Dyno-Less tuning?

[peter paul fenske]

Awesome Thor
At 01:49 AM 5/19/98 -0400, you wrote:
>
>Brief recap... this is a 68hc11 EFI (fuel only) for a Honda
>CBR600 motor.  All homemade stuff.
>Calculates base PW based on MAP, all other sensors totally
>ignored (incl RPM)... batch fired at #1 intake stroke.  How
>important is RPM (considering I'm injecting 1/rev anyway)?
>
>Ok... now that I've gotten my ECM to ignore noise on the Cam
>sensor line, I *think* I'm ready to start tuning the thing.... I
>am not having as much success as I thought I would though, so I
>have a few questions:
Prob not. Enough to get it running though
>  1. Can I effectively tune in neutral?  My data comes outta a
>serial
>      port & my host pc is AC-only. (Is there a way to hook a
>cellphone to
>      an external 9600 baud serial port/modem?  My ECM don't do
>PCMCIA!
>      I can choose from PowerTel PCS or bellsouth mobility D/A
>phones.)
>
>     I am trying to tune in neutral...  It doesn't seem to
>reflect
>     "loaded" conditions very well.  I'm currently ramping
>*slowly* to
>     try to get the "static response" tuned up.
O2 tuning is usually done with a oscillating control
loop treating the O2 input as a step. There is also
quite a delay time..
Do as GM did and tune your system for stoich with the O2 
not running. Only when you get it tuned play with the O2

>  2. What should be my goal?  Should I attempt to maintain a
>consistent
>      O2 sensor voltage across the RPM range?
>
>     I'm trying to keep the incr in throttle from making the oxy
>go lean
>     and the engine sputter & die (this is accompanied by a
>steady rev of
>     the engine at the constant throttle posn).
Transient in the simple is just delta throttle say measured at
each 6.25 mS RTI and coolant temp based on a 2 dimensional
table. This looks up a small addition to your PW
Oems use more. absolute Map, Tps, then the delta terms along with
coolant.

>  3. How do I handle transient effects?  I am toying with the
>idea of an
>     "electronic accelerator pump" that has "addtl fuel" vs.
>"delta throttle".
>     Should I make the length of the effect (decay curve?)
>adjustable or will
>     a "single shot of gas" do it?
>
>     Right now my maps look like a small slope in the 0-10PSIA,
>and about 10x
>     that in the 10PSIA+ entries.  This gives ok starting from
>idle, but
>     flooring it while 6-8K will still cause it to stumble
>(badly!).
>
>  4. Do Ego's have memories?  At times, the RPM will increase
>before the throttle
>     opens, the oxy goes lean & the engine quits.  The only thing
>I can think of is
>     that the mixture was already lean (but the sensor was still
>reading rich), so
>     the R's went up.  The oxy falls .2-.6 secs after the rpm
>starts its "death rev."
>     These are 1yr old sensors, 3" from exhaust port, running
>M85.  They have been
>     sooted to death before (as have the plugs....). [PSST. CSH
>trick:  To clean the
>      plugs, we lean the A/F mix by switching off the fuel pump
>before shutdown!]
>
>  5. I am getting some wild variations at certain R's among the 4
>Ego's.  It only happens
>     at certain R's (& best sound is a Rich-Lean-Lean-Rich
>pattern [1234])... does this
>     indicate an airflow problem in the intake system (composed
>of PVC, 18mm restrictor)?
>     How bad does this hurt us/the engine?
I hope you are filtering you map. A simple first order digital
filter is easy to implement. Do it at each 2nd RTI or so

also pull vac from a combined fitting to get more consistent
map.
>  6. I'm taking MAP readings about 6" from the cylinder inlet.
>The intake is 1" sch40 PVC
>     molded in an attempt to maintain an 8 degrees exit angle to
>the head from the 18mm
>     restrictor (a la fluids).  Is this a bad place to do this?
>I tried at the test ports
>     of the cyl intake, but the vacuum fluctuated wildly
>there....
>
>---
>
>I have some nice long data logs that look like (like hondo?):
>  CamDT, Throt, PSI, Tp1, Tp2, Tp3, Tp4, Ox1, Ox2, Ox3, Ox4
>
>I've loaded these into excel to assist me... does anyone have a
>"tuning your ecm with excel" faq?
>I have lots of points, but I have no idea whats going on....
>they make pretty lines...
>
>Currently, I'm leaning the whole map out until the engine hardly
>runs, finding that MAP value, twiddling with it (slowly) until I
>get Ego's in the range I want (which changes the RPM!), doing the
>same to the new RPM... I can't quite get it to converge.  To get
>the upper PSI points, I have just *completely made up numbers*
>that attempt to elimanate idle->WOT stumble.
>It doesn't help 1/2throt->WOT very much.
>
>I'm also thinking about making the ECM output binary... I can't
>get anywhere near 1 row/CamR with this excel/ascii format (9600
>baud), but I'm wondering how much that extra data would help me,
>vs the trade-off in convenience/readability....
>
>As you can see, I'm confused when we try to get these things to
>work in reality instead of theory...
>
>TIA,
>Thor Johnson

Pretty good so far..

:peter