437 2.3117 34414
441734 2.1569 29130
406953 1.9871 24160
386906 1.8892 21494
364187 1.7783 18876
339234 1.6564 16191
311203 1.5196 13388
296662 1.4486 11982
279890 1.3667 10644
262296 1.2808 9326
243468 1.1888 8105
222203 1.0850 6845
196421 0.9591 5498
165734 0.8093 4062
151203 0.7383 3720
123984 0.6054 2968
107625 0.5255 2490
8906 0.0435 0
0 0.0000 0

 

[RangerOZ]

Scaled MTF
Max MAF AD now 1023

AD counts volts #/min
1023984 5.000 358081
957734 4.677 292763
893906 4.365 238604
846234 4.132 203286
792421 3.869 168245
730218 3.566 133554
694625 3.392 116265
630171 3.077 89240
573778 2.802 69672
539531 2.634 59451
514984 2.515 52834
473437 2.312 42881
441734 2.157 36260
406953 1.987 29881
386906 1.889 26594
364187 1.778 23188
339234 1.656 19816
311203 1.520 16453
296662 1.449 14875
279890 1.367 13187
262296 1.281 11561
243468 1.189 9976
222203 1.085 8366
196421 0.959 6652
165734 0.809 4922
151203 0.738 4212
123984 0.605 3050
107625 0.526 2452
8906 0.043 0
0 0.000 0

 

[RangerOZ]

My current point of pulley reduction is the second step beyond 980 unscaled.
I may go back 2 pulleys (885 scaled or 975 unscaled) and see if the problems disappears I am sufficiently suspicious to think that is worth re-testing.

Is there something special about that top value in the MTF ?
Should I be staying under the second last position for the calculations to work ?

 

[2000StreetRod]

MTF top entries

My stock MTF top two entries for lbs/min were also identical.

Advantage III prohibits changing the max AD count value but not its associated lbs/min. I chose the other 29 AD count values to get the best resolution for interpolation - less points on straight segments and more points on curved segments of the LMAF 90 bench flow test results. For MTF the PCM interpolates but does not extrapolate. However, that should not be a problem as long as the read AD value is within the range of the MTF table. Unfortunately, I've found that the PCM does not interpolate for all of the calibration constant tables. In some cases the PCM just uses the table entry just below the value read by the AD converter. Interpolation takes processor time so is not performed on less critical functions.

 

[2000StreetRod]

exhaust system

Your new high flow exhaust system should increase your max rwhp but may sacrifice some low speed torque. With my Dynomax VT muffler my max rwhp increased and my low speed rwtq slightly increased. Also, you'll probably notice that your max boost will decrease (a good thing) since there is less restriction.

 

[2000StreetRod]

selecting PIDs

When I select my PIDs using the X3 and LiveLink I have the ignition on and pick from the list available via the OBD-II port. I datalog Knock Sensor Retard Limit, Spark and Spark source. These should all be available to you. In LiveLink click on Tools, then List to decode spark source (as well as fuel and torque source).

 

[RangerOZ]

Your new high flow exhaust system should increase your max rwhp but may sacrifice some low speed torque. With my Dynomax VT muffler my max rwhp increased and my low speed rwtq slightly increased. Also, you'll probably notice that your max boost will decrease (a good thing) since there is less restriction.

The new system was wonderful until a flange gasket failed.
No noise and the perception of more go.
I already had unmodified Pacesetter headers and 2 inch engine pipes.
I was most concerned with the compromise header eit to allow connection toa std exhaust and the tube was 1.875 where the O2 was mounted and sticking the wide band in would cove half the x-section.

Fixed tomorrow I hope.

 

[RangerOZ]

When I select my PIDs using the X3 and LiveLink I have the ignition on and pick from the list available via the OBD-II port. I datalog Knock Sensor Retard Limit, Spark and Spark source. These should all be available to you. In LiveLink click on Tools, then List to decode spark source (as well as fuel and torque source).

I've done your above procedure.
I'll check again.
I did only recently collect an update ( from July 2014)which brought a whole bunch of PID not previously presented but none that helped. I heard there was another due early Jan 2015 but I've not seen it

 

[RangerOZ]

My stock MTF top two entries for lbs/min were also identical.
View attachment 82502
Advantage III prohibits changing the max AD count value but not its associated lbs/min. I chose the other 29 AD count values to get the best resolution for interpolation - less points on straight segments and more points on curved segments of the LMAF 90 bench flow test results. For MTF the PCM interpolates but does not extrapolate. However, that should not be a problem as long as the read AD value is within the range of the MTF table. Unfortunately, I've found that the PCM does not interpolate for all of the calibration constant tables. In some cases the PCM just uses the table entry just below the value read by the AD converter. Interpolation takes processor time so is not performed on less critical functions.

I am suspicious that this is the case with my Spark calculations - but not proven it.

I have been receiving updates to Application and Racer nearly every other day. This is above the minimum 2 updates each start ( 1 for the SQLite and 1 for FBH0)

I am a little surprised how dynamic this is.
I not sure what I should do to manage these updates getting in the PCM.
Should I be writing old "tunes" after each of these updates. ?

 

[2000StreetRod]

X4 limitation?

I wonder if the X4 has limited capabilities for older vehicles. I suspect the X4 was released with newer vehicles targeted and support of older vehicles as a lower priority. The PCM uses the Borderline Knock table entries as a starting point. The PCM applies "corrections" for IAT, ECT and knock sensor to the interpolated Borderline Knock table value. Have you compared the Spark value to what's in the Borderline Knock table?

 

[RangerOZ]

I wonder if the X4 has limited capabilities for older vehicles. I suspect the X4 was released with newer vehicles targeted and support of older vehicles as a lower priority. The PCM uses the Borderline Knock table entries as a starting point. The PCM applies "corrections" for IAT, ECT and knock sensor to the interpolated Borderline Knock table value. Have you compared the Spark value to what's in the Borderline Knock table?

I believe the X4 is a superset of the X3, it is an interface to the ODBII port.
I think the issue is that I have an and "outcast" processor code.

I'll have to set up a way to share pictures