PorKen

I updated the PK MAF patch to the final rate code which I am using.
As you can see, below, it works great! (It's now as consistent as my S3... )


I added another patch which I think might be good in the long run.
It fully opens the IAC/ICV when the idle switch is on and RPMs are over 4000. (Decel = no fuel.)
This ought to cut down on oil being drawn into the intake/cylinders when the throttle plate is closed suddenly at very high rpms.
Note the green MAF trace after the 'run'. (The LH2.3 IAC can rev engine to >2500 RPM, unloaded/warm!)



I am still going through and adding ignition advance and fuel, but WOT is pretty close to being 'done'.

PorKen

You might have thought - why not open the IAC/ICV at WOT to get more air in?

It appears, conversely, to restrict airflow (green = MAF) and make it slower (black = RPM).

Turbulence and/or reducing air velocity through the throttle body?


Second gear log uphill, dashed = IAC open.

danglerb

Can you set the IAC to cycle once maybe during the rpm range so we could see transition in the same run?

I can believe from placement of the ports that it could just cause turbulence with no gains.

PorKen

I could (cuz I gots mad 8051 skilz now, playa ), but I can't justify the effort.

However, I revised the pic above to show all three 'runs' from that short logging trip. (Hit F5 or refresh page.)
(Old pic was 3/2. 2 is with the IAC open. 1 and 3 IAC coded for disabled/closed with WOT switch. 5~10 mins between each run.)

1/2 is even more dramatic.

Note as the intake and/or MAF heats up, the MAF voltage goes down, especially at the top end, as with 1/3.

FredR

Ken,

Does this imply that as the system heat soaks you get a false air reading or is the heating effect really having such an impact on mass air flow?

Apologies if I am being a bit dumb here.

Regards

Fred

Avar928

Ken,

I noticed on the Liftbars page for the S3000 chips you listed that the '88 S4 FPR can be used with a hose adapter. What adapter is this? I'm guessing there only difference between the 87-88 FPRs is just fitment to the S3?

PorKen

Not so much false as different?

MAF voltage drops or 'leans' out, from log to log, even in cold air, with stable coolant temps.
The first drop will be the most noticeable, then the voltage change gets smaller and smaller.
I have always assumed it is the temperature of the MAF electronics which affects it.

If I pop off the freeway on to my 'logging road' and right away make a run, it will be much richer than 'normal'.


The temperature of the intake system and the air inside it will affect the harmonic pulses, speed of sound in air and all that.

DKWalser

Which raises the question of how sensitive your chips are to the climate. Having been perfected in the Portland area, will they tend to run extra rich (or lean) in San Diego or Phoenix? How does elevation enter the mix? Portland's close to sea level. The air's thinner in Denver.

jpitman2

Density of air at 15C(59F) is 1.225 k/m3, at 35C(95f) its 1.1455, nearly 7% down. I would expect to see a change in fuelling for that movement....
I have seen inlet air temp on my Suby turbo go from 22C (ambient=20C) at a steady cruise to 80C after a while in stop start traffic. Hence the importance of getting external fresh air into the engine.
jp 83 Euro S AT 55k

PorKen

Some of that is handled by O2 adaptation, which also affects WOT mixture, but I spent a lot of time on making my own compensation.


At WOT, the MAF freq value is combined with RPM and averaged with the MAF ideal + base table + the WOT table.


I made a new MAF ideal table for WOT, over which the LH overlays a new 64 column WOT table.

The MAF ideal is sloped at a constant rate with higher numbers associated with lower MAF values (the companion base table is flat).

The theory is, I tune at my weather (air pressure, temp, dew point) and the sloped table compensates for a lower or higher MAF value at the same RPM.


In practice, it works great for gear to gear (which changes the MAF/RPM relationship), and does an OK job with weather.

For example, if the air is hotter, the MAF value would be lower at a particular RPM.
This would normally lean out the AFR, but the sloped ideal table compensates by returning a higher value.


Overall, my aim is to keep AFRs somewhere in the 12's.


Note when both the logged terrain and the AFR are flat, injector duty will match a HP graph fairly well.

AFR, MAF volts, Inj duty, RPM


With the new MAF smoothing code the WOT table now very closely matches injector duty.
It is read and laid diagonally across the MAF ideal table as MAF units and RPMs rise.


New MAF ideal for WOT.

PorKen

Updated MAF rate code.
Functionally the same; more elegantly coded. (Cue nerdly laughter. )


Added 'GTS mod' patch, no limit Adaptation level.
Stock limit, pre-GTS, 5Eh = 0.37ms = 20%?


Added O2 loop bypass MAF and RPM thresholds.

MAF value is a guesstimate. Stock is 252? (3.6 x 46h, should be log function)

RPM values are in hex, sample values below.

4000 3C
3925 3D
3850 3E
3775 3F
3700 40
3600 41
3500 42*
3400 43
3300 44
3240 45
3175 46
3110 47
3050 48
2990 49
2925 4A
2860 4B
2800 4C
2750 4D
2700 4E
2650 4F
2600 50


Note again that values must be entered in two places.


Removed IAC open patch - don't think anyone would use that anyway.

davek9

wrong thread but, the S3 connection to Stock FPR has a nipple for a Clamp fitting, the Early '87 is the same (direct replacement).

The later '87 - '88 FPR has a threaded (input) fitting and will required a "threaded to nipple" fitting, these can be found or sourced from old FPR's.

Edit: nice going Ken, I sure do like the one's you made for the S3

Dave

Hilton

Thank you!

I just updated a new "blank" (unchanged) ST2 BIN with the patch to apply MAF smoothing at all rpm's.

I'll have a play with it next weekend - I'm currently (slowly) experimenting with measuring injector opening time on my '87, and will be putting my 4-hole injectors back in hopefully this weekend in between kids stuff and beach patrol.

PorKen

This doesn't have to do with the MAF per se, but it does have to do with smoothing.

Along with MAF smoothing, I have now applied averaging to system voltage and averaging plus reduced-sample-rate to coolant temp on both the EZ and LH with good effect.
Both inputs are subject to spikes hi/lo which directly affect ignition and injection. (Neither have any smoothing in the stock code.)
All modes of running are improved. Idles like butta. (Sorry, this code is too dense for a patch.)


System voltage is used for timing just about everything, injector time, ignition dwell, idle control, as the voltage level controls how fast devices respond.

Coolant temp is used more for reading from compensation maps. Coolant temps at the Temp2 sensor in the head crossover vary wildly and the sensor reacts quickly, leading the EZ/LH to jump from column to column, creating unpredictable AFR bumps which really confound tuning.
The unpredictability goes up with the amount of coolant flow = RPM, so lower gears are often a real mess.

Because of the random nature of the coolant input, it was not feasible previously to use the warmup maps for controlling AFR at running warm<->hot temps.
With smoothing enabled, WOT AFR can be controlled in a predictable way, instead of having to make it default (very) rich to cover all conditions.


These all kind of look the same now...but the amplitude of the AFR graph (purple) IS getting smaller and smaller. (The dropout is a misfire.)



This code is going into my S4 chips, but I hope to apply it to the S3 chips at a later date.

PorKen

What I would have given a year ago for that line from 5700-6300 (peak HP)! (Compare with the first page of this thread, #1 or #12(!).)

This isn't the best looking log, but it does show something I've forgotten about. (Thankfully, I haven't needed to do logging runs for a few months.) The rich 'drops' are misfires. I should check the gap on the spark plugs, but they also appear when the engine temperature has not stabilized I've found. For the intake harmonics to do their thing, temps have to be in the proper range, not too cold, not too hot - speed of sound in air, 'n such. This was a warm first WOT pass. Where there is harmonic 'overpressure' it usually requires a lot more fuel, but if the intake harmonics aren't working, it will look too rich, or there could be misfires as shown.

Knocks can also show up at unexpected rpms on the first pass, too, for the same reasons.